JP2011054894A - Method for forming oxide film - Google Patents

Abstract

An object of the present invention is to realize a film having excellent interface characteristics by improving the adhesion between an oxide film and a CVD film.
In a processing chamber, an oxidation process for supplying only an ozone-containing gas to a processing substrate to form an oxide film on the processing substrate, and a CVD source gas for the processing substrate that has undergone the oxidation process are provided. A CVD process is performed in which an ozone-containing gas is supplied to form an oxide film made of an oxide of the component of the source gas on the processing substrate. The film formation speed in the initial stage of the CVD process is controlled to be smaller than the film formation speed in the oxidation process. Further, an annealing step of exposing the treated substrate subjected to the CVD step to an ozone-containing gas atmosphere or an ozone-containing gas atmosphere irradiated with light having a wavelength in the ultraviolet region, and the treated substrate subjected to the annealing step to the CVD step It is good to have a process provided to. More preferably, the process of subjecting the processed substrate that has undergone the annealing process to the CVD process is repeated a plurality of times.
[Selection] Figure 1

Description

  The present invention relates to an oxide insulating film manufacturing process to which an ozone-containing gas is applied, and a semiconductor manufacturing technology such as a polysilicon TFT and an FET gate oxide film.

By introducing ozone gas into the semiconductor process, the temperature of the film forming process can be lowered. In particular, in Si oxidation, oxidation is possible even at 400 ° C. or lower using photoexcited ozone (O ( ¹ D)) generated by irradiating ozone with ultraviolet light (wavelength: 200 to 300 nm). Here, the reaction formula of ozone photolysis is “O ₃ → O ( ¹ D) + O ₂ ”. Si oxide films produced at 400 ° C. or lower by photoexcited ozone oxidation have excellent insulating characteristics and interface characteristics, and thus have been found to be useful as gate insulating films for TFTs and FET elements (Patent Document) 1). Furthermore, by applying photo-excited ozone oxidation to the polysilicon substrate, an oxide film having a uniform thickness was obtained on the polysilicon substrate surface (Non-patent Document 1). Here, unlike a single crystal silicon wafer, a polysilicon substrate has a number of crystal orientation planes deposited on the surface. Therefore, in order to obtain an oxide film with a uniform thickness, the oxidation rate is influenced by the crystal orientation. It is required not to receive. However, since the conventional Si oxidation using oxygen cannot form a uniform oxide film on the polysilicon substrate, photoexcited ozone oxidation is extremely important in the production of polysilicon devices and low-temperature fabrication devices (for example, flexible displays). Expected to play a role.

In addition to oxidation, photoexcited ozone is useful for low-temperature deposition of an oxide film by CVD. For example, when photoexcited ozone and a CVD process are performed using tetraethoxysilane (hereinafter referred to as TEOS) or hexamethyldisilane (hereinafter referred to as HMDS) as a source gas, a SiO ₂ film can be formed at 400 ° C. or lower. is there. The CVD-SiO ₂ film thus formed has a low concentration of impurities in the film and excellent insulation as compared with plasma CVD, which is another low-temperature SiO ₂ film forming process (Patent Document 2).

  For this reason, the CVD technique using photoexcited ozone has attracted attention as a low temperature film forming technique. Such a technique is particularly effective for making a device element on a material (glass or plastic) having a low melting point of the substrate. When the TFT 103 or the FET 104 is formed on the material 101 having a low melting point as shown in FIG. 2 on which Si single crystal, polysilicon, or amorphous silicon 102 is deposited, the material 101 deteriorates if a high temperature process is required. is there.

