JP2003037064A - Semiconductor device manufacturing method and semiconductor manufacturing apparatus - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] To provide a technique for manufacturing a TFT with less variation in electrical characteristics. SOLUTION: After removing a natural oxide film formed on a semiconductor film surface, an oxidation treatment having an organic substance removing effect is performed to form a clean oxide film, and then laser annealing is performed to prevent contamination of the semiconductor film. Reduce. By using the semiconductor film thus obtained for the active layer of the TFT, a TFT with less variation in electrical characteristics can be obtained, and the electrical characteristics can be improved. Further, by using the semiconductor manufacturing apparatus of the present invention, it is possible to minimize a decrease in productivity and throughput.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having a circuit including a thin film transistor (hereinafter referred to as TFT) and a method for manufacturing the semiconductor device. For example, the present invention relates to a configuration of an electro-optical device typified by a liquid crystal display device and an electric device in which the electro-optical device is mounted as a component. Note that in this specification, a semiconductor device refers to all devices which can function by utilizing semiconductor characteristics, and the electro-optical device and the electric appliances are also included in the category.

[0002]

2. Description of the Related Art In recent years, an amorphous semiconductor film formed on an insulating substrate such as glass is heated or laser-annealed or both heated and laser-annealed to crystallize or improve the crystallinity. Techniques for making them widely studied. A silicon film is often used as the semiconductor film.

The crystalline semiconductor film obtained by the above technique is called a crystalline semiconductor film. The crystalline semiconductor film has much higher mobility than the amorphous semiconductor film. Therefore, if a crystalline semiconductor film is used, for example, a monolithic liquid crystal electro-optical device (a pixel driving device on a single substrate, which cannot be realized by a semiconductor device manufactured using a conventional amorphous semiconductor film) is used. And a thin film transistor (T
It is possible to manufacture a semiconductor device) in which FT) is manufactured.

As described above, the crystalline semiconductor film is a semiconductor film having extremely high characteristics as compared with the amorphous semiconductor film. This is the reason why the above research is conducted. For example, in order to crystallize the amorphous semiconductor film by heating, a heating temperature of 600 ° C. or higher and a heating time of 10 hours or longer, preferably 20 hours or longer were required. A substrate that can withstand this crystallization condition is, for example, a quartz substrate. However, the quartz substrate is expensive and it is very difficult to process it in a large area. Increasing the area of the substrate is an indispensable element especially for improving mass production efficiency. In recent years, there has been a remarkable movement to increase the area of substrates in order to improve mass production efficiency.

It is difficult to process a quartz substrate on such a large-area substrate by the current technology, and even if it is possible, it is not yet a price that can be established as an industry. For example, glass is a material that can be used to easily manufacture a large-area substrate. There is a glass substrate called Corning 7059, for example. Corning 7059 is very inexpensive and can easily be made large. However, Corning 7059 has a strain point temperature of 593 ° C., and there was a problem in heating above 600 ° C.

One of the glass substrates is Corning 1737, which has a relatively high strain point temperature. The strain point temperature of this is as high as 667 ° C. An amorphous semiconductor film is formed on this,
When placed in an atmosphere of 600 ° C. for 20 hours, there was no deformation of the substrate that would affect the manufacturing process. However, 20
The heating time is too long for the mass production process, and the heating temperature is 6
From the viewpoint of cost, it was preferable that 00 ° C be as low as possible.

In order to solve such a problem, a new crystallization method has been devised. Details of the method are described in JP-A-7-
183540. Here, the method will be briefly described. First, a trace amount of an element such as nickel, palladium, or lead is introduced into the amorphous semiconductor film.
As the introduction method, plasma treatment, vapor deposition, ion implantation, sputtering method, solution coating or the like may be used. After the introduction,
For example, when the amorphous semiconductor film is placed in a nitrogen atmosphere at 550 ° C. for 4 hours, a crystalline semiconductor film having excellent characteristics can be obtained. The optimum heating temperature, heating time, and the like for crystallization depend on the amount of the element introduced and the state of the amorphous semiconductor film.

An example of a method of crystallizing an amorphous semiconductor film by heating has been described above. On the other hand, crystallization by laser annealing can give high energy only to the amorphous semiconductor film without raising the temperature of the substrate so much. Therefore, it can be applied not only to a glass substrate having a low strain point but also to a plastic substrate or the like. Can be used.

Examples of the type of laser used for laser annealing include XeCl excimer laser and KrF excimer laser. An excimer laser pulsed laser beam with a large output is processed by an optical system so that a square spot of several cm square or a linear shape with a length of 10 cm or more is processed on the irradiated surface, and the laser beam is scanned (or A method of performing laser annealing by moving the irradiation position of the laser beam relative to the surface to be irradiated) is industrially excellent in mass productivity, and is therefore preferably used.

In particular, when a beam having a linear laser beam shape on the irradiation surface (hereinafter referred to as a linear beam) is used, a spot-shaped laser beam which requires front, rear, left and right scanning is used. In contrast, since the laser beam can be irradiated onto the entire surface to be irradiated by scanning only in the direction perpendicular to the line direction of the linear beam, mass productivity is high. Scanning in the direction perpendicular to the line direction is because it is the most efficient scanning direction. Due to this high mass productivity, it is becoming mainstream to use a linear beam obtained by processing a pulse oscillation excimer laser with an appropriate optical system for laser annealing.

Further, in order to obtain a semiconductor film having higher electric characteristics, for example, there is a method in which an amorphous semiconductor film is crystallized by heating and then laser annealing is further performed. When this method is used, the characteristics of the semiconductor film can be improved as compared with the case where crystallization is performed by either heating or laser annealing.

As a pretreatment for laser annealing, a natural oxide film is often removed for the purpose of preventing surface roughness. The composition and the thickness of the natural oxide film are not controlled, and may cause contamination or variation. In particular, when laser annealing is performed after introducing a metal element into the amorphous semiconductor film and performing heat treatment as described above, natural oxide film removal as a pretreatment of laser annealing is performed with a high concentration of the introduced metal element. It also has an effect of removing a portion, and is important for obtaining a highly stable semiconductor film with little variation in characteristics. Details of the method are described in JP-A-8-339960.

It is also known that when a semiconductor film is subjected to laser annealing to be crystallized, a convex portion called a ridge (hereinafter referred to as a ridge) is formed on the film surface. When the semiconductor film is irradiated with laser light, the semiconductor film is instantaneously melted and locally expands, and a ridge is formed on the surface of the crystalline semiconductor film to relieve internal stress caused by this expansion. The height difference of this ridge is about 0.5 to 2 times the film thickness.

In the insulated gate type semiconductor device, a potential barrier and a trap level due to dangling bonds and lattice distortion are formed on the ridge on the surface of the crystalline semiconductor film, so that the active layer (channel forming region) is formed. , The semiconductor layer including the source region and the drain region) and the gate insulating film are increased in interface level. In addition, since the top of the ridge is steep, the electric field is likely to be concentrated and becomes a source of leak current, which eventually causes dielectric breakdown and causes a short circuit. In addition, the ridge on the surface of the crystalline semiconductor film impairs the coating property of the gate insulating film formed by the sputtering method or the CVD method, and deteriorates reliability due to insulation failure or the like. Further, the surface scattering effect is one of the factors that determine the field effect mobility of the TFT, and the flatness of the interface between the active layer of the TFT and the gate insulating film affects the field effect mobility, and the interface is flat. Higher field effect mobility can be obtained without being affected by scattering.

From the above, it can be said that a low ridge is desirable. By performing the laser annealing in the inert gas atmosphere, the ridge is reduced as compared with the case of performing the laser annealing in the air atmosphere, but the grain size becomes small and the electrical characteristics of the TFT deteriorate.

On the other hand, after laser annealing is performed in the air atmosphere, hydrofluoric acid treatment is performed to remove the oxide film, and then laser annealing is performed in an inert gas atmosphere, so that the ridge is maintained while maintaining a large grain size. There is a report that can reduce.

[0017]

In semiconductor devices, contamination with metal impurities and organic substances has a great influence on electrical characteristics. Contamination of metal impurities causes defects such as poor oxide film withstand voltage and reduced carrier lifetime,
Lethal deterioration of electrical characteristics. For example, the surface of a silicon film is easily contaminated, and particularly a metal having a higher electronegativity than silicon takes electrons directly from silicon to chemically bond with silicon and is difficult to remove. Although metal atoms having a lower electronegativity than silicon are not directly adsorbed on the surface of the bare silicon film, they are more easily oxidized than silicon and are taken into the natural oxide film formed on the surface of the silicon film.

Organic contaminants affect the electrical properties of oxide films. Therefore, the dielectric strength is lowered by forming an oxide film after removing organic substances on the surface of the semiconductor film by a method such as cleaning with a mixed solution of sulfuric acid and hydrogen peroxide (hereinafter referred to as sulfuric acid / hydrogen peroxide mixture) or ozone water cleaning. can do. As the sulfuric acid / hydrogen peroxide mixture, a mixture of sulfuric acid H ₂ SO ₄ (97%) and hydrogen peroxide in a composition ratio of 4: 1 to 6: 1 is often used. In this case, both solutions are mixed and heat is generated at the same time,
Reach ~ 120 ° C. Further, the withstand voltage of the oxide film depends on the degree of contamination of organic substances, which causes characteristic variations. A large amount of organic substances exist in the clean room atmosphere,
The amount of organic substances adsorbed increases with time. A large amount of water is also present, and when adsorbed on the surface, it promotes natural oxide film growth,
It can also be contaminated by metals and organics dissolved in water.

When crystallization is performed by laser annealing after the metal element is introduced into the amorphous semiconductor film and the heat treatment is performed, the natural oxide film formed on the surface of the semiconductor film is preprocessed for laser annealing. Although removal is required, the surface of the semiconductor film is easily contaminated by impurities and is difficult to remove. Contamination of the semiconductor film greatly affects the electrical characteristics of a thin film transistor (TFT) using the semiconductor film as an active layer. This may cause variations in electrical characteristics.

Therefore, according to the present invention, a natural oxide film which causes contamination and variations during laser annealing is removed, and impurity contamination on the surface of the semiconductor film, which is apt to be contaminated, is reduced. The purpose is to suppress variations in the electrical characteristics of the formed TFT and improve the characteristics.

Further, after performing the first laser annealing in the air atmosphere, performing hydrofluoric acid treatment to remove the oxide film, and then performing the second laser annealing in the inert gas atmosphere, a large crystal grain diameter is obtained. Although it has been reported that the ridge can be reduced while keeping the same, this method has a problem in productivity and throughput because the atmosphere at the time of laser annealing must be changed between the first and second times.

Therefore, the present invention efficiently manufactures a semiconductor film with a reduced ridge without changing the atmosphere during laser annealing, and suppresses variations in electrical characteristics of TFTs manufactured based on this semiconductor film, The purpose is to improve the characteristics.

Further, in the current apparatus, it is necessary to perform the laser annealing pretreatment and the laser annealing treatment by different apparatuses, and there is a problem that performing the processing by using a plurality of apparatuses greatly lowers the productivity and the throughput. .

Therefore, in the present invention, a decrease in productivity and throughput is minimized, and a crystalline semiconductor film with reduced impurity contamination and a semiconductor film with reduced ridges are produced, and the semiconductor film is produced based on this semiconductor film. The purpose is to suppress variations in the electrical characteristics of the formed TFT and improve the characteristics.

[0025]

In order to solve the above problems, according to the present invention, when a laser annealing is performed after a metal element is introduced into an amorphous semiconductor film and a heat treatment is performed, after removing a natural oxide film. It is characterized in that the semiconductor film surface is covered with a clean oxide film by performing an oxidation treatment (preferably an oxidation treatment having an organic substance removing effect) and then laser annealing is performed to reduce impurity contamination on the semiconductor film surface.

As the oxidation treatment, ozone water treatment or irradiation with UV light in an oxygen atmosphere, sulfuric acid / hydrogen peroxide treatment, or other oxidation treatment having an organic substance removing effect is used to form a TFT.
It is possible to reduce organic contaminants on the surface of the semiconductor film, which causes variations in the electrical characteristics, and further stabilize the characteristics.

