JP2000345343A - Film forming equipment - Google Patents

Abstract

(57) [Problem] To provide a film forming apparatus capable of improving corrosion resistance and extending the life by increasing the surface roughness of members in a processing container. SOLUTION: An object to be processed W is mounted on a mounting table 26 installed in a processing container 22 which can be evacuated, and a film forming process is performed by introducing a film forming gas into the processing container. The component 2 provided in the processing container
The surface roughness of 6, 58, 66 is set to be larger than the surface roughness when this part is used as a standard. As described above, by increasing the surface roughness of the components in the processing container, the corrosion resistance is improved and the life is extended.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a film forming apparatus for performing a film forming process on a semiconductor wafer or the like.

[0002]

2. Description of the Related Art Generally, in the process of manufacturing a semiconductor integrated circuit, W (tungsten) and WSi (tungsten) are used to form a wiring pattern on the surface of a semiconductor wafer to be processed or to bury recesses between wirings. A thin film is formed by depositing a metal or a metal compound such as silicide), Ti (titanium), TiN (titanium nitride), and TiSi (titanium silicide). To form these films, WF ₆ , TiCl
₄ , a highly corrosive gas made of a halogen compound such as SiH ₂ Cl ₂ is used, and a corrosive gas such as HCl is generated depending on the type of gas used.

Further, when a certain number of wafers are subjected to film forming processing in the same film forming apparatus, an unnecessary film which causes particles adheres when peeled off, so that the unnecessary film is removed. Therefore, the cleaning operation is performed regularly or irregularly. This cleaning operation also uses a highly corrosive gas such as a ClF-based gas or an HF-based gas. For example, to form tungsten silicide (WSix) using WF ₆ (tungsten hexafluoride) or SiH ₂ Cl ₂ (dichlorosilane), the process is performed in a high temperature range of about 500 to 600 ° C.
To remove an unnecessary tungsten silicide film, ClF ₃ gas is used as a cleaning gas, and 200 to 25
Cleaning is performed in a temperature range of about 0 ° C. At this time, the unnecessary tungsten silicide film is removed by an exothermic reaction with the ClF ₃ gas.

[0004]

However, as described above, the highly corrosive gas acts on various components in the film forming apparatus, and has a problem that the surface is corroded to shorten the life. . Since the corrosion reaction progresses faster as the temperature of the component is higher, the shortening of the life of the component is accelerated accordingly. This will be described with reference to FIG. FIG. 8 is a schematic configuration diagram showing a conventional general film forming apparatus. This film forming apparatus has a processing container 2 which can be evacuated. A cylindrical reflector 4 is provided in the processing vessel 2.
A mounting table 6 made of, for example, amorphous carbon, which is supported by the semiconductor wafer W, is mounted on the upper surface of the mounting table 6. A transmission window 8 made of, for example, quartz glass is provided at the bottom of the container below the mounting table 6, and further transmits heat rays from a plurality of heating lamps 10 rotatably disposed below the mounting table 6. And semiconductor wafer W
Is to be heated.

A rectifying hole 1 is provided outside the mounting table 6.
For example, a ring-shaped attachment member 14 made of, for example, aluminum or quartz made of aluminum is provided between the container and the inner peripheral wall of the container. A shield ring 16 made of, for example, amorphous carbon is provided so as to bridge between a step on the peripheral edge of the mounting table 6 and a step on the inner peripheral side of the attachment member 14. The effect of this is to deposit a film having a uniform thickness on the wafer surface. Further, a shower head 18 made of, for example, aluminum or nickel is provided on the ceiling of the container facing the mounting table 6 in order to introduce a necessary film forming gas into the processing container 2. In such a film forming apparatus, components mainly in the processing container 2, particularly,
There has been a problem that components exposed to a high temperature state, for example, the surface of the mounting table 6, the shield ring 16 on its outer periphery, the shower head portion 18, and the like are strongly corroded. The present invention has been devised in view of the above problems and effectively solving them. An object of the present invention is to provide a film forming apparatus capable of improving the corrosion resistance and extending the life by increasing the surface roughness of components in a processing container.

[0006]

According to a first aspect of the present invention, an object to be processed is mounted on a mounting table installed in a processing container capable of being evacuated, and a film forming gas is stored in the processing container. In a film forming apparatus that performs a film forming process by introducing
The surface roughness of the component provided in the processing container is set to be larger than the surface roughness when the component is used as a standard. By increasing the surface roughness in this manner, the amount of unnecessary film formed per unit area is reduced, and the amount of heat generated at that portion during cleaning is reduced, or the surface temperature is reduced. Corrosion can be improved. Such a component is, for example, a mounting table, a shield ring, or a shower head as defined in claims 2 to 4.