JP 2006-270040 A JP 2006-80474 A JP 2008-243926 A

N. Kameda1 et al. “J. of Electrochem. Soc.” Vol. 154 H769, 2007

When an SiO ₂ film is produced as a gate insulating film by CVD using photoexcited ozone at a low temperature, the interface characteristics of SiO ₂ are poor. Since the interface characteristics greatly affect the operation performance of the TFT / FET, it is necessary to improve the interface characteristics. On the other hand, the SiO ₂ film produced by directly oxidizing Si with photoexcited ozone has excellent interface characteristics, but it is difficult to produce a film thickness of 5 nm or more at a low temperature because the atomic diffusion rate is low at a low temperature. (Patent Document 1). In the low-temperature polysilicon TFT / FET, the thickness required for the gate oxide film is currently about 50 to 100 nm, so that the CVD film forming method must be applied.

Therefore, an oxide film by direct oxidation is first formed on polysilicon, and then a CVD process is performed to form a direct oxide film having excellent interface characteristics at the Si / SiO ₂ interface. A method of forming a film by CVD is conceivable.

  However, when forming a film in such a two-stage process, the adhesion between the underlying direct oxide film, the CVD process oxide film, and the CVD film becomes a problem. Due to the presence of the oxide film on the base, the surface is not hydrogen-terminated, and the adhesion between these films is inevitably deteriorated. It is conceivable that a low-density film is formed between the two films due to the deterioration of the adhesion, thereby causing an increase in charge trapping sites and a change in the dielectric constant of the film.

  Therefore, an oxide film forming method for solving the above-mentioned problem is an oxide film forming method for forming an oxide film on a processing substrate, wherein only an ozone-containing gas is supplied to the processing substrate to oxidize the processing substrate. An oxidation process for forming a film, and a CVD source gas and an ozone-containing gas are supplied to the processing substrate that has undergone the oxidation process to form an oxide film made of an oxide of the component of the source gas on the processing substrate. It has a CVD process.

  In the initial stage of the CVD process, when the film forming speed is controlled to be smaller than the film forming speed of the oxidizing process, the adhesion between the oxide film on the substrate and the CVD film is further increased. As an aspect of the film forming speed, for example, a method in which the film forming speed is made smaller than the film forming speed in the oxidation process immediately after the start of the CVD process, and is increased to a predetermined film forming speed after a certain time has passed. There is a method in which immediately after the start of the CVD process, the film formation rate is increased over time from a state where the film formation rate is 0 to a predetermined film formation rate. The film forming speed can be controlled, for example, by adjusting any of the pressure of the system related to the CVD process including the processing substrate, the flow rate of ozone-containing gas, and the flow rate of CVD source gas. In the oxidation process and the CVD process, when the processing substrate is irradiated with light having a wavelength in the ultraviolet region, ozone in each process is excited and the efficiency of the oxidation process is increased. In this case, the film forming speed can be controlled by adjusting the illuminance of the light in the CVD process.

  Further, an annealing step of exposing the treated substrate subjected to the CVD step to an ozone-containing gas atmosphere or an ozone-containing gas atmosphere irradiated with light having a wavelength in the ultraviolet region, and the treated substrate subjected to the annealing step to the CVD step In addition, the adhesion between the oxide film on the substrate and the CVD film is further enhanced. When a plurality of processes for subjecting the processed substrate subjected to the annealing process to the CVD process are repeated, in addition to improving the adhesion between the oxide film and the CVD film, the film quality of the CVD film is improved.

  According to the above invention, the adhesion between the oxide film and the CVD film is enhanced, and the production of a film having excellent interface characteristics is realized.

The schematic block diagram which showed the film forming process apparatus which concerns on embodiment of invention. Sectional drawing which showed schematic structure of the semiconductor substrate formed by the film forming process which concerns on a prior art. The schematic block diagram which showed the specific structural example of the processing chamber which concerns on invention. (A) The flowchart figure which showed the procedure of the film forming method which concerns on invention, (b) The schematic sectional drawing which showed the layer of the oxide film formed in the process board | substrate by the said film forming method. (A) Schematic configuration diagram showing an MIS capacitor formed by depositing an Al electrode on the SiO ₂ film of the processing substrate formed by the film forming processes P1 and P2, and (b) interface state density of the MIS capacitor. The JE characteristic figure of a MIS capacitor. The schematic sectional drawing of the board | substrate which showed the layer interposed between a direct oxide film layer and a CVD film layer. The high frequency (100 MHz) CV characteristic figure in case the processing time of P1 process is 0 minute, 3 minutes, and 10 minutes. The figure which showed the time schedule of control of the film forming speed which concerns on Embodiment 2 of invention. The characteristic view which showed the saturation capacity | capacitance of the CV characteristic at the time of changing the conditions of HMDS gas flow volume. The flowchart figure which showed the procedure of the film forming process which concerns on Embodiment 3 of invention.