Specifically, a trace amount of an element (for example, a metal element that promotes crystallization) is introduced into an amorphous semiconductor film formed on an insulating substrate, and heat treatment is performed to perform the amorphous semiconductor. Crystallize part or all of the film. Then, hydrofluoric acid or buffer hydrofluoric acid diluted to an appropriate concentration or hydrofluoric acid treatment (etching treatment) using an etching solution containing hydrofluoric acid is performed to obtain a crystalline semiconductor film whose composition and film thickness are not controlled. The native oxide film on the surface and the localized metal element are removed. Further, laser annealing is performed after the surface of the semiconductor film is covered with a clean oxide film by performing an ozone water treatment, UV light irradiation in an oxygen atmosphere, or oxidation treatment having an organic substance removing effect such as sulfuric acid / hydrogen peroxide treatment. The surface of the semiconductor film exposed by the removal of the oxide film is easily contaminated as described above, but compared with this, the oxide film only physically adsorbs to the surface, and thus the surface of the semiconductor film is coated with the oxide film in this manner. By doing so, impurity contamination can be reduced, and T
It is possible to reduce variations in the electrical characteristics of the FT and stabilize the FT.

Further, in the present invention, the laser treatment for performing the continuous treatment while the substrate is kept in the nitrogen atmosphere while the hydrofluoric acid treatment, the oxidation treatment, the heat treatment and the laser annealing treatment as the laser annealing pretreatment are performed in any order in any order. It is characterized by using a device.

Further, according to the present invention, the first step of introducing a metal element into the amorphous semiconductor film formed on the substrate and the first crystalline semiconductor film obtained by subjecting the amorphous semiconductor film to the heat treatment. A second step of forming an oxide film, a third step of removing an oxide film formed on the surface of the first crystalline semiconductor film, and a first step of
Fourth step of forming a clean oxide film by subjecting the crystalline semiconductor film to an oxidation treatment having an organic substance removing effect, and irradiating the first crystalline semiconductor film with a laser beam in an inert atmosphere to form a clean oxide film. And a fifth step of forming the crystalline semiconductor film of 2.

Further, according to the present invention, the first step of introducing a metal element into the amorphous semiconductor film formed on the substrate and the heat treatment of the amorphous semiconductor film to form the first crystalline semiconductor film are performed. A second step of forming, a third step of removing the oxide film formed on the surface of the first crystalline semiconductor film, and an oxidation treatment having an organic substance removing effect on the first crystalline semiconductor film. A fourth step of forming a clean oxide film, and irradiating the first crystalline semiconductor film with a laser beam in an inert gas atmosphere having an oxygen concentration of 20 ppm or less to form a second crystalline semiconductor film. And a fifth step.

Further, according to the present invention, the first step of introducing a metal element into the amorphous semiconductor film formed on the substrate and the heat treatment of the amorphous semiconductor film to form the first crystalline semiconductor film. A second step of forming, a third step of removing the oxide film formed on the surface of the first crystalline semiconductor film, and an oxidation treatment having an organic substance removing effect on the first crystalline semiconductor film. A fourth step of forming a clean oxide film, and irradiating the first crystalline semiconductor film with a laser beam in an inert gas atmosphere having an oxygen concentration of 20 ppm or less to form a second crystalline semiconductor film. A fifth step, a sixth step of removing the oxide film formed on the surface of the second crystalline semiconductor film, and a second crystalline semiconductor film in an inert gas atmosphere having an oxygen concentration of 20 ppm or less. And a seventh step of irradiating with a laser beam And butterflies.

In the above invention, the third step is a step of removing the oxide film with hydrofluoric acid, and the fourth step is a step of forming an oxide film by applying ozone water. Is characterized by.

In the above invention, the third step is a step of removing the oxide film with hydrofluoric acid, and the fourth step is a step of forming the oxide film by irradiating with UV light. Is characterized by.

In the above invention, the third step is a step of removing the oxide film with hydrofluoric acid, and the fourth step is a step of forming the oxide film by applying sulfuric acid / hydrogen peroxide mixture. It is characterized by

Further, in the above invention, the inert gas atmosphere is any one of nitrogen, hydrogen and a rare gas.

Further, in the above invention, the amorphous semiconductor film is an amorphous silicon film.

Further, in the above invention, the first crystalline semiconductor film is a crystalline silicon film.

In the above invention, the second crystalline semiconductor film is a crystalline silicon film.

Further, according to the present invention, an oxide film removing chamber for removing an oxide film formed on the surface of the first crystalline semiconductor film formed on the substrate, and an organic substance on the surface of the first crystalline semiconductor film are provided. An oxidation treatment chamber for removing and performing an oxidation treatment and a laser treatment chamber for irradiating the first crystalline semiconductor film with a laser beam to form a second crystalline semiconductor film are provided.

Further, according to the present invention, an oxide film removing chamber for removing an oxide film formed on the surface of the first crystalline semiconductor film formed on the substrate and an organic substance on the surface of the first crystalline semiconductor film are provided. As a means for removing and oxidizing, there is provided an oxidation treatment chamber having a chemical solution nozzle, and a laser treatment chamber for irradiating the first crystalline semiconductor film with a laser beam to form a second crystalline semiconductor film. Characterize.

Further, according to the present invention, an oxide film removing chamber for removing an oxide film formed on the surface of the first crystalline silicon film formed on the substrate and an organic substance on the surface of the first crystalline semiconductor film are provided. An oxidation treatment chamber having means for irradiating UV light as a means for removing and oxidizing, and a laser treatment chamber for irradiating a laser beam on the first crystalline semiconductor film to form a second crystalline semiconductor film, It is characterized by having.

Further, according to the present invention, an oxide film removing chamber for removing an oxide film formed on the surface of the first crystalline semiconductor film formed on the substrate and an organic substance on the surface of the first crystalline semiconductor film are provided. An oxidation treatment chamber having a chemical solution nozzle as a means for removing and oxidizing, and an oxygen concentration of 20 p in the first crystalline semiconductor film.
and a laser processing chamber for forming a second crystalline semiconductor film by irradiating a laser beam in an atmosphere of an inert gas of pm or less.

Further, according to the present invention, an oxide film removing chamber for removing an oxide film formed on the surface of the first crystalline semiconductor film formed on the substrate and an organic substance on the surface of the first crystalline semiconductor film are provided. An oxidation treatment chamber having means for irradiating with UV light as means for removing and oxidizing, and a laser beam for irradiating the first crystalline semiconductor film with a laser beam in an inert gas atmosphere having an oxygen concentration of 20 ppm or less are used. And a laser treatment chamber in which a crystalline semiconductor film is formed.

Further, in the above invention, the semiconductor manufacturing apparatus has a transfer chamber having a mechanism for transferring a substrate, and the oxide film removal chamber, the oxidation processing chamber and the laser processing chamber are connected to the transfer chamber via a gate valve. It is characterized by

Further, in the above invention, the chemical liquid nozzle is a nozzle for injecting ozone water or a mixed liquid of sulfuric acid and hydrogen peroxide.

Further, in the present invention, by using the laser processing apparatus, the substrate has an oxygen concentration of 20 ppm during the step of performing the laser annealing in the inert gas atmosphere after removing the natural oxide film and then performing the oxidation processing. It is characterized by being held in the following inert gas atmosphere. As a result, the time during which the semiconductor film surface is exposed can be shortened, the laser annealing can be completed without exposing the semiconductor film surface to the contaminated atmosphere, and the electrical characteristics of the TFT can be further improved. , The inert gas atmosphere is
It is either nitrogen, hydrogen or a noble gas. The rare gas is any of argon, neon, helium, xenon or krypton.

Further, in the present invention, when laser annealing is carried out, after removing the natural oxide film, an oxidation treatment is applied to cover with the oxide film, laser annealing is carried out in an inert gas atmosphere, and then a further step is performed. It is characterized in that a semiconductor film with a reduced ridge is efficiently manufactured without changing the atmosphere during laser annealing by performing an acid treatment and then performing a laser annealing in an inert gas atmosphere.

Further, in the present invention, by using the laser processing apparatus, the natural oxide film is removed, the oxidation processing is performed, the laser annealing is performed in the inert gas atmosphere, and the hydrofluoric acid processing is further performed. It is characterized in that the substrate is kept in an inert gas atmosphere having an oxygen concentration of 20 ppm or less during the step of performing laser annealing in an inert gas atmosphere after the first step. As a result, a semiconductor film with reduced ridges and reduced impurities can be efficiently manufactured.

In the above invention, the metal element is N
i, Pd, Pt, Cu, Ag, Au, Al, In, Sn
Alternatively, if one or more kinds of elements selected from Pd are used, good crystal growth can be achieved.

In the above invention, the metal element is 8
It is preferable that one or a plurality of kinds of elements selected from the group 11, group 13, group 13, group 14 or group 15 elements will allow good crystal growth.

A detailed physical property analysis of a semiconductor film formed by using the present invention is performed, and its characteristics are shown below.

The technique used for the physical property analysis is EBSP (Elec
tron Back Scatter DiffractionPattern) analysis. By scanning the electron beam and analyzing the Kikuchi pattern obtained by backscattering, the orientation of the film in a minute region can be investigated in detail.

FIG. 16 shows a typical analysis result. Also,
FIG. 17 shows the result of evaluating a general poly-Si film obtained by crystallizing a-Si only by an excimer laser without using the present invention.
This is the result of analysis using a method called unique grain mapping. Specifically, the sample was scanned with an electron beam to determine the orientation at each point, and the deviation between the adjacent orientations at each measurement point was less than 15 degrees, which was indicated by the same color.

As a result, a clear difference was observed between the semiconductor film of the present invention and the semiconductor film generally called low temperature poly-Si crystallized only by laser (hereinafter referred to as LPS film). In low-temperature poly-Si, almost random orientations are observed at each measurement point, but in the semiconductor film of the present invention, regions in which the misalignment of the orientations is small are adjacent to each other and form a set having a size of about several μm. Was observed.

The LPS film evaluation result is the result of evaluation at intervals of 0.2 μm, which is 0.2 μm.
It is shown that the crystal grain having the following grain size has a high-angle grain boundary of 15 degrees or more at the grain boundary.

On the other hand, in the semiconductor film of the present invention, poly-Si having a grain size of several μm or crystal grains having a small tilt grain boundary of less than 15 degrees are gathered to form a region of several μm in size. (Hereinafter referred to as a domain) is formed. According to the SEM observation (FIG. 18) of the semiconductor film of the present invention, a grain size of several μm was not observed, and crystal grain boundaries were observed at intervals of several hundred nm. It was found to be a set of crystal grains having.

The small-angle grain boundaries have a smaller number of defects (silicon dangling bonds) contained in the grain boundaries and a smaller electric barrier than the large-angle grain boundaries. In other words, the inside of the domain is approximately close to a single crystal, and the larger the domain, the better the characteristics.

19 and 20 show the relationship between the domain diameter and the characteristics of the TFT manufactured using the domain diameter. The correlation between the S value and field effect mobility of the TFT and the domain diameter is shown respectively. The domain diameter was defined as the diameter of a circle having the average area calculated by calculating the average area of the domain. Domain diameter is 1 μm
It can be seen that very good characteristics are obtained at the above (desirably 5 μm or more). That is, it has been clarified that the smaller the number of high-angle grain boundaries crossing, the better the characteristics obtained.

If the domain diameter is 1 μm, about 1 or less large-angle grain boundaries are crossed per 1 μm with respect to a linear current path. Naturally, it crosses a larger number of small-angle grain boundaries, but the influence is small because the electrical barrier is small.

The results of the above analysis will be summarized. A polycrystalline semiconductor film is used as an active layer, the active layer includes a high-angle grain boundary and a low-angle grain boundary, and the number of grain boundaries crossed when a current flows through the active layer is large per current path length of 1 μm. The number of tilt angle boundaries is 1 or less and the number of low angle grain boundaries is 1 or more, and the misorientation grain boundaries have an orientation deviation of less than 15 °.

A polycrystalline semiconductor film is used as an active layer, and the active layer includes a high-angle grain boundary and a low-angle grain boundary, and an average diameter of a set of crystal grains having a low-angle grain boundary is 1 μm or more.
The low-angle grain boundaries have an orientation deviation of less than 15 ° at the grain boundaries.

In particular, the number of large-angle grain boundaries per 1 μm of the current path length is 0.2 or less.

In particular, the average diameter of the aggregate of the crystal grains is 5 μm or more.

[0064]

BEST MODE FOR CARRYING OUT THE INVENTION [Embodiment 1] When laser annealing is performed after a metal element is introduced into an amorphous semiconductor film and heat treatment is performed, a natural oxide film is removed and then an oxidation treatment is performed, and then laser irradiation is performed. A method for manufacturing a crystalline semiconductor film with reduced impurity contamination by annealing will be described with reference to FIGS. Note that the amorphous semiconductor film is an amorphous silicon film and the crystalline semiconductor film is a crystalline silicon film.