Further, as set forth in claim 5, the material of the mounting table or the shield ring is AlN, Al ₂ O.
₃ , SiC, SiO ₂ , Si ₃ N _4, and amorphous carbon. Further, when the mounting table or the shield ring is made of amorphous carbon, the surface roughness is set to 3.
It is set within the range of 0 to 10.0 μm. Still further, as set forth in claim 7, the surface of the component is subjected to a plasma etching process. According to this, it is possible to further improve the corrosion resistance.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a film forming apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional configuration diagram showing a film forming apparatus according to the present invention, FIG. 2 is a partially enlarged view showing a mounting table and its peripheral portion in FIG. 1, and FIG.
It is an enlarged view which shows a part. The film forming apparatus 20 has a processing container 22 formed into a cylindrical shape or a box shape from, for example, aluminum or the like. Inside the processing container 22, a cylindrical aluminum product standing from the bottom of the processing container is provided. A mounting table 26 for mounting a semiconductor wafer W as an object to be processed is provided on the reflector 24.

Below the mounting table 26, a plurality of, for example, three (only two in the illustrated example) lifter pins 28 are provided so as to rise upward with respect to the support member 30. The wafer W can be lifted by moving the lifter pin 28 up and down by a push-up rod 32 provided through the bottom of the processing container so that the lifter pin 28 is inserted through a lifter pin hole 34 provided through the mounting table 26. ing. The lower end of the push-up bar 32 is connected to an actuator 38 via a bellows 36 which can be expanded and contracted in order to maintain an airtight state inside the processing container 22.

At the bottom of the processing container just below the mounting table 26, a transmission window 40 made of a heat ray transmitting material such as quartz glass is provided in an airtight manner. A heating chamber 42 is provided. In the heating chamber 42, a plurality of heating lamps 44 as heating means are mounted on a turntable 46 also serving as a reflecting mirror, and the turntable 46 is provided at the bottom of the heating chamber 42 via a rotary shaft. It is rotated by a motor 48. Therefore, the heat rays emitted from the heating lamp 44 can pass through the transmission window 40 and irradiate the lower surface of the mounting table 26 to heat it. Note that, instead of the heating lamp 44 as a heating means, a resistance heater may be provided so as to be embedded in the mounting table 26.

A ring-shaped attachment member 52 made of, for example, aluminum and having a large number of flow regulating holes 50 is provided on the outer peripheral side of the mounting table 26 and supported by a support column 54. The mounting table 26 is made of, for example, a disc-shaped amorphous carbon having a thickness of, for example, about 2 mm, and has a step 56 formed at its peripheral edge by shaving a corner into a ring shape. A ring-shaped stepped portion 59 is also formed on the inner periphery of the attachment member 52 adjacent to the outer periphery. A ring-shaped shield ring 58 is provided so as to be bridged between the step portions 56 and 59, and by this operation, the in-plane uniformity of the thickness of the film deposited on the surface of the wafer W is improved. I am getting it. The material of the shield ring 58 is the same as that of the mounting table 26 described above.
For example, it is made of amorphous carbon. The mounting table 2
6 and the shield ring 58 may be made of AlN, Al ₂ O ₃ , SiC, S
iO ₂ , Si ₃ N _{4 and the} like can also be used.

An exhaust port 60 is provided at a bottom portion below the attachment member 52, and an exhaust path 62 connected to a vacuum pump (not shown) is connected to the exhaust port 60 so that the inside of the processing vessel 22 is connected. A predetermined degree of vacuum can be maintained. A gate valve 64 that is opened and closed when a wafer is loaded and unloaded is provided on a side wall of the processing container 22.

On the other hand, a shower head 66 for introducing a processing gas or the like into the processing container 22 is provided at the processing container ceiling facing the mounting table 26. Specifically, the shower head section 66 has a head body 68 formed into a circular box shape by, for example, aluminum or the like,
A gas inlet 70 is provided in the ceiling. Gases necessary for film formation, such as WF ₆ , SiCl ₂ H ₂ , H ₂ ,
A gas source such as N ₂ or Ar is connected to supply the gas so that the flow rate can be controlled. At the lower part of the head main body 68, a number of gas injection holes 74 for discharging the gas supplied into the head main body 68 to the processing space S are arranged substantially over the entire surface, and over the wafer surface. It is designed to emit gas.