(Embodiment 1)
The film forming process apparatus 1 according to the first embodiment of the invention shown in FIG. 1 includes a processing chamber 205 that stores a processing substrate to be subjected to an oxidation process and a CVD process. The oxidation process and the CVD process are processed in the same chamber. That is, in the processing chamber 205, only an ozone-containing gas is supplied to the processing substrate, and an oxidation process for forming an oxide film on the processing substrate is performed. Next, a CVD process is performed in which a CVD source gas and an ozone-containing gas are supplied to the process substrate that has undergone this process to form an oxide film made of an oxide of the component of the source gas on the process substrate. The processing substrate to be oxidized may be other than Si. An example is aluminum oxidation.

  The ozone-containing gas used in the oxidation process and the CVD process is supplied from an ozone supply device 201. An ozone generator or a cylinder filled with ozone gas is applied to the ozone supply device 201. The ozone concentration of the ozone-containing gas is 1 to 100%. Examples of ozone gas having an ozone concentration of 100% include ozone gas obtained from an ozone beam generator shown in Japanese Patent Publication No. 5-17164.

A source gas used for CVD is supplied from a source gas supply device 202. Examples of the source gas include organic silicon-based gases such as HMDS and TEOS. The source gas generator 202 or the cylinder is applied to the source gas supply device 202. In the CVD process, a film other than SiO ₂ may be formed. For example, a HfO ₂ oxide film and a Si ₃ N ₄ film can be used.

  Gases supplied from the supply devices 201 and 202 are supplied to the processing chamber 205 via pipings 211 and 212 corresponding to vacuum (<0.1 Pa), respectively. Valves V01 and V02 for adjusting the flow rate are installed in the pipes 211 and 212, respectively.

  The treated ozone gas and raw material gas supplied to the processing chamber 205 are exhausted by the exhaust pump 207 through the pipe 213. The pipe 213 is also provided with a valve V03 exemplified as a variable flow rate valve or an open / close valve.

  In order to suppress ozone decomposition when the ozone passes through the pipe 211, a process for preventing ozone decomposition by polishing the inner surface of the pipe 211 is appropriately performed. The pipes 212 and 213 and the processing chamber 205 may be higher than room temperature. That is, when a low vapor pressure gas such as TEOS is used as the source gas, a heating mechanism is provided in the pipe and the chamber in order to prevent liquefaction of the gas in the pipe 212, the processing chamber 205, and the pipe 213.

  A specific configuration example of the processing chamber will be described with reference to FIG.

  The processing chamber 205 shown in FIG. 3 has one or more pipes 211 to 213 connected to the ceiling. If the ozone gas and the source gas are merged upstream of the processing chamber 205, only one pipe for introducing a mixed gas of the ozone gas and the source gas is connected. The processing chamber 205 may be provided with a pipe 214 for introducing a purge gas as necessary. In addition, at least one entrance / exit 215 for the processing substrate is provided at the end of the processing chamber 205.

  The processing chamber 205 is formed to be a vacuum-compatible furnace. The ultimate pressure of the chamber is about 0.01 Pa. It is desirable to provide a pressure gauge 221 in the ozone treatment furnace 205. The specification of the pressure gauge 221 may employ a measurement range pressure of 0.01 Pa to 10000 Pa. As a material constituting the furnace wall of the processing chamber 205, a material that can be used in a vacuum state up to 0.1 Pa exemplified by aluminum, SUS, and quartz glass and is not easily oxidized is adopted.