First, the base insulating film 102 is formed on the substrate 101. As the base film 102, an insulating film such as a silicon oxide film, a silicon nitride film, or a silicon nitride oxide film is formed. Although an example of using a single layer structure as the base film 102 is shown here, a structure in which two or more layers of the insulating film are stacked may be used.

Next, the semiconductor film 1 is formed on the base insulating film 102.
03 is deposited. As the semiconductor film 103, a semiconductor film having an amorphous structure is formed by known means (sputtering method, LPCVD method,
Alternatively, a film is formed by a plasma CVD method or the like. The semiconductor film 103 has a thickness of 25 to 80 nm (preferably 30 to
A film having a thickness of 60 nm is formed. (Fig. 2 (a)) Then,
A trace amount of element (for example, a metal element that promotes crystallization such as nickel) is introduced into the semiconductor film 103, and heat treatment is performed. By the heat treatment, part or all of the semiconductor film is crystallized, so that the crystalline semiconductor film 104 is obtained.

The crystalline semiconductor film 104 obtained by the heat treatment is annealed by a laser beam. First, hydrofluoric acid diluted to an appropriate concentration (about 0.2 to 1%) is used for jetting for 30 to 90 seconds, and hydrofluoric acid treatment (etching treatment) is performed to remove the oxide film. In this embodiment,
Using hydrofluoric acid having a concentration of 0.5%, the hydrofluoric acid was sprayed on the processed substrate for 70 seconds while rotating the processed substrate to form the oxide film 1.
05 is removed (FIG. 2 (b)), (FIG. 2 (c)). After removing the oxide film, the surface of the semiconductor film is rinsed with pure water to be cleaned. In this step, the native oxide film 105 and the localized metal element on the surface of the crystalline semiconductor film whose composition and film thickness are not controlled are removed. Further, prior to the hydrofluoric acid treatment, impurities such as metal elements on the surface of the semiconductor film are oxidized using a solvent having a strong oxidizing power such as ozone water, and the impurities are removed by etching with an etchant containing hydrofluoric acid. The effect of removing impurities can also be enhanced. Further, after performing an oxidation treatment (preferably an oxidation treatment having an organic substance removing effect) to form an oxide film 106 on the semiconductor film 104 (FIG. 2D),
Laser annealing is performed by irradiating a laser beam (Fig. 2
(E)). As the oxidation treatment, for example, ozone water treatment, UV light irradiation in an oxygen atmosphere, or sulfuric acid / hydrogen peroxide treatment may be performed. Laser annealing is preferably performed in an inert gas atmosphere (for example, a nitrogen atmosphere) having an oxygen concentration of 20 ppm or less. In addition to nitrogen, either hydrogen or a rare gas may be used. The rare gas is any of argon, neon, helium, xenon or krypton.

A laser oscillator used in the laser annealing method will be described. Excimer lasers are widely used because of their high output and the ability to oscillate highly repetitive pulses of about 300 Hz at present. In addition to the pulsed excimer laser, a continuous wave excimer laser or A
An r laser, a YAG laser, or the like can also be used.

FIG. 1 (B) shows that in the step 3 of FIG. 1 (A), the treatment of (a) is performed as a pretreatment of the laser annealing: cleaning with ozone water (hydro-cleaning) and then hydrofluoric acid treatment (HF). Vg-Id characteristics of TFTs in which the crystalline semiconductor film subjected to the treatment) and the treatment of (b): the crystalline semiconductor film subjected to the ozone water treatment (hydrowashing) after the hydrofluoric acid treatment was used as the active layer, respectively. Is. The TFT using a crystalline semiconductor film as an active layer (hydro-cleaning + HF treatment + hydro treatment) (treatment of (b)) is a TFT using a crystalline semiconductor film as an active layer (hydro-cleaning + HF treatment) ((a) Processing)
It can be seen that the variation of the threshold voltage is obviously smaller than that of.

Further, the TFT (hydro-cleaning + HF treatment + hydro treatment) using the crystalline semiconductor film as the active layer is the TFT (hydro-cleaning + HF treatment) using the crystalline semiconductor film as the active layer.
It can be seen that a higher mobility is obtained and the electrical characteristics of the TFT are also improved compared to the (treatment).

In this way, a crystalline semiconductor film with reduced impurity contamination is produced, and a TFT is formed based on the crystalline semiconductor film.
When the above is manufactured, variations in the electrical characteristics of the TFT are reduced and the characteristics are improved.

[Embodiment 2] After laser annealing is performed by the same method as in Embodiment 1, hydrofluoric acid treatment is further performed, and then laser annealing is performed in an inert gas atmosphere to increase the height of the ridge on the film surface. A method for forming a crystalline silicon film with reduced thickness will be described with reference to FIGS.

A base insulating film 112 and a semiconductor film 113 are formed on the substrate 111 by the same method as in Embodiment 1, a trace amount of element is introduced into the semiconductor film, and heat treatment is performed (FIG. 4).
(A)). The crystalline semiconductor film 114 is obtained by the heat treatment. As a pretreatment for laser annealing, hydrofluoric acid treatment is performed to remove the native oxide film 115 (see FIG. 4).
(B)), (FIG. 4C), an oxidation treatment (preferably an oxidation treatment having an organic substance removing effect) is performed to perform the semiconductor film 114.
After forming the oxide film 116 on the upper surface (FIG. 4D), the first laser annealing is performed by irradiating a laser beam in an inert gas atmosphere having an oxygen concentration of 20 ppm or less (for example, in a nitrogen atmosphere) (FIG. 4). (E)), a crystalline semiconductor film 117 is obtained (FIG. 4 (f)). As the oxidation treatment, for example, ozone water treatment, UV light irradiation in an oxygen atmosphere, or sulfuric acid / hydrogen peroxide treatment may be performed.

Next, the hydrofluoric acid treatment is performed again to remove the oxide film, and the laser beam is irradiated in an inert gas atmosphere (for example, nitrogen atmosphere) having an oxygen concentration of 20 ppm or less to produce a second
Laser annealing is performed (FIG. 4G).

By the second laser annealing, it is possible to obtain a crystalline semiconductor film in which the height of the ridge on the film surface is reduced while maintaining the crystal grain diameter obtained by the first laser annealing.

When a crystalline semiconductor film in which the height of the ridge on the film surface is reduced is manufactured by the above method and a TFT is manufactured based on the crystalline semiconductor film, the electrical characteristics of the TFT are improved. .

[Embodiment 3] A laser processing apparatus for carrying out continuous processing while the substrate is kept in an inert gas atmosphere between the laser annealing pretreatment and the laser annealing in Embodiments 1 and 2 will be described with reference to FIG. To do.

Reference numeral 121 denotes a carry-in / carry-out chamber for carrying in / carrying out a substrate (sample), which has a large number of substrates on which a silicon film to be irradiated with a laser beam or a thin film transistor in a state of a manufacturing process is formed. It is stored in the sheet cassette 122. Substrate loading / unloading chamber 121
When the substrate is taken in and out from the outside, the cassette 122 accommodating the substrate is moved.

Reference numeral 123 denotes a transfer chamber for transferring the substrates in the apparatus, which is provided with a robot arm 124 for transferring the substrates one by one.

Further, reference numeral 125 is an alignment means for aligning the substrate, which has a function of accurately aligning the robot arm with the substrate.

The chamber designated by 126 is a chamber for irradiating the substrate with a laser beam. In this chamber, the laser beam emitted from the laser irradiation device can be emitted to the substrate arranged on the stage 127 on which the substrate is placed, through the synthetic quartz window. Stage 127
As shown by the arrow, it has a function of moving in a one-dimensional direction.

The laser irradiation device has a function of oscillating a XeCl excimer laser, for example, and has an optical system as shown in FIG. The laser beam is shaped into a linear beam by passing through the optical system shown in FIG.

First, the side view of FIG. 3 will be described. The laser beam emitted from the laser oscillator 1001 is split by the cylindrical array lenses 1002a and 1002b in the direction perpendicular to the traveling direction of the laser beam. In the present specification, the direction will be referred to as the vertical direction. The vertical direction shall be bent in the direction of the light bent by the mirror when the mirror enters in the middle of the optical system. In this configuration, there are four divisions. These divided laser beams are once combined into one laser beam by the cylindrical array lens 1004. The laser beam is reflected by the mirror 1007, and then is converged into one laser beam again by the doublet cylindrical lens 1008 on the irradiation surface 1009. The doublet cylindrical lens is a lens composed of two cylindrical lenses. Thereby, the energy homogenization in the width direction and the length in the width direction of the linear beam are determined.

Next, the top view of FIG. 3 will be described. The laser beam emitted from the laser oscillator 1001 is split by the cylindrical array lens 1003 in a direction perpendicular to the traveling direction of the laser beam and a direction perpendicular to the vertical direction. This direction will be referred to as the lateral direction in this specification. It is assumed that the lateral direction bends in the direction of light bent by the mirror when the mirror enters in the middle of the optical system.
In this configuration, there are 7 divisions. Then, with the cylindrical lens 1005, the laser beam is irradiated on the irradiation surface 1009.
Combined into one. This determines the homogenization and length of the energy in the lengthwise direction of the linear beam.

The chamber indicated by 128 is an oxide film removing chamber for performing hydrofluoric acid treatment on the substrate by the spinner. The spinner 131 has a chuck mechanism for supporting the substrate and can be rotated at a designated rotation speed. Further, it has a plurality of chemical solution nozzles 132 for ejecting hydrofluoric acid and pure water to jet them onto the substrate.

The chamber denoted by 129 is an oxide film forming chamber (oxidation chamber) for subjecting the substrate to oxidation treatment, and the spinner 139 has a chuck mechanism for supporting the substrate.
It can be rotated at a specified rotation speed of 100 to 3000 rpm. Further, it has a plurality of chemical solution nozzles 140 for ejecting ozone water and pure water and ejecting it onto the substrate. The means for removing the organic substance and forming the oxide film is not limited to the chemical solution nozzle, and means for irradiating UV light may be used.

The chamber indicated by 130 is a heating chamber for heating the substrate, and the stage 133 has a built-in resistance heating means so that the substrate can be heated to a predetermined temperature.

Each chamber has a closed structure and can be brought into a depressurized state or a high vacuum state by an exhaust system. Each exhaust system is independently equipped with a vacuum pump. Further, each chamber is provided with a gas supply system for supplying a required gas (for example, an inert gas). In addition, each chamber is provided with gate valves 134 to 138, and is configured to independently enhance the airtightness of each chamber.

If the apparatus as described above is used, the first embodiment
During the steps of hydrofluoric acid treatment, oxidation treatment and laser annealing in the above, the substrate can be kept in an inert gas atmosphere having an oxygen concentration of 20 ppm or less, and a crystalline semiconductor film with reduced impurity contamination can be manufactured using the above apparatus. However, when a TFT is manufactured based on the crystalline semiconductor film, variations in electrical characteristics of the TFT are reduced and characteristics are improved.

By using the above apparatus, the substrate is placed in an inert gas atmosphere having an oxygen concentration of 20 ppm or less during the steps of hydrofluoric acid treatment, oxidation treatment, laser annealing, oxidation treatment and laser annealing in the second embodiment. When a crystalline semiconductor film in which the height of the ridge on the film surface is reduced and impurity contamination is reduced by using the device, and a TFT is produced based on the crystalline semiconductor film, Variations in the electrical characteristics of the TFT are reduced and the characteristics are improved.

The present invention having the above structure will be described in more detail with reference to the following examples.

[0092]

Example 1 An amorphous silicon film is used as an amorphous semiconductor film, and a natural oxide film is used when laser annealing is performed after heat treatment by introducing a metal element into the amorphous silicon film. A method for manufacturing a crystalline silicon film with reduced impurity contamination by performing a laser annealing process after oxidizing the semiconductor film with ozone water after removing the above will be described with reference to FIG.

A Corning 1737 substrate having a thickness of 0.7 mm and a size of 5 inches was prepared as a substrate. As shown in FIG. 2A, a plasma CVD apparatus is used for the substrate 101,
A 200 nm thick silicon oxynitride film 102 is formed, and a 50 nm thick amorphous silicon film 1 is formed on the surface of the silicon oxynitride film 102.
03 was deposited. A solution containing an element that promotes crystallization is applied onto the amorphous silicon film. As the solution,
For example, when a nickel acetate solution is used, the nickel acetate solution (concentration in terms of weight: 10 ppm, volume: 5 ml) is applied to the entire surface of the film by spin coating. Then, the substrate was heated in a nitrogen atmosphere at a temperature of 500 ° C. for 1 hour and further in a nitrogen atmosphere at a temperature of 550 ° C. for 4 hours. By the heat treatment, as shown in FIG. 2B, the crystalline silicon film 10 is formed.
4 is obtained.