A diffusion plate 78 having a large number of gas dispersion holes 76 is provided in the head main body 68 so as to supply gas more evenly to the wafer surface.
In the present invention, the surface roughness of the component in the processing container 22 is set to be larger than the surface roughness when the component is used as a standard. Specifically, in this embodiment, as shown in FIG.
The surface roughness 58A of the 6A and the surface 58A of the shield ring 58 are made larger than the surface roughness when a normal standard is used, and irregularities 80 and 82 are formed. Similarly, as shown in FIG. 3, the lower surface (ejection surface) 66A of the shower head portion 66 has a surface roughness larger than that of a normal standard use, so that irregularities 84 are formed. I have. The surface roughness of the side surface as well as the lower surface of the shower head 66 may be increased. By increasing the surface roughness in this way, it is possible to improve the corrosion resistance as described later. FIG. 4 shows the irregularities 80 on the surface of each of the components 26, 58, 66,
It is the enlarged view which showed the state of 82 and 84 typically, and the surface roughness was set large.

In order to increase the surface roughness of each component such as the mounting table 26, the shield ring 58 and the shower head 66, the surface may be blasted using, for example, alumina particles having a predetermined particle size. In order to control the surface roughness, the particle size of the alumina-based particles to be used may be selected. In this case, for example, when amorphous carbon is used as the mounting table 26 and the shield ring 58, the surface roughness of the standard product is around 1.7 μm, so the surface roughness here is about 3.0 to 10.0. Set within the range. Further, for example, when aluminum is used as the material for the shower head section 66, the surface roughness of the standard product is about 0.4 μm, and the surface roughness here is in the range of about 0.7 to 2.4 μm. Set.

Next, a description will be given of a film forming process performed by using the apparatus configured as described above. First, in the film forming apparatus after the cleaning processing or in the film forming apparatus immediately after the apparatus is assembled, the materials of various members are exposed, and in this state, the film forming processing is not performed directly on the wafer surface. A precoating process for applying the same thin film as the film forming material on the surface of the component in the container 22 is performed. In this precoating process, the same kind of gas as in the process is flowed without placing the wafer W on the mounting table 26, and various process conditions such as process pressure and process temperature are set to, for example, Under the same process conditions, a thin film of, for example, tungsten silicide (WSix) is precoated on the inner wall surface of the processing container 22, the mounting table 26, the shield ring 58, the surface of the shower head 66, and the like. To maintain high reproducibility. After pre-coating is performed in this way,
A film formation process for actually depositing a film on the surface of the semiconductor wafer W is performed. First, the gate valve 64 provided on the side wall of the processing container 22 is opened, the wafer W is carried into the processing container 22 by the transfer arm, and the lifter pins 28 are pushed up to transfer the wafer W to the lifter pins 28. Then, the lifter pin 28 is lowered by lowering the push-up bar 32, and the wafer W is mounted on the mounting table 26.

Next, a gas required for film formation such as WF ₆ , SiH ₂ Cl ₂ or the like is supplied as a processing gas from a processing gas source (not shown) to the shower head section 66 by a predetermined amount and mixed therewith. The gas is supplied substantially uniformly into the processing container 22 from the gas injection holes 74 on the lower surface of the substrate. At the same time, the exhaust port 6
The processing vessel 2 is suctioned and evacuated from 0 to
2 is set to a predetermined degree of vacuum, and the heating lamp 44 located below the mounting table 26 is driven while rotating to emit heat energy. The radiated heat rays pass through the transmission window 40 and then irradiate the back surface of the mounting table 26 to heat it.
Since the mounting table 26 is very thin, it is quickly heated,
Therefore, the wafer W placed thereon can be quickly heated to a predetermined temperature. The supplied mixed gas causes a predetermined chemical reaction, and a film of, for example, tungsten silicide (WSix) is deposited and formed on the wafer surface according to the film forming conditions.

Regarding the process conditions during the film forming process, the process pressure is, for example, about 0.1 to 5 Torr, and the process temperature is about 500 to 600 ° C. Such a film forming process is continuously performed on a large number of wafers, for example, 25 wafers. If the surface of each component in the processing chamber 22 is peeled off during the continuous process, it may cause particles or the like. Unnecessary film adheres, so to remove it,
Next, a cleaning process is performed. In this cleaning process, for example, a ClF ₃ gas is flowed as a cleaning gas from the shower head 66 into the processing chamber 22 to remove unnecessary tungsten silicide films deposited on the surface of each component by an exothermic reaction with the cleaning gas. Evaporate and remove. At the time of this cleaning process, the temperature of the mounting table 26 is adjusted to an optimum value for cleaning, for example, 200 to
Maintain at a temperature of about 250 ° C.