Further, when performing photo-ozone oxidation / photo-ozone CVD in the processing chamber 205, an ultraviolet light source 203 for irradiating the processing substrate 222 with ultraviolet light to be used for the oxidation and CVD is installed outside the processing chamber 205. . The processing chamber 205 is provided with an irradiation window 204 so that the ultraviolet light from the ultraviolet light source 203 is supplied to the processing substrate 222. The irradiation window 204 is made of a material that transmits light of 200 to 300 nm (for example, quartz glass, MgF _2, etc.). As the ultraviolet light source 203, a known light source that emits light including light having a wavelength of at least 200 to 300 nm may be applied. A shutter 206 is installed between the ultraviolet light source 203 and the transmission window 204. The shutter 206 can be opened and closed so that it can be opened and closed before and after the process. A material that absorbs or reflects at least light having a wavelength of 200 to 300 nm is employed as the material of the transmission window 204 (for example, Al).

  The processing substrate 222 is stored in the processing chamber 205 so that the light of the ultraviolet light source 203 directly hits the surface of the processing substrate 222. The processing substrate 222 is held on the susceptor 223. The susceptor 223 is installed so as to be movable in the processing chamber 205 by a rotation mechanism or a transport mechanism. The susceptor 223 may be heated by a heating mechanism as necessary.

  In the oxidation process and the CVD process, shared process conditions (ozone supply amount, CVD source gas supply amount, process pressure, light irradiation amount of the ultraviolet light source 203, process temperature (for example, the temperature of the susceptor 223), and exhaust speed (for example, exhaust) The pumping speed of the pump 207)) is appropriately controlled.

  The film forming method according to the present embodiment will be described more specifically with reference to FIG.

  As shown in FIG. 4A, the film forming method of the present embodiment is roughly composed of two stages. That is, it comprises a film forming process P1 in which only the ozone gas is supplied to the processing substrate to directly oxidize, and a film forming process P2 in which the CVD source gas and the ozone gas are supplied to the processing substrate having undergone this process to perform the CVD. . The process is consistently performed at low temperatures below 400 ° C.

  In the manufacturing process P1, only the ozone-containing gas is supplied into the processing chamber 205, and the CVD source gas is not supplied. In order to control the gas flow, an inert gas such as nitrogen or argon may be introduced. When using oxidation by light ozone, light is supplied from the ultraviolet light source 203 to the substrate.

  In the manufacturing process P2, the ozone-containing gas and the CVD source gas are supplied to the chamber 205. There is no problem in introducing an inert gas such as nitrogen or argon in order to control the gas flow. In the case of film formation by optical CVD, light is supplied from the ultraviolet light source 203 to the processing substrate 222.

  In the oxidation process P1 and the CVD film forming process P2, the process pressure, the ozone flow rate, the light irradiation amount, the light irradiation wavelength, and the light irradiation region may be different.

  A film structure as shown in FIG. 4B can be formed through the film forming processes P1 and P2. An oxide film 302 produced by the film production process P1 exists on the substrate 301, and an oxide film 303 produced by the film production process P2 exists on the oxide film 302.

In both the film forming processes P1 and P2, the process pressure is set to a range below the explosion limit of ozone. Further, the ultraviolet light 200 to 300 nm component of the light supplied from the light source 203 is an output in a range sufficiently larger than the ozone molecule density in terms of the number of photons. The light source 203 may be either a pulsed oscillation type using a laser or a continuous irradiation type using a lamp. The CVD source gas includes Si such as HMDS and TEOS when, for example, an SiO ₂ film is formed. In TEOS, which has a low vapor pressure at room temperature, the gas supply system piping may be heated to about 70 ° C. The HMDS and TEOS gas flow rates are in a sufficiently small range with respect to the ozone flow rate. This is because a large number of ozone molecules are required for decomposition for each molecule of source gas. If under vacuum, an interruption time may be provided between the film forming processes P1 and P2.

