JPH0277579A - Method for cleaning deposited film forming device - Google Patents

Abstract

PURPOSE:To maintain the quality of a deposited film on a high level and to improve productivity by removing a silicon-based reaction product sticking to the inside of a reactor with gaseous ClF3 as a cleaning gas while supplying electric discharge energy. CONSTITUTION:When a silicon-contg. reaction product sticking to the inside of the reactor of a deposited film forming device for forming a deposited film by chemical vapor growth, the product is removed with gaseous ClF3 as a cleaning gas while supplying electric discharge energy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for cleaning an apparatus for forming a deposited film by a wet method or a dry method (particularly a gas phase method such as a microwave plasma CVD method). In particular, the present invention relates to an invention that is effective in cleaning a deposited film forming apparatus that forms deposited films that can be suitably used as semiconductor elements such as photoconductive members for electrophotography, line sensors for image input, imaging devices, and solar cells. .

Furthermore, the present invention relates to a cleaning method that is extremely effective for an apparatus that forms an amorphous semiconductor deposited film containing silicon as a main component by microwave plasma CVD.

[Prior Art] A method of forming a deposited film on a substrate using a vapor phase method has been used in the production of semiconductor elements such as photoconductive members for electrophotography, line sensors for image input, imaging devices, and solar cells. It is used. Formation of a deposited film by this vapor phase method is suitable in that a deposited film with uniform characteristics over a large area can be formed.

However, some of the reaction products deposit or adhere as powder on parts other than the intended substrate, such as the inner wall of the reaction vessel, and this deposit or adhesion peels off, flies off, and adheres to the substrate. This may be one of the causes of film defects such as pinholes in the deposited film.

As a method for cleaning a deposited film forming apparatus to remove reaction products adhering to the inside of the reaction chamber, etc., US Pat. No. 4,529
, 474, JP-A-59-142839, etc., there is a known method for removing the reaction product using a mixed gas of carbon tetrafluoride CF4 and oxygen 02 as an etchant. There is. Specifically, U.S. Patent 4,
No. 529,474 discloses that polysilane adhering to the inner wall of the reaction chamber can be removed by using a mixed gas of CF and 02 for cleaning a reaction chamber in which an amorphous silicon deposited film is formed.

Furthermore, Japanese Patent Application Laid-open No. 142839/1983 discloses that a mixed gas of CF4 and 0° is effective for cleaning a plasma CVD apparatus for forming a silicon carbide film.

By the way, there are various methods for forming a deposited film using a vapor phase method. As one of these methods, the so-called microwave plasma CVI) method using microwaves is known.

The method of forming a deposited film on a substrate by the microwave plasma CVD method (hereinafter referred to as μW-PCVD method) is attracting attention because it enables high-speed film formation and has high utilization efficiency of raw material gas. ing. Such μW −P
As one method for forming a deposited film using the CVD method, a raw material gas for forming a deposited film is introduced into a space surrounded by a plurality of substrates, and a discharge is generated in the space using microwave energy to form a deposited film on the substrate. There is a way to form.

Such a deposited film forming method using microwave energy is carried out using the following apparatus and film forming method.

Hereinafter, each part of the deposited film forming apparatus and the film forming procedure will be explained according to the drawings.

FIG. 1 is a schematic side cross-sectional view of a deposited film forming apparatus using the μw-pcvo method, and FIG. 2 is a plan cross-sectional view of the apparatus. FIG. 3 is an explanatory diagram schematically showing the entire apparatus.

The deposited film forming apparatus shown in FIGS. 1 and 2 is constructed as follows. That is, a reaction vessel (101
, 201), Amemina ceramic microwave introduction window (102, 202), microwave waveguide (103)
, exhaust pipe (104, 204), cylindrical base (105°2
05) (In addition, when the substrate is plate-shaped, the plate-shaped substrate is attached to the surface of a cylindrical substrate holder (1 (17, 207) using a jig not shown, and a deposited film is formed. ), a heater for heating the substrate (107°), a vibrator for introducing source gas (108, 208), and a motor for rotating the substrate (110). .GeL, H2
It is connected to cylinders (not shown) of source gases such as ゜CH, , C, Hffi, B, H, , PH, etc. via a valve (not shown) and a mass flow controller (not shown). Further, the exhaust pipe (104, 204) is connected to a diffusion pump (not shown).