When the cleaning process is completed, the pre-coating process described above is performed again, and then a film forming process on a semiconductor wafer is performed. Hereinafter, each of the above-described steps will be repeatedly performed. By the way, in such a series of processing, each component in the processing container 22 is exposed to corrosive gas, and its surface tends to be corroded.
For example, during film formation, each component is exposed to a highly corrosive corrosive gas such as HCl gas or Cl gas generated by a film formation reaction, and a strongly corrosive cleaning gas (ClF ₃ ) itself during a cleaning process. Exposure to susceptibility to damage. However, in the present embodiment, since the components such as the mounting table 26, the shield ring 58, and the shower head 66 are set to have a larger surface roughness than the standard surface roughness. In addition, corrosion resistance is reduced, and the corrosion resistance is greatly improved, so that the service life can be extended.

As described above, the reason that the surface is hardly corroded by increasing the surface roughness is that when the surface roughness is small, the film formation amount per unit area is large, and the reaction is accompanied by the reaction during cleaning. While the calorific value increases and corrosion becomes easy, when the surface roughness is large, the amount of film formed per unit area decreases and the calorific value accompanying the reaction decreases, making it difficult to corrode. It is presumed. Another reason is that the amorphous carbon on the surface of each component reacts with the ClF ₃ gas to generate carbon fluoride during the cleaning process, but the thermal stress at this time is reduced. Guessed. That is, the fluorine gas generated during the cleaning process and the mounting table 26,
The carbon from the shield ring 58 and the like reacts to form carbon fluoride, which is generated on the surface of each component, and has a different coefficient of thermal expansion between the carbon fluoride and the amorphous carbon as the base. However, as described above, when the surface roughness is large, the surface area increases, heat is dispersed, the surface temperature decreases, and the amount of carbon fluoride generated here decreases, As a result, it is presumed that the stress strain is reduced. In addition, it is assumed that such a large surface roughness also increases the effect of buffering stress strain.

In particular, by increasing the surface roughness of the mounting table 26, the contact area between the mounting table 26 and the back surface of the wafer can be reduced by that amount. It becomes possible. In the above embodiment, the case of setting a large surface roughness by performing such simple blast treatment on the surface of each part 26,58,66 is explained as an example, a plasma etching process on the surface, for example, O ₂ presence As shown in FIG. 5, the parts 26, 5
The tops of the projections on the uneven surface of 8, 66 may be cut off to some extent. According to this, the corrosion resistance of the surface can be further improved.

Next, Examples 1 to 5 and Comparative Examples 1 and 2 were actually evaluated for corrosion resistance using test pieces having various surface roughnesses. The results will be described. FIG. 6 is a diagram showing the evaluation results. In the figure, the material of the test piece is all amorphous carbon, and in Examples 1 to 5, the surface roughness Ra is variously changed from 3.0 to 7.4. Also,
In Example 5, the surface of the test piece used in Example 1 was O
₂ Plasma etching is applied. The surface roughness Ra of Comparative Example 1 is 1.7 μm, which is the conventional general surface roughness of an amorphous carbon component (mounting table, shield ring, etc.), and is a so-called standard product. Further, the surface roughness Ra of Comparative Example 2 was 0.5 μm, and the surface was finished in a substantially mirror-like state. The evaluation was performed by performing a pre-coat process + a film forming process of 25 wafers + a ClF ₃ cleaning process as one cycle, and visually observing how many cycles the surface of the test piece was damaged.

The presence or absence of powder-like particles was evaluated by bonding a carbon tape to the surface of the test piece and peeling it off. As shown in the figure, in the case of the standard product having a surface roughness of 1.7 μm shown in Comparative Example 1, the number of endurance cycles was 16, and the powder particles were not peeled off, which was not preferable. In the case where the surface roughness shown in Comparative Example 2 was 0.5 μm (substantially a mirror surface state), the surface was roughened only in the durability cycle number of four times, and the powder particles were peeled off. Corrosion was degraded and was not even more desirable. In contrast, the surface roughness was 3.0.
In the case of Examples 1 to 5 described above, the number of endurance cycles was larger than that of Comparative Examples 1 and 2, and increased to 19 to 40 times, indicating that the corrosion resistance was improved and preferred. Here, in Examples 2 to 4, the number of endurance cycles was 40, but this number was sufficient for the durability, and the test was stopped more times. The number of endurance cycles is expected to be even greater.