Next, as a pretreatment for laser annealing, hydrofluoric acid treatment (etching treatment) is performed. As shown in FIG. 2C, a natural oxide film 105 of a crystalline silicon film of which composition and film thickness are not controlled and a localized metal element is formed by using hydrofluoric acid having a concentration of 0.5%. While rotating, hydrofluoric acid is sprayed on the treated substrate for 70 seconds to remove it.
After that, as shown in FIG. 2D, about 1 to 2 nm is obtained by performing an oxidation treatment by applying ozone water at 500 rpm for about 20 to 40 seconds by spin coating using ozone water with an ozone concentration of 6 to 15 mg / l. Silicon oxide film 1
06 is formed. This silicon oxide film 106 is a silicon film surface 1
04 has the effect of reducing impurity contamination.

After that, a laser beam is irradiated in a nitrogen atmosphere using a XeCl excimer laser (wavelength 308 nm, pulse width 30 ns) L3308 manufactured by Lambda Co., thereby performing laser annealing. This laser oscillator emits a pulsed laser and has an ability to generate energy of 500 mJ / pulse. The size of the laser beam is 10 × 30 mm at the exit of the laser beam (both full width at half maximum in the beam profile). XeC
A laser beam is processed into a linear beam through an optical system as shown in FIG. 3 using an l-excimer laser, and laser annealing is performed.

A crystalline silicon film with reduced impurity contamination was produced by the above method, and TF was formed based on the crystalline silicon film.
When T is manufactured, variations in the electrical characteristics of the TFT are reduced and the characteristics are improved. Example 2 An amorphous silicon film is used as the amorphous semiconductor film,
When laser annealing is performed after introducing a metal element into the amorphous silicon film and performing heat treatment, after removing the natural oxide film, the semiconductor film is oxidized by UV light irradiation in an oxygen atmosphere. A method of performing laser annealing to form a crystalline silicon film with reduced impurity contamination will be described with reference to FIG.

In the same manner as in Example 1, a silicon nitride oxide film 102 and an amorphous silicon film 103 were formed on a substrate 101 as shown in FIG. 2A, and a crystal was formed on the amorphous silicon film 103. A solution containing an element that accelerates the conversion is applied. Next, the substrate is placed in a nitrogen atmosphere at a temperature of 500 ° C. for 1 hour and further at a temperature of 55.
Heating was performed for 4 hours in a nitrogen atmosphere at 0 ° C. By the heat treatment, a silicon film 104 having crystallinity is obtained as shown in FIG.

Next, as a pretreatment for the laser annealing, a hydrofluoric acid treatment is performed, and as shown in FIG.
5 is removed, and then the substrate temperature is set to 2 in oxygen atmosphere.
By irradiating UV light for 30 to 120 seconds at 00 ° C., a silicon oxide film 106 of about 1 to 2 nm is formed as shown in FIG. The silicon oxide film 106 is the silicon film 1.
04 has the effect of covering the surface and reducing impurity contamination.
Thereafter, laser annealing is performed by irradiating a laser beam with a XeCl excimer laser in a nitrogen atmosphere in the same manner as in Example 1 as shown in FIG.

A crystalline silicon film with reduced impurity contamination was produced by the above method, and TF was formed based on the crystalline silicon film.
When T is manufactured, variations in the electrical characteristics of the TFT are reduced and the characteristics are improved. Example 3 An amorphous silicon film is used as an amorphous semiconductor film,
When laser annealing is performed after introducing a metal element into the amorphous silicon film and performing heat treatment, the natural oxide film is removed and then the semiconductor film is oxidized with sulfuric acid / hydrogen peroxide solution before laser annealing. A method for manufacturing a crystalline silicon film with reduced impurity contamination will be described with reference to FIG.

In the same manner as in Example 1, a silicon nitride oxide film 102 and an amorphous silicon film 103 were formed on a substrate 101 as shown in FIG. 2A, and a crystal was formed on the amorphous silicon film 103. A solution containing an element that accelerates the conversion is applied. Next, the substrate is placed in a nitrogen atmosphere at a temperature of 500 ° C. for 1 hour and further at a temperature of 55.
Heating was performed for 4 hours in a nitrogen atmosphere at 0 ° C. By the heat treatment, a silicon film 104 having crystallinity is obtained as shown in FIG.

Next, as a pretreatment for laser annealing, hydrofluoric acid treatment is performed to remove the natural oxide film 105 on the surface of the crystalline silicon film as shown in FIG.
By performing an oxidation treatment by applying for about 60 seconds, a silicon oxide film 106 having a thickness of about 1 to 2 nm is formed as shown in FIG. The silicon oxide film 106 covers the surface of the silicon film 104 and has an effect of reducing impurity contamination. In this embodiment, the volume ratio H ₂ SO ₄ : H is used as the sulfuric acid / hydrogen peroxide mixture.
₂ O ₂ : H ₂ O = 95: 31: 74 was used, and the liquid temperature was 6
It is about 0 to 80 ° C. Thereafter, laser annealing is performed by irradiating a laser beam with a XeCl excimer laser in a nitrogen atmosphere in the same manner as in Example 1 as shown in FIG.

A crystalline silicon film with reduced impurity contamination was produced by the above method, and TF was formed based on the crystalline silicon film.
When T is manufactured, variations in the electrical characteristics of the TFT are reduced and the characteristics are improved. [Example 4] As a pretreatment of laser annealing, after removing the natural oxide film, the semiconductor film was oxidized using ozone water, laser annealing was performed, and hydrofluoric acid treatment was further performed, followed by a nitrogen atmosphere. A method of manufacturing a crystalline silicon film in which the height of the ridge on the film surface is reduced by performing laser annealing will be described with reference to FIG.

As shown in FIG. 4A, a silicon nitride oxide film 112 and an amorphous silicon film 113 are formed on the substrate 111 in the same manner as in Example 1, and the amorphous silicon film 113 is crystallized. A solution containing an element that accelerates the conversion is applied. Next, the substrate is placed in a nitrogen atmosphere at a temperature of 500 ° C. for 1 hour and further at a temperature of 55.
Heating was performed for 4 hours in a nitrogen atmosphere at 0 ° C. By the heat treatment, a silicon film 114 having crystallinity is obtained as shown in FIG.

As a pretreatment for laser annealing in the same manner as in Example 1, hydrofluoric acid treatment was carried out to remove the natural oxide film 115 as shown in FIG. 4C, and then ozone water treatment was carried out. Silicon oxide film 1 as shown in FIG.
16 is formed.

After that, XeCl 2 was formed in the same manner as in Example 1.
Laser annealing is performed by irradiating a laser beam with an excimer laser in a nitrogen atmosphere as shown in FIG.

Next, hydrofluoric acid treatment is performed again to remove the silicon oxide film and expose the crystalline silicon film 117 as shown in FIG. 4 (f). Then, as shown in FIG. 20p
Laser annealing is performed by irradiating a laser beam in a nitrogen atmosphere of pm or less. By this laser annealing, the silicon film 1
17 The height of the ridge on the surface is reduced.

When a crystalline semiconductor film in which the height of the ridge on the film surface is reduced is manufactured by the above method and a TFT is manufactured based on the crystalline semiconductor film, the electrical characteristics of the TFT are improved. . [Embodiment 5] In this embodiment, a laser processing apparatus used for carrying out the invention disclosed in this specification will be described. A case where ozone water treatment is used as the oxidation treatment will be described with reference to FIG. FIG. 5 is a top view of the laser processing apparatus.

Reference numeral 121 denotes a carry-in / carry-out chamber for carrying in / carrying out a substrate (sample), in which a large number of substrates on which a silicon film to be irradiated with a laser beam or a thin film transistor in a state of a manufacturing process is formed It is stored in the sheet cassette 122. Substrate loading / unloading chamber 121
When the substrate is taken in and out from the outside, the cassette 122 accommodating the substrate is moved.

Reference numeral 123 denotes a transfer chamber for transferring the substrates in the apparatus, which is provided with a robot arm 124 for transferring the substrates one by one.

Further, reference numeral 125 denotes an alignment means for aligning the substrate, which has a function of accurately aligning the robot arm and the substrate.

The chamber indicated by 126 is a chamber for irradiating the substrate with a laser beam. In this chamber, the laser beam emitted from the laser irradiation device can be emitted to the substrate arranged on the stage 127 on which the substrate is placed, through the synthetic quartz window. Stage 127
As shown by the arrow, it has a function of moving in a one-dimensional direction.

The laser irradiation device has a function of oscillating, for example, a XeCl excimer laser and has a built-in optical system as shown in FIG. By passing through the optical system shown in FIG. 3, the laser beam has a width of several mm to several cm and a length of several tens of c.
It is shaped into a linear beam of m.

The chamber indicated by 128 is an oxide film removing chamber for performing hydrofluoric acid treatment on the substrate by the spinner. The spinner 131 has a chuck mechanism for supporting the substrate and can be rotated at a designated rotation speed of 100 to 3000 rpm. Further, it has a plurality of chemical solution nozzles 132 for ejecting hydrofluoric acid and pure water to jet them onto the substrate.

The chamber denoted by 129 is an oxidation treatment chamber for subjecting the substrate to oxidation treatment with ozone water. The spinner 139 has a chuck mechanism for supporting the substrate.
It can be rotated at a designated rotation speed of 00 to 3000 rpm. Further, it has a plurality of chemical solution nozzles 140 for ejecting ozone water and pure water and ejecting it onto the substrate.
The means for removing the organic substance and forming the oxide film is not limited to the chemical solution nozzle, and means for irradiating UV light may be used.

The chamber denoted by 130 is a heating chamber for heating the substrate, and the stage 133 has a built-in resistance heating means so that the substrate can be heated to a predetermined temperature.

Each chamber has a closed structure and can be brought into a depressurized state or a high vacuum state by an exhaust system. Each exhaust system is independently equipped with a vacuum pump. Further, each chamber is provided with a gas supply system for supplying a required gas (for example, an inert gas). In addition, each chamber is provided with gate valves 134 to 138, and is configured to independently enhance the airtightness of each chamber.

When ozone water is used for the oxidation treatment, for example, a chemical liquid nozzle for discharging ozone water and jetting it onto the substrate is added to the oxide film removing chamber 128 as a means for removing organic substances and forming an oxide film. Thus, the oxide film removal chamber 128 and the oxidation treatment chamber 129 can be used as the same chamber, and the number of chambers can be reduced and throughput can be improved. [Embodiment 6] In this embodiment, as a pretreatment for laser annealing, a natural oxide film is removed by hydrofluoric acid treatment, and then a semiconductor film is oxidized using ozone water, and then laser annealing is performed. A case where the substrate is held in a nitrogen atmosphere with an oxygen concentration of 20 ppm or less during the steps of removing the natural oxide film, oxidizing the semiconductor film, and laser annealing using the laser processing apparatus shown in FIG. 5 will be described with reference to FIG. .

As shown in FIG. 6A, a silicon nitride oxide film 142 and an amorphous silicon film 143 are formed on the substrate 141 by the same method as in Example 1, and the amorphous silicon film 143 is crystallized. A solution containing an element that accelerates the conversion is applied. Next, the substrate is placed in a nitrogen atmosphere at a temperature of 500 ° C. for 1 hour and further at a temperature of 55.
Heating was performed for 4 hours in a nitrogen atmosphere at 0 ° C. By the heat treatment, a crystalline silicon film 144 is obtained as shown in FIG.

Next, laser annealing pretreatment and laser annealing treatment are performed using the laser processing apparatus shown in the fifth embodiment. FIG. 5 is a top view of the laser processing apparatus. The gate valves are all closed, and the oxygen concentration in each chamber is 2
It is kept in a nitrogen atmosphere of 0 ppm or less.

First, the cassette 122 in which a large number of substrates having the state shown in FIG.
Store in 1. Next, the loading / unloading chamber 121 is set to an oxygen concentration of 20
A nitrogen atmosphere of ppm or less is used.

Then, the gate valve 134 is opened, and the robot arm 124 is used to load one substrate into the cassette 12
Then, the gate valve 134 is closed. Further, the gate valve 135 is opened and the substrate held by the robot arm 124 is moved to the oxide film removing chamber 12
8, and the gate valve 135 is closed.