A brief description of the entire apparatus for forming a deposited film using the .mu.w-pcvo method is as shown in the schematic explanatory diagram of FIG. That is, 2.45G11z microwave power supply 3
11 connects an isolator 312, a power monitor 313, and a stub tuner via a waveguide 303.
uner) 314 to the reaction vessel 301. The isolator 312 serves as an absorber that prevents the microwave generated by the microwave power source 311 from returning to the microwave power source. The power monitor 313 monitors the power of incident waves and reflected waves, and the stub tuner 314 adjusts the incident power and reflected power. The raw material gas supplied from the raw material gas supply device 310 is introduced into the reaction vessel through the gas introduction vibe 308. An exhaust pump 315 is connected to the reaction vessel 301 via an exhaust pipe 304.

The deposited film is formed by an individual using the deposited film forming apparatus described above with reference to FIGS. 1 and 2 as follows.

First, a cylindrical substrate (
105, 205) and the base rotation motor (11
0), and a diffusion pump (not shown) is operated to reduce the pressure in the reaction vessel (101, 201) to 10-'Toor or less. Next, a heater for heating a cylindrical substrate (10
In step 7'), the temperature of the cylindrical substrate is controlled to a desired temperature of 20°C to 400°C.

When the temperature of the cylindrical substrate (105, 2 (15) reaches the desired degree, the desired raw material gas is introduced from the gas cylinder (not shown) through the gas introducing vibrator (108, 208) into the discharge space (
106, 206) (that is, the film forming space).

Then, the internal pressure of the discharge space is set to a desired pressure of I Torr or less.

After the internal pressure stabilizes, the microwave power source (not shown) is connected to the waveguide (103) and the microwave introduction window (102, 202).
Microwave energy is introduced through the discharge space M (106,206). The source gas is decomposed by this microwave energy, and a desired deposited film is formed on the cylindrical substrate.

In addition to using the μw-pcvn method, which has excellent gas decomposition efficiency, by using the device configuration and film formation method described above, the raw material gas is reduced to approximately 1% in the discharge space.
00% decomposition and a deposited film is formed on the substrate. Therefore, it has traditionally been considered unnecessary to clean the inside of the reaction vessel used for film formation using the μW-PCVD method, and there are references that point out that cleaning the inside of the reaction vessel is necessary in such a film formation method. is not found.

[Problems to be Solved by the Invention] However, when a deposited film is formed many times without cleaning using the above-mentioned μW-PCVO device, film defects such as pinholes actually occur in the deposited film, and the deposition When the film was applied to a photoconductive member for electrophotography, a phenomenon was observed in which the number and area of minute image defects gradually increased. This has turned out to be a major problem in the production of photoconductive members for electrophotography.

Of course, such problems do not only occur in photoconductive members for electrophotography, but also occur in fields that require uniform deposited films.

Furthermore, it has been found that the deposits adhering to the inner wall of the .mu.w-PCVD apparatus cannot be effectively removed using conventional methods for cleaning deposited films.

The present invention has been made in view of the problems of the prior art described above, and an object of the present invention is to provide a cleaning method that can reliably prevent manufacturing defects due to unnecessary metamorphoses in a deposition forming apparatus for efficiently manufacturing a deposited film. It is an object.

Another object of the present invention is to suppress the occurrence of image defects in the photoconductive member for electrophotography by the μw-pcvo method when the deposited film is applied to the photoconductive member for electrophotography, and to improve productivity. An object of the present invention is to provide a method for cleaning a deposited film forming apparatus.

Still another object of the present invention is to provide a method for cleaning a deposited film forming apparatus that can improve productivity by effectively cleaning altered substances adhering to the inner wall of a reaction vessel.