In Example 1, the powder particles were peeled off, in Examples 2 and 3, the powder particles were slightly peeled off, and further, in Example 4, the powder particles were not peeled off. The greater the surface roughness, the better the corrosion resistance. However, if the surface roughness exceeds 10.0 μm, the film deposited on the apex of the convex portion of the uneven surface of the test piece peels off and causes particles, so the upper limit of the surface roughness is about 10.0 μm. is there. Therefore, when amorphous carbon was used as the component material, it was found that the surface roughness was preferably in the range of 3.0 to 10.0 μm. This range of surface roughness can be applied to materials other than amorphous carbon, and is 1.76 (= 3.0 / 1.7) to 5.88 (= 1) of the surface roughness of the standard product.
A component having a surface roughness in the range of 0.0 / 1.7) times may be used.

As is apparent from a comparison between the first embodiment and the fifth embodiment, even if the surface roughness is the same, the surface is subjected to the plasma etching treatment as in the fifth embodiment. From 23 times to 23 times, the surface of the powder particles did not peel off, indicating that the corrosion resistance could be further improved. FIG. 7 (A) shows electron micrographs of the surface of Example 2 having a surface roughness of 4.3 μm before and after the experiment. According to this, after the experiment, fine carbon pieces were seen on the entire surface and peeled off. It was observed that it did not fall. On the other hand, FIG. 7B shows a surface roughness of 1.7.
Electron micrographs before and after the experiment of the surface of Comparative Example 1 having a thickness of μm are shown. According to this, after the experiment, it was possible to observe a state in which irregularities spread as if carbon had fallen off the surface.
In the above embodiment, WF ₆ or SiH ₂ C
Using l _2, a case has been described using a ClF ₃ gas as a cleaning gas for example, but is not limited to these gases. The object to be processed is not limited to a semiconductor wafer, and the apparatus of the present invention can be applied to an LCD substrate, a glass substrate, and the like.

[0026]

As described above, according to the film forming apparatus of the present invention, the following excellent functions and effects can be exhibited. By increasing the surface roughness of the components in the processing container, the amount of unnecessary film formed per unit area is reduced, and the calorific value of the portion is reduced, or the surface temperature is reduced. Corrosion can be improved. Further, by performing plasma etching on the surface, the corrosion resistance can be further improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a film forming apparatus according to the present invention.

FIG. 2 is a partially enlarged view showing a mounting table and its peripheral portion in FIG. 1;

FIG. 3 is an enlarged view showing a portion A in FIG.

FIG. 4 is an enlarged view schematically showing the state of irregularities on the surface of each component in the processing container.

FIG. 5 is an enlarged view showing a state in which a top of a convex portion on a concave-convex surface of a component is removed by plasma etching.

FIG. 6 is a diagram showing the evaluation results of corrosion resistance of Examples of the present invention and Comparative Examples.

FIG. 7 is a view showing electron micrographs of the surfaces of the components of the example of the present invention and the comparative example.

FIG. 8 is a schematic configuration diagram showing a conventional general film forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 20 Film-forming apparatus 22 Processing container 26 Mounting table (part) 40 Transmission window 44 Heating lamp 58 Shield ring (part) 66 Shower head part (part) 68 Head main body 74 Gas injection hole W Semiconductor wafer (workpiece)

Claims (7)

[Claims] An object to be processed is mounted on a mounting table installed in a processing container capable of being evacuated, and a film forming process is performed by introducing a film forming gas into the processing container. In the membrane device, the surface roughness of the components provided in the processing container,
A film forming apparatus characterized in that the surface roughness is set to be larger than the surface roughness when this component is used as a standard. 2. The film forming apparatus according to claim 1, wherein the component is the mounting table. 3. The film forming apparatus according to claim 1, wherein the component is a shield ring provided so as to surround a periphery of the mounting table. 4. The film forming apparatus according to claim 1, wherein the component is a shower head provided to face the mounting table. 5. The material of the mounting table or the shield ring is AlN, Al ₂ O ₃ , SiC, SiO ₂ , Si ₃ N _4.
4. The film forming apparatus according to claim 2, wherein the film forming apparatus is any one of amorphous carbon and amorphous carbon. 6. When the material of the mounting table or the shield ring is amorphous carbon, the surface roughness is 3.
The film forming apparatus according to claim 5, wherein the thickness is within a range of 0 to 10.0 m. 7. The component according to claim 1, wherein the surface of the component is subjected to a plasma etching process.
A film forming apparatus according to any one of the above.