In the oxide film removing chamber 128, the oxygen concentration of the substrate is set to 2
While maintaining a nitrogen atmosphere of 0 ppm or less, hydrofluoric acid was applied while rotating the substrate at 600 rpm with a spinner to remove the natural oxide film 145 as shown in FIG. 6C, and after washing with pure water, the rotation speed was 2500 rpm. Then, the substrate is dried. After that, the gate valve 135 is opened, the substrate is transferred to the transfer chamber 123 by the robot arm 124, and the gate valve 135 is closed. Then, the gate valve 137 is opened, the substrate held by the robot arm 124 is transferred to the oxidation treatment chamber 129, and the gate valve 137 is closed.

In the oxidation treatment chamber 129, the substrate is exposed to an oxygen concentration of 20.
While maintaining the nitrogen atmosphere at or below ppm, the spinner spins the substrate at 500 rpm while the ozone concentration is 6
By performing ozone water treatment for about 20 to 40 seconds using ozone water of about 15 mg / l, a silicon oxide film 146 of about 10 to 20 Å is formed as shown in FIG. 6D. The silicon oxide film 146 covers the silicon film surface 144 and has an effect of reducing impurity contamination.

After the oxidation treatment, the gate valve 137 is opened,
The substrate is transferred to the transfer chamber 123 by the robot arm 124, and the gate valve 137 is closed. After that, the substrate may be transferred to the heating chamber 130, and the substrate may be heated by the stage 133 having a means for heating the substrate to dry the residual moisture on the substrate. Then, open the gate valve 136,
The substrate is transferred to the chamber 126 for irradiating the laser beam by the robot arm 124, and the gate valve 136 is closed.

A laser beam having a linear shape is used.
The substrate stage 127 is arranged in the width direction of the linear laser beam.
Is moved to irradiate a laser beam onto a predetermined area. Here, in the state of FIG. 6E, the substrate stage 127 is moved so that the laser beam is swept from the right end to the left end of the drawing, and the laser beam is emitted. The moving speed of the substrate stage 127 here is 1 mm / sec.

After the irradiation of the laser beam is completed, the gate valve 136 is opened, the substrate is transferred to the transfer chamber 123 by the robot arm 124, and the gate valve 136 is closed. Then, the gate valve 134 is opened to load / unload the substrate 12
The cassette 122 in 1 is closed, and the gate valve 134 is closed.

By repeating the above operation, hydrofluoric acid treatment, oxidation treatment, and laser beam irradiation can be performed on all of the plurality of substrates housed in the cassette 122 in the carry-in / carry-out chamber 121. Then, after the hydrofluoric acid treatment, the oxidation treatment, and the laser beam irradiation on all the substrates are completed,
The substrates stored in the cassette 122 are taken out of the apparatus from the substrate loading / unloading chamber 121 for each cassette.

The silicon film thus manufactured is used as a TFT.
If the active layer is used, the variation in the electrical characteristics of the TFT is reduced and the characteristics are improved. [Embodiment 7] In this embodiment, as a pretreatment for laser annealing, the natural oxide film is removed, the semiconductor film is oxidized using ozone water, laser annealing is performed, and then hydrofluoric acid treatment is performed. When laser annealing is performed in a nitrogen atmosphere, oxygen is removed between the steps of natural oxide film removal, semiconductor film oxidation, laser annealing, hydrofluoric acid treatment, and laser annealing using the laser processing apparatus shown in the fifth embodiment. Concentration 20
A case where the substrate is held in a nitrogen atmosphere of ppm or less will be described with reference to FIG.

As shown in FIG. 7A, a silicon oxynitride film 152 and an amorphous silicon film 153 are formed on the substrate 151 in the same manner as in Example 1, and the amorphous silicon film 153 is crystallized. A solution containing an element that accelerates the conversion is applied. Next, the substrate is placed in a nitrogen atmosphere at a temperature of 500 ° C. for 1 hour and further at a temperature of 55.
Heating was performed for 4 hours in a nitrogen atmosphere at 0 ° C. By the heat treatment, a silicon film 154 having crystallinity is obtained as shown in FIG.

Next, laser annealing pretreatment and laser annealing treatment are performed using the laser processing apparatus shown in the fifth embodiment. FIG. 5 is a top view of the laser processing apparatus. The gate valves are all closed, and the oxygen concentration in each chamber is 2
It is kept in a nitrogen atmosphere of 0 ppm or less.

First, the cassette 122 in which a large number of substrates having the state shown in FIG.
Store in 1. Next, the loading / unloading chamber 121 is set to an oxygen concentration of 20
A nitrogen atmosphere of ppm or less is used.

Then, the gate valve 134 is opened, and the robot arm 124 is used to load one substrate into the cassette 12
Then, the gate valve 134 is closed. Further, the gate valve 135 is opened and the substrate held by the robot arm 124 is moved to the oxide film removing chamber 12
8, and the gate valve 135 is closed.

In the oxide film removing chamber 128, the oxygen concentration of the substrate is set to 2
While maintaining the nitrogen atmosphere at 0 ppm or less, the substrate was rotated at 600 rpm by a spinner to apply hydrofluoric acid to remove the natural oxide film 155 as shown in FIG. 7C, and after washing with pure water, the rotation speed was 2500 rpm. Then, the substrate is dried. After that, the gate valve 135 is opened, the substrate is transferred to the transfer chamber 123 by the robot arm 124, and the gate valve 135 is closed. Then, the gate valve 137 is opened, the substrate held by the robot arm 124 is transferred to the oxidation treatment chamber 129, and the gate valve 137 is closed.

In the oxidization processing chamber 129, the substrate has an oxygen concentration of 20.
While maintaining the nitrogen atmosphere at or below ppm, the spinner spins the substrate at 500 rpm while the ozone concentration is 6
By performing ozone water treatment for about 20 to 40 seconds using ozone water of about 15 mg / l, a silicon oxide film 156 of about 10 to 20 Å is formed as shown in FIG. 7D. The silicon oxide film 156 covers the silicon film surface 154 and has an effect of reducing impurity contamination.

After the oxidation treatment, the gate valve 137 is opened,
The substrate is transferred to the transfer chamber 123 by the robot arm 124, and the gate valve 137 is closed. After that, the substrate may be transferred to the heating chamber 130, and the substrate may be heated by the stage 133 having a means for heating the substrate to dry the residual moisture on the substrate. Then, open the gate valve 136,
The substrate is transferred to the chamber 126 for irradiating the laser beam by the robot arm 124, and the gate valve 136 is closed.

A laser beam having a linear shape is used.
The substrate stage 127 is arranged in the width direction of the linear laser beam.
Is moved to irradiate a laser beam onto a predetermined area. Here, in the state of FIG. 7E, the substrate stage 127 is moved so that the laser beam is swept from the right end to the left end of the drawing, and the laser beam is irradiated. The moving speed of the substrate stage 127 here is 1 mm / sec.

After the irradiation of the laser beam is completed, the gate valve 136 is opened, the substrate is transferred to the transfer chamber 123 by the robot arm 124, and the gate valve 136 is closed. Then, the gate valve 135 is opened, and the robot arm 124
The substrate held by is transferred to the oxide film removal chamber 128, and the gate valve 135 is closed.

In the oxide film removing chamber 128, the oxygen concentration of the substrate is set to 2
With the nitrogen atmosphere kept at 0 ppm or less, hydrofluoric acid treatment is performed again to remove the silicon oxide film and expose the crystalline silicon film 157 as shown in FIG. 7F. After that, the gate valve 135 is opened, the substrate is transferred to the transfer chamber 123 by the robot arm 124, and the gate valve 135 is closed. After that, the substrate may be transferred to the heating chamber 130, and the substrate may be heated by the stage 133 having a means for heating the substrate to dry the residual moisture on the substrate. Then, the gate valve 136 is opened, the substrate is transferred by the robot arm 124 to the chamber 126 for irradiating the laser beam, and the gate valve 136 is closed.

In the laser chamber 126, in the state of FIG. 7G, the substrate stage 127 is moved so that the laser beam is swept from the right end to the left end of the drawing, and the laser beam is irradiated. The moving speed of the substrate stage 127 here is 1 mm / sec.

After the irradiation of the laser beam is completed, the gate valve 136 is opened, the substrate is transferred to the transfer chamber 123 by the robot arm 124, and the gate valve 136 is closed. Then, the gate valve 134 is opened to load / unload the substrate 12
The cassette 122 in 1 is closed, and the gate valve 134 is closed.

By repeating the above operation, hydrofluoric acid treatment, oxidation treatment, laser beam irradiation, hydrofluoric acid treatment, and laser beam irradiation are performed on all of the plurality of substrates stored in the cassette 122 in the loading / unloading chamber 121. It can be performed. After completion of hydrofluoric acid treatment, oxidation treatment, laser beam irradiation, hydrofluoric acid treatment and laser beam irradiation on all the substrates, the substrates stored in the cassette 122 are transferred from the substrate loading / unloading chamber 121 of each cassette to the outside of the apparatus. Take it out.

The silicon film thus manufactured is used as a TFT.
If the active layer is used, the variation in the electrical characteristics of the TFT is reduced and the characteristics are improved. [Embodiment 8] In this embodiment, a method for manufacturing an active matrix substrate will be described with reference to FIGS. In this specification, a CMOS circuit, a driving circuit, a pixel TFT,
A substrate in which a pixel portion having a storage capacitor is formed over the same substrate is referred to as an active matrix substrate for convenience.

As shown in FIG. 8A, in this embodiment, a substrate 350 made of glass such as barium borosilicate glass typified by Corning # 7059 glass or # 1737 glass or aluminoborosilicate glass is used. . Note that as the substrate 350, a quartz substrate, a silicon substrate, a metal substrate, or a stainless substrate on which an insulating film is formed may be used. Alternatively, a plastic substrate having heat resistance that can withstand the processing temperature of this embodiment may be used.

Next, a base film 351 made of an insulating film such as a silicon oxide film, a silicon nitride film or a silicon oxynitride film is formed on the substrate 350. Although a two-layer structure is used as the base film 351 in this embodiment, a single layer film of the insulating film or a structure in which two or more layers are stacked may be used. As the first layer of the base film 351, the plasma CVD method is used, and SiH ₄ , N
A silicon oxynitride film 351a formed by using H ₃ and N ₂ O as reaction gases has a thickness of 10 to 200 nm (preferably 50 to 1).
00 nm). In this embodiment, a silicon oxynitride film 351a (composition ratio Si = 32%, O = 27) having a film thickness of 50 nm is used.
%, N = 24%, H = 17%). Next, as the second layer of the base film 351, a silicon oxynitride film 351b formed with SiH ₄ and N ₂ O as a reaction gas is formed to a thickness of 50 to 200 nm (preferably 100 to 150 nm) by a plasma CVD method. Laminated to a thickness. In this embodiment, a 100-nm-thick silicon oxynitride film 351b (composition ratio Si = 32%, O = 59%, N = 7%, H = 2%) is formed.

Next, a semiconductor film 352 is formed on the base film. The semiconductor film 352 is a semiconductor film having an amorphous structure and has a thickness of 25 to 80 nm (preferably 3) by a known means (a sputtering method, an LPCVD method, a plasma CVD method, or the like).
A film having a thickness of 0 to 60 nm) is formed. The semiconductor film 352
Examples thereof include an amorphous semiconductor film, a microcrystalline semiconductor film, and a crystalline semiconductor film. In this embodiment, a plasma CVD method is used to form an amorphous silicon film having a thickness of 55 nm.

Subsequently, a trace amount of an element such as nickel, palladium, or lead is introduced into the amorphous semiconductor film. The method of introduction is plasma treatment, vapor deposition, ion implantation, sputtering,
Solution application or the like may be used. After the introduction, for example, 5
When the amorphous semiconductor is placed in a nitrogen atmosphere at 50 ° C. for 4 hours,
A crystalline semiconductor film having good characteristics can be obtained. The optimum heating temperature, heating time, and the like for crystallization depend on the amount of the element introduced and the state of the amorphous semiconductor film. In this embodiment, a solution containing nickel is held on an amorphous silicon film, the amorphous silicon film is dehydrogenated (500 ° C., 1 hour), and then thermally crystallized (550 ° C., 4 ° C.). Time) to form a crystalline silicon film.

Further, the crystalline semiconductor film obtained by the laser crystallization method to which the laser annealing pretreatment method and the laser annealing treatment method of the present invention are applied is patterned into a desired shape to form semiconductor layers 402 to 406. .