  The film forming processes P1 and P2 may be performed in separate chambers. In that case, the chamber is transported in a vacuum atmosphere. By making the film forming process P1 and the film forming process P2 into separate chambers, the influence of particles generated in the film forming process P2 on the film forming process P1 can be reduced. Further, by separating the processing chambers of the film forming process P1 and the film forming process P2, film formation can be performed in chambers according to the characteristics of the respective processes, so that it can be performed efficiently. For example, in the film forming process P1, it is possible to shorten the processing time of the process P1 by using the one having a shortened optical furnace length (gap length) in the chamber.

Next, examples of the present embodiment will be described. In this example, a SiO ₂ film was formed on a Si wafer. In the film forming process P1, a photo-ozone oxidation process was performed. The treatment substrate was Si (100). An ozone-containing gas having an ozone concentration of 90% or more was used, and its flow rate was set to about 100 sccm. A high pressure mercury lamp was employed as the light source for the film forming process P1. The substrate temperature was controlled to 100 ° C., the processing time of the process P1 was 10 minutes or less, and the film thickness of the film produced by the process P1 was controlled to 3 nm or less.

  After the film forming process P1, a film forming process P2 using the same light source in the same chamber was started. In the film forming process P2, photoexcited ozone CVD was performed. HMDS was used as the CVD source gas. The ozone-containing gas was used at the same concentration as in the film forming process P1. The flow rate of the ozone-containing gas was about 100 sccm, the flow rate of HMDS was 1 sccm, the processing time was 8 minutes, the film thickness was about 50 nm, and the substrate temperature was set to 100 ° C.

FIG. 5 shows the results of the interface characteristics of SiO _{2 formed} on the processing substrate manufactured under the above conditions. As shown in FIG. 5A, after the film forming processes P1 and P2, an Al electrode 404 was deposited on the SiO ₂ film 403 on the processing substrate 401 made of Si (100) to form a MIS capacitor. The illustrated SiO 2 films 402 and 403 are oxide films obtained by the film forming processes P 1 and P 2, respectively. FIG. 5B shows the interface state density calculated from the CV measurement by the quasi-static method. In order to enhance the adhesion between the Al and SiO ₂ film after the deposition of the Al electrode 404, PMA annealing is performed at 400 ° C. for 20 minutes in an N ₂ atmosphere of 0.1 atm. The interfacial order density was disclosed when the processing time (oxidation processing time) of the film forming process P1 was 0 minutes, 3 minutes, and 10 minutes. When the processing time of the film forming process P1 is increased, the minimum value of the interface state density is decreased and the gap width is also increased, so that the interface characteristics are greatly improved. That is, this result shows that the interface characteristics can be improved by performing the film forming process P1.

  On the other hand, characteristics determined by the entire film such as insulating characteristics are hardly affected by the film forming process P1. FIG. 6 shows JE characteristics in the MIS capacitor arrangement. When comparing the J-E characteristics of the capacitors formed by the film forming process P1 (treatment time 0 minutes, 3 minutes, 10 minutes) with different oxidation treatment times, almost no difference was observed. This is because the film thickness produced by the film production process P1 is 50 nm while the film thickness produced by the film production process P2 is 50 nm while the film thickness produced by the film production process P1 is 50 nm or less. It shows that the film quality determined by the characteristics of the entire film is hardly affected by the length of time of the film forming process P1.

The above example shows that the interface can actually be improved. Although there is no particular limitation on the process conditions, as a practical process, the ozone flow rate in the film forming processes P1 and P2 is in the range of 1 to 1000 sccm, and the partial pressure of ozone used in the Si oxidation and CVD processes is in the range of 0.1 to 1000 Pa. Among them, the light irradiation amount of 200 to 300 nm used for the film forming processes P1 and P2 is in the range of 1 to 1000 mW / cm ² . The HMDS gas used for the film forming process P2 is 1 to 100 sccm, and the processing time of the film forming process P1 is about 0.1 second to 1 hour.