In the laser crystallization method, a pulse oscillation type or continuous oscillation type excimer laser, YAG laser, YV
O ₄ laser, YLF laser, YAlO ₃ laser, glass laser, ruby laser, Ti: sapphire laser, etc. can be used. In the case of using these lasers, it is preferable to use a method in which a laser beam emitted from a laser oscillator is linearly condensed by an optical system and is applied to a semiconductor film. The crystallization conditions are appropriately selected by the practitioner, but when an excimer laser is used, the pulse oscillation frequency is 300 Hz and the laser energy density is 100 to 700 mJ / c.
m ² (typically 200 to 300 mJ / cm ² ). When a YAG laser is used, its second harmonic is used, the pulse oscillation frequency is set to 1 to 300 Hz, and the laser energy density is set to 300 to 1000 mJ / cm ² (typically 350 to 500 mJ / cm ² ). Then, a laser beam converged in a linear shape with a width of 100 to 1000 μm, for example, 400 μm is irradiated over the entire surface of the substrate, and the overlapping ratio (overlap ratio) of the linear beams at this time is 50 to 9
It may be performed as 8%.

In this example, a hydrofluoric acid treatment (etching treatment) was performed as a pretreatment for laser annealing in the same manner as in Example 1, and a natural oxide film and a localized metal film whose composition and film thickness were not controlled were used. The element is removed, and thereafter, an oxidation treatment with ozone water having an ozone concentration of 6 to 15 mg / l is carried out by spin coating at 500 rpm for about 20 to 40 seconds to form a silicon oxide film of about 10 to 20 Å. After that, laser annealing is performed by irradiating a laser beam in a nitrogen atmosphere using a XeCl excimer laser (wavelength 308 nm, pulse width 30 ns) L3308 manufactured by Lambda Corporation in the same manner as in Example 1. This laser oscillator emits a pulsed laser and has an ability to generate energy of 500 mJ / pulse. The size of the laser beam is 10 × 30 mm at the exit of the laser beam (both full width at half maximum in the beam profile). Xe
Using a Cl excimer laser, a laser beam is processed into a linear beam through an optical system as shown in FIG. 3, and laser annealing is performed. Then, the crystalline silicon film is subjected to a patterning process using a photolithography method to form the semiconductor layer 402.
To 406 are formed.

After forming the semiconductor layers 402 to 406, a slight amount of impurity element (boron or phosphorus) may be doped in order to control the threshold value of the TFT.

Next, a gate insulating film 407 which covers the semiconductor layers 402 to 406 is formed. The gate insulating film 407 is formed by a plasma CVD method or a sputtering method and has a thickness of 40 to
It is formed of an insulating film containing silicon with a thickness of 150 nm. In this embodiment, a silicon oxynitride film (composition ratio Si = 32%, O = 59%, N =) having a thickness of 110 nm is formed by the plasma CVD method.
7%, H = 2%). Of course, the gate insulating film is not limited to the silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a laminated structure.

When a silicon oxide film is used, TEOS (Tetraethyl Orthosilicate) is formed by the plasma CVD method.
And O ₂ are mixed, reaction pressure 40 Pa, substrate temperature 300
It can be formed by discharging at a high frequency (13.56 MHz) power density of 0.5 to 0.8 W / cm ² at a temperature of ˜400 ° C. The silicon oxide film thus manufactured can be provided with excellent characteristics as a gate insulating film by subsequent thermal annealing at 400 to 500 ° C.

Then, a film having a thickness of 20 is formed on the gate insulating film 407.
A first conductive film 408 having a thickness of 100 nm and a thickness of 100 to 4
A second conductive film 409 having a thickness of 00 nm is formed by stacking (FIG. 8).
(B)). In this embodiment, a first conductive film 408 made of a TaN film having a film thickness of 30 nm and a second conductive film 409 made of a W film having a film thickness of 370 nm are laminated. The TaN film was formed by a sputtering method and was sputtered in a nitrogen-containing atmosphere using a Ta target. The W film was formed by the sputtering method using a W target. Alternatively, it can be formed by a thermal CVD method using tungsten hexafluoride (WF ₆ ). In any case, it is necessary to reduce the resistance in order to use it as the gate electrode, and it is desirable that the resistivity of the W film be 20 μΩcm or less. Although the W film can be made low in resistivity by enlarging the crystal grains,
When the W film contains many impurity elements such as oxygen, crystallization is hindered and resistance is increased. Therefore, in the present embodiment, the W film is formed by the sputtering method using a high-purity W (purity 99.9999%) target, and with careful consideration that impurities are not mixed from the gas phase during film formation. By forming
A resistivity of 9 to 20 μΩcm could be realized.

Note that in this embodiment, the first conductive film 408 is used.
Is TaN and the second conductive film 409 is W, but is not particularly limited, and Ta, W, Ti, Mo, Al, Cu,
It may be formed of an element selected from Cr or Nd, or an alloy material or a compound material containing the above element as a main component.
Alternatively, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus may be used. Also, AgP
You may use dCu alloy. In addition, the first conductive film is formed of a tantalum (Ta) film, the second conductive film is formed of a W film, and the first conductive film is formed of a titanium nitride (TiN) film. Is a W film, the first conductive film is a tantalum nitride (TaN) film, the second conductive film is an Al film, and the first conductive film is a tantalum nitride (TaN) film. The second conductive film may be a combination of Cu films.

Next, masks 410 to 415 made of resist are formed by photolithography, and a first etching process for forming electrodes and wirings is performed.
The first etching process is performed under the first and second etching conditions. (FIG. 8C) In this embodiment, as the first etching condition, ICP (Inductively Coupled Plasm) is used.
a: inductively coupled plasma etching method, CF ₄ , Cl ₂ and O ₂ are used as etching gases, and the flow rate ratio of each gas is set to 25/25/10 (sccm).
RF of 500 W (13.5
(6 MHz) power was applied to generate plasma for etching. Here, ICP manufactured by Matsushita Electric Industrial Co., Ltd.
Dry etching system (Model E645- □
ICP) was used. 150 on the substrate side (sample stage)
RF (13.56 MHz) power of W is applied and a substantially negative self-bias voltage is applied. The W film is etched under the first etching condition so that the end portion of the first conductive layer is tapered.

After that, the masks 410 to 410 made of resist are formed.
Without removing 415, the second etching condition is changed, CF ₄ and Cl ₂ are used as etching gases, and the gas flow rate ratio of each gas is set to 30/30 (sccm) to form a coil type electrode at a pressure of 1 Pa. An RF (13.56 MHz) power of 500 W was applied to generate plasma and etching was performed for about 30 seconds. 20W R on the substrate side (sample stage)
F (13.56 MHz) power is applied and a substantially negative self-bias voltage is applied. Under the second etching condition in which CF ₄ and Cl ₂ are mixed, the W film and the TaN film are etched to the same extent. Note that in order to perform etching without leaving a residue on the gate insulating film, the etching time may be increased at a rate of about 10 to 20%.

In the first etching process, the shape of the mask made of resist is adjusted to
The edges of the first conductive layer and the second conductive layer are tapered due to the effect of the bias voltage applied to the substrate side. The angle of this tapered portion is 15 to 45 °. Thus, the first shape conductive layers 417 to 422 (first conductive layers 417a to 422a and second conductive layers 417b to 42) including the first conductive layer and the second conductive layer are formed by the first etching treatment.
2b) is formed. 416 is a gate insulating film,
The area not covered with the conductive layers 417 to 422 in the shape of 20 is 20
A thinned region is formed by etching about 50 nm.

Then, a second etching process is performed without removing the resist mask. (FIG. 8 (D)) Here, the W film is selectively etched by using CF ₄ , Cl _2, and O _{2 as} etching gas. At this time, the second conductive layers 428b to 433b are formed by the second etching treatment. On the other hand, the first conductive layers 417a to 422a are
Almost no etching is performed (428a to 433a), and the second shape conductive layers 428 to 433 are formed.

Then, the first doping process is performed without removing the resist mask, and the impurity element imparting n-type is added to the semiconductor layer at a low concentration. The doping treatment may be performed by an ion doping method or an ion implantation method. The condition of the ion doping method is that the dose amount is 1 × 10 ^{13 to} 5
The acceleration voltage is set to × 10 ¹⁴ / cm ² and the acceleration voltage is set to 40 to 80 keV. In this embodiment, the dose amount is 1.5 × 10 ¹³ /
cm ² and accelerating voltage of 60 keV. An element belonging to Group 15 is used as the impurity element imparting n-type, typically phosphorus (P) or arsenic (As), but phosphorus (P) is used here. In this case, the conductive layers 428-4
33 serves as a mask for the impurity element imparting n-type, and the impurity regions 423 to 427 are formed in a self-aligned manner. The impurity regions 423 to 427 have 1 × 10 ¹⁸ to 1 × 1.
An impurity element imparting n-type is added within a concentration range of 0 ²⁰ / cm ³ . After removing the masks made of resist, new masks 434a to 434c made of resist are formed, and the second doping process is performed at an acceleration voltage higher than that of the first doping process. The condition of the ion doping method is that the dose amount is 1 × 10 ¹³ to 1 × 10 ¹⁵ / cm ² and the acceleration voltage is 60 to 120 keV. In the doping process, the second conductive layers 428b to 432b are used as a mask for the impurity element, and doping is performed so that the semiconductor layer below the tapered portion of the first conductive layer is added with the impurity element. Subsequently, the acceleration voltage is lowered from the second doping process and the third doping process is performed to obtain the state of FIG. The condition of the ion doping method is that the dose amount is 1 × 10 ¹⁵ to
1 × 10 ¹⁷ / cm ² and accelerating voltage of 50 to 100 ke
Perform as V. By the second doping treatment and the third doping treatment, 1 × 10 ^{18 to} 5 × 1 are formed in the low-concentration impurity regions 436, 442, and 448 overlapping with the first conductive layer.
An impurity element imparting n-type conductivity is added in a concentration range of 0 ¹⁹ / cm ³ , and high concentration impurity regions 435, 438, 441,
Impurity elements imparting n-type are added to 444 and 447 in a concentration range of 1 × 10 ^{19 to} 5 × 10 ²¹ / cm ³ .

Of course, by selecting an appropriate acceleration voltage,
The low-concentration impurity region and the high-concentration impurity region formed by the second doping treatment and the third doping treatment,
It is also possible to perform the doping process once.

Next, after removing the resist masks, new resist masks 450a to 450a are formed.
c is formed and a fourth doping process is performed. This 4th
Impurity regions 451 and 453 in which an impurity element that imparts a conductivity type opposite to the one conductivity type is added to the semiconductor layer that becomes the active layer of the p-channel TFT by the doping process.
455, 457, 459 and 460 are formed. The second conductive layers 428a to 432a are used as masks for the impurity element, the impurity element imparting p-type conductivity is added, and the impurity regions are formed in a self-aligned manner. In this embodiment, the impurity regions 451, 453 to 455 to 455, 457, 459 and 460 are formed by an ion doping method using diborane (B ₂ H ₆ ). (FIG. 9B) At the time of the fourth doping process, the semiconductor layer forming the n-channel TFT is partially covered with masks 450a to 450c made of resist. Although phosphorus is added to the impurity regions 438 and 439 at different concentrations by the first to third doping processes, the concentration of the impurity element imparting p-type conductivity is set to 1 × 10 ^{19 to} 5 in any of the regions. × 10 ²¹ atom
By performing the doping treatment so that the s / cm ³ is obtained, there is no problem because it functions as the source region and the drain region of the p-channel TFT.

Through the above steps, the impurity regions are formed in the respective semiconductor layers.

Next, a mask 450a made of resist.
To 450c are removed to form a first interlayer insulating film 461. As the first interlayer insulating film 461, plasma C is used.
The thickness is 100 to 200 using the VD method or the sputtering method.
It is formed of an insulating film containing silicon as nm. In this embodiment, a silicon oxynitride film having a thickness of 150 nm is formed by a plasma CVD method. Of course, the first interlayer insulating film 461 is not limited to the silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a laminated structure.

Next, as shown in FIG. 9C, heat treatment is performed to recover the crystallinity of the semiconductor layers and activate the impurity elements added to the respective semiconductor layers. This heat treatment is performed by a thermal annealing method using a furnace annealing furnace. As a thermal annealing method, oxygen concentration is 1 ppm
4 or less, preferably 0.1 ppm or less in a nitrogen atmosphere
The activation treatment may be performed at a temperature of 00 to 700 ° C., typically 500 to 550 ° C. In this embodiment, the heat treatment is performed at 550 ° C. for 4 hours. In addition to the thermal annealing method, a laser annealing method or a rapid thermal annealing method (RTA
Law) can be applied.