  As described above, according to the film forming process apparatus 1 of the first embodiment, an oxide film having excellent interface characteristics can be produced. In addition, an oxide film can be formed at a low temperature of 400 ° C. or lower. By using a light source having a wavelength of 200 to 300 nm in combination, an oxide film can be formed at a low temperature of 200 ° C. or lower. A thick film of 100 nm or more can be formed.

  The oxidation process (P1) and the CVD process (P2) may be performed in separate chambers. Transport between the oxidation process chamber and the CVD process chamber is performed in an environment having a vacuum degree of 1 Pa or less. As described above, by executing the process P1 and the process P2 in separate systems, the mixing of particles in the oxidation process can be reduced, and a film having better interface characteristics can be produced. And the film-forming speed | rate in an oxidation process rises, and shortening of an oxidation process processing time is implement | achieved.

(Embodiment 2)
In film formation in a two-stage process, the adhesion between the underlying direct oxide film, the CVD process oxide film, and the CVD film becomes a problem. Since an oxide film is present in the base when starting the CVD process, the adhesion at the interface is inevitably deteriorated because it is not a normal hydrogen-terminated surface. It is considered that due to this deterioration in adhesion, a low-density film is formed between the two films, causing an increase in charge trapping sites and a change in the dielectric constant of the film. That is, as shown in FIG. 7, when the CVD film 303 is formed when the oxide film 302 is directly on the substrate 301, a low-density layer 304 is formed between the film 302 and the film 303.

As an inevitable problem when performing two-stage film formation, there is a problem of adhesion between the two films. This corresponds to the presence of the film 304 shown in FIG. The presence of the film 304 can be seen from the saturation capacity of the CV characteristic of FIG. FIG. 8 is a high-frequency (100 MHz) CV curve when the processing time of the P1 process is 0 minutes, 3 minutes, and 10 minutes. The saturated capacity C _OX (802) is decreased when the processing time is 3 minutes and 10 minutes, compared to the saturated capacity C _OX (801) when the processing time of the film forming process P1 is 0 minutes. This occurs because the dielectric constant of the film has changed. This change ΔC _OX (802) is explained by the change in the film thickness ratio between the dielectric constant ε1 (about 3.9) of the film 302 and the dielectric constant ε2 (about 5.7) of the CVD film 303 by the film forming process P1. This cannot be explained unless a layer 304 having a low-density, near-vacuum dielectric constant (about 1) is assumed between the film 302 and the film 303, suggesting the presence of the film 304. Note that the thickness of the layer 304 is 1 nm or less. It is thought that the film 304 can be formed immediately after the start of the process P2.

  Therefore, in the second embodiment, the film forming process P2 can be solved by changing the film forming speed in the process and reducing the film forming speed immediately after the start of the process. As an aspect of controlling the film forming process, schedules S1 and S2 are exemplified as illustrated in FIG. In the schedule S1, the film forming speed is made smaller than the film forming process P1 immediately after the start of the film forming process P2, and is increased to a predetermined film forming speed after a predetermined time has elapsed. The schedule S2 is gradually increased from the state of the film forming speed 0 to the predetermined film forming speed as time passes immediately after the start of the film forming process P2. As described above, the film density between the direct oxide film and the CVD film can be increased by making the initial film forming speed of the film forming process P2 smaller than the film forming speed of the film forming process P1. In addition to the substrate temperature, the film forming speed can be controlled by changing the pressure in the processing chamber, the ozone-containing gas flow rate, the CVD gas flow rate, the light intensity of the light source (in the case of optical CVD), and the gas flow rate.

  As an example of this embodiment, an example in which adhesion is improved in the two-stage film formation will be described.

In this example, an SiO ₂ film is formed on a Si wafer. In the film forming process P1, direct photo-ozone oxidation was performed. Si (100) was adopted as the processing substrate. The ozone-containing gas has an ozone concentration of 90% or more, the gas flow rate is ˜100 sccm, and a high-pressure mercury lamp is used as a light source for direct oxidation. The substrate temperature was controlled to 100 ° C., the processing time of the process p1 was 10 minutes, and the film thickness to be produced was controlled to about 3 nm. After the film forming process P1, the film forming process P2 was started using the same light source in the same chamber. In the film forming process P2, photoexcited ozone CVD was performed. HMDS was used as the CVD source gas. The ozone-containing gas was used at the same concentration as in the film forming process P1. The ozone flow rate was set to about 100 sccm. The flow rate of HMDS was set to 0.1-1 sccm. The processing time of the film forming process P2 is 8 to 18 minutes. The film thickness is about 50 nm. The substrate temperature was set to 100 ° C.

In the film forming process P2, the HMDS gas flow rate was changed under the following conditions 1 to 4 in order to change the film forming speed.
Condition 1: HMDS flow rate 0.1 sccm until 1 minute after the start, then 1 sccm for 8 minutes.
Condition 2: HMDS flow rate 0.1 sccm up to 10 minutes after start, then 1 sccm for 8 minutes.
Condition 3: HMDS flow rate 1 sccm for 8 minutes immediately after the start.
Condition 4: CVD with a HMDS flow rate of 1 sccm for 8 minutes immediately after the start as the process P2 without performing the film forming process P1.

  The saturation capacity curves showing the CV characteristics under the above four conditions were compared.

  Respective saturation capacities correspond to saturation capacity curves (hereinafter referred to as curves) 1001 to 1004 for conditions 1 to 4 in FIG. First, the curve 1004 of condition 4 is the smallest. This corresponds to the absence of the film 304 due to the absence of the film forming process P1. On the other hand, the curve 1003 is the largest. This means that the influence of the film 304 is the largest among the above four conditions. The curve 1001 of the film with the CVD deposition rate reduced for 1 minute is closer to the curve 1004 than the curve 1003. Further, since the curve 1002 of the film with the CVD deposition rate lowered for 10 minutes is closer to the curve 1004 than the curve 1001, it can be formed so as to eliminate the film 304 by suppressing the initial deposition rate as much as possible. I was able to show.

(Embodiment 3)
In the present embodiment, in addition to the control of the film forming speed, the time during which the processing substrate is exposed to the ozone-containing gas or the photoexcited ozone atmosphere is intentionally introduced during the film forming process P2. That is, the adhesion between the oxide film and the CVD film can be further enhanced by ozone annealing by exposing the processing substrate to an atmosphere of ozone-containing gas or photoexcited ozone gas, and the CVD film quality can be improved (Patent Document 3).

  In the film forming process of this embodiment, as shown in FIG. 11, the film forming process P2 (CVD film forming) in the film forming processes P1 and P2 is divided into two stages of a process P2-1 and a process P2-2. -1 and P2-2 have ozone annealing process P3. The ozone concentration used in the process P3 may be approximately the same (2 to 100%) as the ozone concentration of the ozone-containing gas used in the film forming processes P1 and P2. As the ozone-containing gas for the process P3, an ozone-containing gas used for the film forming processes P1 and P2 may be applied. The apparatus configuration for executing the above process may be the same as the film forming process apparatus 1 disclosed in FIG.

Ozone annealing (process P3) is effective for a CVD film having a thickness of 1 to ₂ nm at a low temperature of 400 ° C. or lower due to the temperature dependence of the diffusion length of ozone or photoexcited ozone in the SiO ₂ film (Patent Document 3). .