In the present embodiment, at the same time as the activation treatment, the impurity regions 435, 438, 441, 4 used as a catalyst during crystallization and containing nickel at a high concentration were used as a catalyst.
Crystallize 44, 447. Therefore, the metal element in the impurity region is gettered, and the concentration of nickel in the semiconductor layer mainly serving as the channel formation region is reduced. A TFT having a channel formation region manufactured in this manner has a low off-state current value and high crystallinity, whereby high field-effect mobility can be obtained and favorable characteristics can be achieved.

Further, heat treatment may be performed before forming the first interlayer insulating film. However, when the wiring material used is weak against heat, activation is performed after forming an interlayer insulating film (insulating film containing silicon as a main component, for example, a silicon nitride film) to protect the wiring and the like as in this embodiment. It is preferable to carry out a chemical treatment.

Then, heat treatment (1 at 300 to 550 ° C.)
Hydrogenation can be performed by performing a heat treatment for 12 hours. This step is a step of terminating the dangling bond of the semiconductor layer with hydrogen contained in the first interlayer insulating film 461. The semiconductor layer can be hydrogenated regardless of the presence of the first interlayer insulating film. As another means of hydrogenation,
Plasma hydrogenation (using hydrogen excited by plasma) or 300 to 300% in an atmosphere containing 3 to 100% hydrogen
You may heat-process at 450 degreeC for 1 to 12 hours.

When the laser annealing method is used as the activation process, it is desirable to irradiate a laser beam such as an excimer laser or a YAG laser after performing the above hydrogenation.

Next, a second interlayer insulating film 462 made of an inorganic insulating film material or an organic insulating material is formed on the first interlayer insulating film 461. In this embodiment, the film thickness is 1.6 μm
The acrylic resin film of
cp, preferably 40 to 200 cp is used. Alternatively, a film having a flat surface may be used as the second interlayer insulating film 462.

Then, in the drive circuit 506, wirings 463 to 467 electrically connected to the respective impurity regions.
To form. Note that these wirings have a thickness of 50 nm.
A laminated film of an i film and an alloy film (alloy film of Al and Ti) having a film thickness of 500 nm is formed by patterning. (Fig. 1
0) Further, in the pixel portion 507, the pixel electrode 470,
A gate wiring 469 and a connection electrode 468 are formed. By this connection electrode 468, the source wiring (a stack of 443a and 443b) is electrically connected to the pixel TFT 504. The gate wiring 469 is electrically connected to the gate electrode of the pixel TFT. In addition, the pixel electrode 470
Are electrically connected to the drain region of the pixel TFT, and further electrically connected to the semiconductor layer 406 which functions as one electrode forming a storage capacitor. Also,
As the pixel electrode 470, it is desirable to use a material having excellent reflectivity such as a film containing Al or Ag as a main component, or a laminated film thereof. The pixel electrode 470 is I
A transparent conductive film such as TO can be used.

As described above, the n-channel TFT 50
1 and a p-channel TFT 502 CMOS circuit 5
The driver circuit 506 including the 08 and the n-channel TFT 503, and the pixel portion 507 including the pixel TFT 504 and the storage capacitor 505 can be formed over the same substrate.
Thus, the active matrix substrate is completed.

N-channel TFT 50 of drive circuit 506
Reference numeral 1 denotes a channel formation region 437, and a low-concentration impurity region 4 overlapping with the first conductive layer 428a forming part of the gate electrode.
36 (GOLD region), a high-concentration impurity region 452 functioning as a source region or a drain region, and an impurity region 451 in which an impurity element imparting n-type and an impurity element imparting p-type are introduced. The n-channel TFT 501 is connected to the electrode 466 to connect to the CMOS circuit 5.
A channel formation region 440, a high-concentration impurity region 454 functioning as a source region or a drain region, an impurity element imparting n-type conductivity, and an impurity element imparting p-type conductivity are introduced into the p-channel TFT 502 forming 08. It has regions 453 and 454. Further, in the n-channel TFT 503, a channel forming region 443, a low concentration impurity region 442 (GOLD region) overlapping with the first conductive layer 430a forming a part of a gate electrode, and a high concentration impurity functioning as a source region or a drain region. It has a region 456 and an impurity region 455 into which an impurity element imparting n-type conductivity and an impurity element imparting p-type conductivity are introduced.

In the pixel TFT 504 of the pixel portion, a channel forming region 446, a low concentration impurity region 445 (LDD region) formed outside the gate electrode, a high concentration impurity region 458 functioning as a source region or a drain region, and n are formed.
It has an impurity region 457 into which an impurity element imparting a type and an impurity element imparting a p-type are introduced. Also,
An impurity element imparting n-type conductivity and an impurity element imparting p-type conductivity are added to the semiconductor layer functioning as one electrode of the storage capacitor 505. The storage capacitor 505 is formed of an electrode (a stack of 432a and 432b) and a semiconductor layer using the insulating film 416 as a dielectric. In the pixel structure of the present embodiment, the end portion of the pixel electrode is arranged and formed so as to overlap the source wiring so that the gap between the pixel electrodes is shielded without using the black matrix.

FIG. 11 is a top view of the pixel portion of the active matrix substrate manufactured in this example. The same reference numerals are used for the portions corresponding to FIGS.
The chain line AA ′ in FIG. 10 corresponds to the cross-sectional view taken along the chain line AA ′ in FIG. 11. Also, a chain line B in FIG.
-B 'corresponds to the cross-sectional view taken along the chain line BB' in FIG.

It should be noted that this embodiment can be freely combined with any one of Embodiments 1 to 4 and Embodiments 6 to 7. [Embodiment 9] In this embodiment, a process of manufacturing a reflective liquid crystal display device from the active matrix substrate manufactured in Embodiment 8 will be described below. FIG. 12 is used for the description.

First, according to the eighth embodiment, after obtaining the active matrix substrate in the state of FIG. 10, an alignment film 567 is formed on at least the pixel electrode 470 on the active matrix substrate of FIG. 10 and rubbing treatment is performed. In this embodiment, before forming the alignment film 567, the organic resin film such as the acrylic resin film is patterned to form the columnar spacers 572 for holding the substrate distance at desired positions. Further, spherical spacers may be dispersed over the entire surface of the substrate instead of the columnar spacers.

Next, a counter substrate 569 is prepared. Next, the coloring layers 570 and 571 and the planarization film 573 are formed over the counter substrate 569. The red colored layer and the blue colored layer are overlapped to form a light shielding part. In addition, the light-shielding portion may be formed by partially overlapping the red colored layer and the green colored layer.

In this example, the substrate shown in Example 8 is used. Therefore, FIG. 1 showing a top view of the pixel portion of the eighth embodiment.
1, at least the gate wiring 469 and the pixel electrode 470.
It is necessary to shield light from the gap between the gate wiring 469 and the connection electrode 468, and the gap between the connection electrode 468 and the pixel electrode 470. In this example, the colored layers were arranged so that the light-shielding portions formed by stacking the colored layers were overlapped with each other at the positions where they should be shielded, and the counter substrates were bonded together.

As described above, the number of steps can be reduced by forming a light-shielding portion formed of a stack of colored layers so as to shield the gaps between pixels without forming a light-shielding layer such as a black mask.

Next, a counter electrode 576 made of a transparent conductive film was formed on the flattening film 573 at least in the pixel portion, an alignment film 574 was formed on the entire surface of the counter substrate, and a rubbing treatment was performed.

Then, a sealing material 568 is formed between the active matrix substrate on which the pixel portion and the driving circuit are formed and the counter substrate.
Stick together. A filler is mixed in the sealing material 568, and the two substrates are bonded to each other with a uniform interval by the filler and the columnar spacers. afterwards,
A liquid crystal material 575 is injected between both substrates and completely sealed with a sealant (not shown). A known liquid crystal material may be used as the liquid crystal material 575. In this way, the reflection type liquid crystal display device shown in FIG. 12 is completed. When a transparent conductive film is used for the pixel electrode, a transmissive liquid crystal display device can be manufactured. Then, if necessary, the active matrix substrate or the counter substrate is cut into a desired shape. Further, a polarizing plate (not shown) was attached only to the counter substrate. Then, the FPC was attached using a known technique.

Further, this embodiment can be freely combined with any one of Embodiments 1 to 4 and Embodiments 6 to 8. The liquid crystal display panel manufactured as described above can be used for various electric appliances. It can be used as a display unit. [Embodiment 10] Various electro-optical devices (also referred to as active matrix type liquid crystal displays) for CMOS circuits and pixel portions formed by implementing the present invention by applying the present invention.
Can be used for. That is, the present invention can be applied to all electric appliances in which the electro-optical device is incorporated in the display section.

Examples of such electric appliances include video cameras, digital cameras, projectors, head mounted displays (goggles type displays), car navigations, car stereos, personal computers, personal digital assistants (mobile computers, mobile phones, electronic books, etc.). ) And the like. Examples of those are shown in FIG.
This is shown in FIGS. 14 and 15.

FIG. 13A shows a personal computer, which has a main body 3001, an image input section 3002, and a display section 30.
03, keyboard 3004 and the like. Display unit 3 of the present invention
003 can be applied.

FIG. 13B shows a video camera, which includes a main body 3101, a display portion 3102, a voice input portion 3103, operation switches 3104, a battery 3105, and an image receiving portion 310.
Including 6 etc. The present invention can be applied to the display portion 3102.

FIG. 13C shows a mobile computer (mobile computer), which includes a main body 3201, a camera portion 3202, an image receiving portion 3203, operation switches 3204, a display portion 3205, and the like. The present invention can be applied to the display portion 3205.

FIG. 13D shows a goggle type display, which includes a main body 3301, a display portion 3302 and an arm portion 330.
Including 3 etc. The present invention can be applied to the display portion 3302.

FIG. 13E shows a player using a recording medium (hereinafter, referred to as a recording medium) in which a program is recorded, which is a main body 3401, a display portion 3402, a speaker portion 340.
3, a recording medium 3404, operation switches 3405 and the like. This player uses a DVD (D
optical Versatile Disc), CD
You can enjoy listening to music, watching movies, playing games, and using the Internet. The present invention can be applied to the display portion 3402.

FIG. 13F shows a digital camera, which includes a main body 3501, a display portion 3502, an eyepiece portion 3503, operation switches 3504, an image receiving portion (not shown) and the like. The present invention can be applied to the display portion 3502.

FIG. 14A shows a front type projector including a projection device 3601, a screen 3602 and the like. The present invention can be applied to the liquid crystal display device 3808 which constitutes a part of the projection device 3601 and other drive circuits.

FIG. 14B shows a rear type projector, which includes a main body 3701, a projection device 3702, and a mirror 370.
3, screen 3704 and the like. The present invention is a projection device 2
The invention can be applied to the liquid crystal display device 3808 which forms a part of 702 and other driver circuits.

Note that FIG. 14C is a diagram showing an example of the structure of the projection devices 3601 and 3702 in FIGS. 14A and 14B. Projection devices 3601, 37
02 is a light source optical system 3801, mirrors 3802, 380
4 to 3806, dichroic mirror 3803, prism 3807, liquid crystal display device 3808, retardation plate 380.
9, a projection optical system 3810. Projection optical system 38
Reference numeral 10 is composed of an optical system including a projection lens. Although the present embodiment shows an example of a three-plate type, it is not particularly limited and may be, for example, a single-plate type. In addition, the practitioner may appropriately provide an optical system such as an optical lens, a film having a polarization function, a film for adjusting a phase difference, and an IR film in the optical path indicated by an arrow in FIG. 14C. Good.

Further, FIG. 14D is a diagram showing an example of the structure of the light source optical system 3801 in FIG. 14C. In this embodiment, the light source optical system 3801 includes a reflector 2811, a light source 3812, a lens array 3813, and a lens array 3813.
814, a polarization conversion element 2815, and a condenser lens 3816. The light source optical system shown in FIG. 14D is an example and is not particularly limited. For example, the practitioner may appropriately provide an optical system such as an optical lens, a film having a polarization function, a film for adjusting a phase difference, and an IR film in the light source optical system.

However, the projector shown in FIG. 14 shows a case where a transmissive electro-optical device is used, and an application example in a reflective electro-optical device and a light emitting device is not shown.