In the flowchart of FIG. 11, in the film formation process P2-1 (CVD film formation), it becomes effective by performing the process P3 (annealing) so as to form a film with a film thickness of about 1 to 2 nm. In the film forming process P2-2 (CVD film forming), it is desirable that the film forming speed immediately after the start is small. Initial film interface state between the SiO ₂ which process P3 is by slowing the growth rate is formed by SiO ₂ surface and the processes P2-2 are precipitated when finished is because the better. As described above, the ozone adhesion is performed on the oxide film that has undergone the film forming process P1 by performing the ozone annealing in a state in which the CVD film is slightly deposited by the film forming process P2.

  Further, the process P3 may be performed once or more. For example, when the film forming process P2 is divided into n times to form film forming processes P2-1 to P2-n, the film forming process P2-i and the film forming process P2-i + 1 (1 ≦ i ≦ n−1) A mode in which the process P3 is executed in between is mentioned. Thus, in addition to improving the adhesion between the direct oxide film and the CVD film formation by performing the process P3 n-1 times in total, the film quality of the CVD film formed by the film formation process P2 is improved. Can do. As described above, ozone annealing can be performed in the chamber 205 in which the film forming processes P1 and P2 are performed. Alternatively, a chamber for ozone annealing may be provided separately. When ozone annealing is separately performed in a chamber, the surface of the CVD film can be prevented from being deteriorated by carrying it at 1 Pa or less.

As described above, according to the film forming process apparatus of Embodiment 3, it is possible to improve the adhesion at the interface of the SiO ₂ film formed by different processes in the two-stage film forming. Further, there is no need to increase the substrate temperature. Further, the adhesion effect is increased by using ultraviolet light. In addition, a plurality of processes can be performed in a single processing chamber, and the ozone-containing gas is shared by direct oxidation (film formation process P1), CVD (film formation process P2-n), and annealing (process P3). Therefore, inexpensive film formation is realized.

DESCRIPTION OF SYMBOLS 1 ... Film forming process apparatus 201 ... Ozone supply apparatus 202 ... Raw material gas supply apparatus 203 ... Ultraviolet light source 205 ... Processing chamber

Claims (9)

An oxide film forming method for forming an oxide film on a processing substrate,
An oxidation step in which only an ozone-containing gas is supplied to the processing substrate to form an oxide film on the processing substrate;
A CVD step of supplying a CVD source gas and an ozone-containing gas to the processing substrate that has undergone the oxidation step to form an oxide film made of an oxide of the component of the source gas on the processing substrate. An oxide film forming method.   The method for forming an oxide film according to claim 1, wherein a film forming speed in an initial stage of the CVD process is controlled to be smaller than a film forming speed in the oxidizing process.   3. The oxide film according to claim 2, wherein immediately after the start of the CVD process, the film forming speed is made smaller than the film forming speed of the oxidation process and is increased to a predetermined film forming speed after a predetermined time has elapsed. Forming method.   3. The method of forming an oxide film according to claim 2, wherein immediately after the start of the CVD process, the time is increased over time from a state where the film forming speed is zero to a predetermined film forming speed. 5. The film forming speed is controlled by adjusting any one of a system pressure, a flow rate of an ozone-containing gas, and a flow rate of a CVD source gas related to a CVD process including the processing substrate. The method for forming an oxide film as described in 1. above. 6. The oxide film forming method according to claim 2, wherein in the oxidation step and the CVD step, the processing substrate is irradiated with light having a wavelength in an ultraviolet region. The method for forming an oxide film according to claim 6, wherein in the CVD step, the film forming speed is controlled by adjusting the illuminance of the light. An annealing step in which the substrate subjected to the CVD step is exposed to an atmosphere of an ozone-containing gas or an atmosphere of an ozone-containing gas irradiated with light having a wavelength in the ultraviolet region;
8. The method for forming an oxide film according to claim 1, further comprising a step of subjecting the processed substrate that has undergone the annealing step to the CVD step.   The method for forming an oxide film according to claim 8, wherein the process of subjecting the processed substrate that has undergone the annealing process to the CVD process is repeated a plurality of times.

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