FIG. 15A shows a mobile phone, which is a main body 39.
01, voice output unit 3902, voice input unit 3903, display unit 3904, operation switch 3905, antenna 3906
Including etc. The present invention can be applied to the display portion 3904.

FIG. 15B shows a portable book (electronic book) including a main body 4001, display portions 4002 and 4003, a storage medium 4004, operation switches 4005, an antenna 4006.
Including etc. The present invention can be applied to the display portions 4002 and 4003.

FIG. 15C shows a display, which includes a main body 4101, a support base 4102, a display portion 4103, and the like.
The present invention can be applied to the display portion 4103. The display of the present invention is particularly advantageous when it has a large screen, and is advantageous for a display having a diagonal of 10 inches or more (particularly 30 inches or more).

As described above, the applicable range of the present invention is extremely wide, and the present invention can be applied to electric appliances of various fields. In addition, the electric device of the present embodiment can be realized by using a configuration including any combination of Embodiments 1 to 4 and Embodiments 6 to 10.

[0199]

By adopting the structure of the present invention,
The following basic significance can be obtained. (a) TFT based on the crystalline semiconductor film obtained by the present invention
When the above is manufactured, variations in electrical characteristics of the TFT are reduced. (b) TFT based on the crystalline semiconductor film obtained by the present invention
Is produced, the electrical characteristics of the TFT are improved. (c) By using the laser processing apparatus of the present invention, it is possible to minimize a decrease in productivity and throughput.

[Brief description of drawings]

FIG. 1A is a process chart of the present invention, and FIG. 1B is a diagram showing dependence of TFT characteristics of the present invention on pretreatment by laser annealing.

FIG. 2 is a cross-sectional view showing a manufacturing process of the first embodiment and the first to third examples.

3A and 3B are a top view and a cross-sectional view of an optical system for processing a laser beam of the present invention into a linear beam.

4A to 4C are cross-sectional views showing a manufacturing process of Embodiment Mode 2 and Embodiment Example 4;

FIG. 5 shows an example of a laser processing apparatus of the present invention.

6A to 6C are cross-sectional views showing a manufacturing process of a sixth embodiment.

FIG. 7 is a cross-sectional view showing the manufacturing process of the seventh embodiment.

8A to 8C are cross-sectional views illustrating a manufacturing process of a pixel TFT and a driver circuit TFT of Example 8.

9A to 9C are cross-sectional views showing a manufacturing process of a pixel TFT and a driver circuit TFT of Example 8. FIGS.

FIG. 10: Pixel TFT of Example 8, TFT of drive circuit
6A to 6D are cross-sectional views showing a manufacturing process of.

FIG. 11 is a top view showing a pixel of a pixel portion of Example 8.

12A and 12B are cross-sectional views showing a manufacturing process of an active matrix liquid crystal display device of Example 9.

FIG. 13 is a diagram showing an example of an electric device according to a tenth embodiment.

FIG. 14 is a diagram showing an example of an electric device according to a tenth embodiment.

FIG. 15 is a diagram showing an example of an electric device according to a tenth embodiment.

FIG. 16 shows the EBSP evaluation results of the semiconductor film of the present invention.

FIG. 17 is an EBSP evaluation result of a conventional LPS film.

FIG. 18 is an SEM observation result of the semiconductor film of the present invention.

FIG. 19 shows the relationship between the S value and the domain size of the present invention.

FIG. 20 shows the relationship between mobility and domain size according to the present invention.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Naoki Makita             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Takuya Matsuo             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company F-term (reference) 5F052 AA02 AA11 AA17 BA01 BA07                       BA18 BB01 BB02 BB04 BB05                       BB07 DA01 DA02 DA03 DB02                       DB03 DB07 EA01 FA06 FA19                       JA01                 5F110 AA17 BB02 BB04 CC02 DD01                       DD02 DD03 DD05 DD13 DD14                       DD15 DD17 EE01 EE02 EE03                       EE04 EE06 EE14 EE23 EE28                       EE44 EE45 FF02 FF04 FF09                       FF12 FF28 FF30 GG02 GG13                       GG25 GG32 GG43 GG45 GG47                       HJ01 HJ04 HJ12 HJ13 HJ23                       HL04 HL06 HL11 HM15 NN03                       NN04 NN22 NN27 NN34 NN35                       NN72 NN73 PP01 PP03 PP04                       PP05 PP06 PP10 PP13 PP29                       PP31 PP34 QQ04 QQ09 QQ23                       QQ24 QQ25 QQ28

Claims (27)

[Claims] 1. A first step of introducing a metal element into an amorphous semiconductor film formed on a substrate, and a heat treatment of the amorphous semiconductor film to form a first crystalline semiconductor film. Step 2, a third step of removing the oxide film formed on the surface of the first crystalline semiconductor film, and a clean oxidation by applying an oxidation treatment having an organic substance removing effect to the first crystalline semiconductor film. A fourth step of forming a film; and a fifth step of forming a second crystalline semiconductor film by irradiating the first crystalline semiconductor film with a laser beam in an inert atmosphere.
And a step of manufacturing a semiconductor device. 2. A first step of introducing a metal element into an amorphous semiconductor film formed on a substrate, and a heat treatment of the amorphous semiconductor film to form a first crystalline semiconductor film. Step 2, a third step of removing the oxide film formed on the surface of the first crystalline semiconductor film, and a clean oxidation by applying an oxidation treatment having an organic substance removing effect to the first crystalline semiconductor film. A fourth step of forming a film, and a fifth step of forming a second crystalline semiconductor film by irradiating the first crystalline semiconductor film with a laser beam in an inert gas atmosphere having an oxygen concentration of 20 ppm or less. A method for manufacturing a semiconductor device, comprising: 3. A first step of introducing a metal element into an amorphous semiconductor film formed on a substrate, and a heat treatment of the amorphous semiconductor film to form a first crystalline semiconductor film. Step 2, a third step of removing the oxide film formed on the surface of the first crystalline semiconductor film, and a clean oxidation by applying an oxidation treatment having an organic substance removing effect to the first crystalline semiconductor film. A fourth step of forming a film, and a fifth step of forming a second crystalline semiconductor film by irradiating the first crystalline semiconductor film with a laser beam in an inert gas atmosphere having an oxygen concentration of 20 ppm or less. A sixth step of removing an oxide film formed on the surface of the second crystalline semiconductor film, and a laser beam in the second crystalline semiconductor film in an inert gas atmosphere having an oxygen concentration of 20 ppm or less. And a seventh step of irradiating Manufacturing method of semiconductor device. 4. The method according to any one of claims 1 to 3, wherein the third step is a step of removing an oxide film with hydrofluoric acid, and the fourth step is applying ozone water. A method for manufacturing a semiconductor device, which is a step of forming an oxide film thereby. 5. The method according to any one of claims 1 to 3, wherein the third step is a step of removing an oxide film with hydrofluoric acid, and the fourth step is irradiation with UV light. A method for manufacturing a semiconductor device, which is a step of forming an oxide film thereby. 6. The method according to claim 1, wherein the third step is a step of removing an oxide film with hydrofluoric acid, and the fourth step is applying a sulfuric acid / hydrogen peroxide mixture. A method for manufacturing a semiconductor device, which is a step of forming an oxide film by performing the above. 7. The method for manufacturing a semiconductor device according to claim 1, wherein the inert gas atmosphere is nitrogen, hydrogen, or a rare gas. 8. The metal element according to claim 1, wherein the metal element is Ni, Pd, Pt, Cu or A.
A method of manufacturing a semiconductor device, which is one or more kinds of elements selected from g, Au, Al, In, Sn, or Pd. 9. The metal element according to any one of claims 1 to 3, wherein the metal element is one or more kinds of elements selected from Group 8, Group 11, Group 13, Group 14 or Group 15 elements. A method for manufacturing a semiconductor device, including: 10. The method for manufacturing a semiconductor device according to claim 1, wherein the amorphous semiconductor film is an amorphous silicon film. 11. The method for manufacturing a semiconductor device according to claim 1, wherein the first crystalline semiconductor film is a crystalline silicon film. 12. The method for manufacturing a semiconductor device according to claim 1, wherein the second crystalline semiconductor film is a crystalline silicon film. 13. An oxide film removing chamber for removing an oxide film formed on a surface of a first crystalline semiconductor film formed on a substrate, and an organic material on the surface of the first crystalline semiconductor film is removed for oxidation. A semiconductor manufacturing apparatus comprising: an oxidation treatment chamber for performing a treatment; and a laser treatment chamber for irradiating a laser beam to the first crystalline semiconductor film to form a second crystalline semiconductor film. 14. An oxide film removing chamber for removing an oxide film formed on a surface of a first crystalline semiconductor film formed on a substrate, and an organic material on the surface of the first crystalline semiconductor film is removed for oxidation. An oxidizing treatment chamber having a chemical solution nozzle and a laser treatment chamber for irradiating the first crystalline semiconductor film with a laser beam to form a second crystalline semiconductor film are provided as means for performing the above. Semiconductor manufacturing equipment. 15. An oxide film removing chamber for removing an oxide film formed on a surface of a first crystalline silicon film formed on a substrate, and an organic material on the surface of the first crystalline semiconductor film is removed for oxidation. An oxidation treatment chamber having means for irradiating UV light as a means for irradiating the laser beam; and a laser treatment chamber for irradiating the first crystalline semiconductor film with a laser beam to form a second crystalline semiconductor film. A semiconductor manufacturing apparatus characterized by: 16. An oxide film removing chamber for removing an oxide film formed on a surface of a first crystalline semiconductor film formed on a substrate, and an organic material on the surface of the first crystalline semiconductor film is removed for oxidation. An oxidizing treatment chamber having a chemical solution nozzle as a means for effecting the irradiation, and a laser beam is irradiated to the first crystalline semiconductor film in an inert gas atmosphere having an oxygen concentration of 20 ppm or less to form a second crystalline semiconductor film. A semiconductor manufacturing apparatus comprising: a laser processing chamber; 17. An oxide film removing chamber for removing an oxide film formed on the surface of a first crystalline semiconductor film formed on a substrate, and an organic material for removing an oxide on the surface of the first crystalline semiconductor film for oxidation. An oxidation treatment chamber having a means for irradiating UV light as a means for irradiating the second crystalline semiconductor, and irradiating the first crystalline semiconductor film with a laser beam in an inert gas atmosphere having an oxygen concentration of 20 ppm or less A laser manufacturing chamber for forming a film, and a semiconductor manufacturing apparatus. 18. The semiconductor manufacturing apparatus according to claim 13, further comprising a transfer chamber having a mechanism for transferring a substrate, wherein the oxide film removing chamber, the oxidation processing chamber, and the laser processing chamber are provided. Is a semiconductor manufacturing apparatus, which is connected to a transfer chamber via a gate valve. 19. The semiconductor manufacturing method according to claim 13, wherein the chemical liquid nozzle is a nozzle for injecting ozone water or a mixed liquid of sulfuric acid and hydrogen peroxide. apparatus. 20. The semiconductor manufacturing apparatus according to claim 13, wherein the first crystalline semiconductor film is a crystalline silicon film. 21. The semiconductor device according to any one of claims 13 to 17, wherein the second crystalline semiconductor film is a crystalline silicon film. 22. A polycrystalline semiconductor film is used as an active layer, wherein the active layer includes a high-angle grain boundary and a low-angle grain boundary, and the number of grain boundaries crossed when a current flows through the active layer is equal to the current A semiconductor device having one or more large-angle grain boundaries and one or more small-angle grain boundaries per path length 1 μ, and the small-angle grain boundaries having an orientation deviation of less than 15 ° at the grain boundaries. . 23. A polycrystalline semiconductor film is used as an active layer, wherein the active layer includes a high-angle grain boundary and a low-angle grain boundary, and an average diameter of an aggregate of crystal grains having the low-angle grain boundary is 1 μm or more. Yes, the small tilt angle grain boundary has a misalignment of 15 at the grain boundary.
A semiconductor device characterized by being less than °. 24. The current path length according to claim 22,
A semiconductor device having 0.2 or less large-angle grain boundaries per μm. 25. The semiconductor device according to claim 23, wherein an average diameter of the aggregate of crystal grains is 5 μm or more. 26. The semiconductor device according to any one of claims 22 to 25, wherein the semiconductor device is a liquid crystal display device. 27. The semiconductor device according to claim 22, wherein the semiconductor device is a mobile phone, a video camera, a digital camera, a projector, a goggle type display, a personal computer, or a storage medium storing a program. A semiconductor device, which is a player or an electronic book.