[Means for Solving the Problem J The problem described above is that in a method for cleaning a deposited film forming apparatus that forms a deposited film, reaction products that have adhered to the interior of the reaction vessel during the formation of the deposited film are removed using ClF5 gas. A method for cleaning a deposited film forming apparatus characterized in that the deposited film is removed by a method of cleaning a deposited film forming apparatus,
A step of introducing the deposited film forming gas into a circulation space in the deposited film forming apparatus through which the deposited film forming gas can flow, a step of stopping the introduction of the gas, and a step of ClF3 after the stopping step.
A method for cleaning a deposited film forming apparatus, comprising the step of introducing a gas into the circulation space, and the step of introducing the deposited film forming gas, the stopping step, the CLF, and the gas introducing step in this order. The problem has been solved by a cleaning method for a deposited film forming apparatus according to claim 6, which repeats a plurality of times.

The method for cleaning a deposited film forming apparatus of the present invention includes a cleaning method for a deposited film forming apparatus that forms a deposited film by a vapor phase method, in which microwave energy is used to clean a deposited film on a substrate placed in a reaction vessel. It is preferable to use CIFg gas to remove reaction products adhering to the inner wall forming the gas circulation space of the reaction vessel when forming the reaction vessel.

By implementing the present invention, unnecessary modified products adhering to the inner wall of the reaction vessel can be effectively removed. This prevents the metamorphosed material adhering to the inner wall of the reaction vessel from falling onto the substrate on which the deposited film is formed, and prevents film defects such as pinholes from occurring in the deposited film. When the deposited film is applied to a photoconductive member for electrophotography, it is possible to significantly suppress the occurrence of image defects and provide an excellent photoconductive member for electrophotography from which high-quality images can be obtained.

Furthermore, since the manufacturing yield can be significantly improved, productivity can be significantly improved.

The present invention was made based on the following findings obtained by the inventor.

In other words, as described above, when a silicon deposit film is repeatedly formed using the μW-PCVD method, a small amount of the reaction product adheres as a film to parts other than the target substrate, that is, the inner wall of the reaction vessel. (It turned out that this film does not pose a problem if the film is formed only a few times, but if the film is repeatedly formed without performing the cleaning process, the thickness will gradually increase each time. Eventually, they begin to peel off.The peeled off pieces fly inside the reaction vessel and attach to the substrate on which the deposited film is to be formed, and this is one of the causes of film defects such as spherical protrusions and pinholes in the deposited film. It becomes one.

Such deposits are different from the deposited film formed on the substrate by the film forming method (μW-PCVD method), and are also deposited on the inner wall of the reaction vessel when forming the deposited film by conventional, for example, high-frequency plasma CVD method. It has been found that this material is different from the so-called polysilanes that can be removed by, for example, plasma etching using CF4 and 0□. Furthermore, the analysis results by the present inventors revealed that these deposits were denatured products of silicon production.

Based on these findings, the inventors of the present invention conducted extensive research through trial and error to find a means to effectively remove the above-mentioned metamorphosed products. It was found that metamorphosed materials adhering to the inner wall of the reaction vessel could be effectively removed, and film defects in the deposited film were significantly suppressed.

As a result, it was confirmed that the manufacturing yield could be improved, resulting in a significant improvement in productivity, and that the object of the present invention could be achieved.

Hereinafter, the effects of the cleaning method of the present invention will be specifically explained based on experimental examples.

Experimental Example 1 First, in this experiment, μW −P shown in FIGS.
A deposited film forming apparatus using the CVD method was used.

After pressing 5CIIIX5CIO aluminum substrates onto the inner walls of the reaction vessel (ill, 211) at several locations, an amorphous silicon film with a thickness of 10 μm was placed on the cylindrical substrate (105, 205) according to the method described above and the preparation conditions shown in Table 1 below. deposited.

Next, after removing the cylindrical substrate on which the amorphous silicon film was deposited from the reaction vessel, a new cylindrical substrate was placed in the reaction vessel, and the silicon deposited film was similarly deposited on the cylindrical substrate. .

This process was repeated for 10 cycles.

Table 1 Next, the aluminum substrate was peeled off from the inner wall of the reaction vessel and transferred to the high-frequency plasma CVD apparatus shown in Fig. 4.The metamorphic material accumulated on the aluminum substrate was removed by etching using various etching gases. I did it.

Here, the aluminum substrate is μW −P shown in Fig. 1 and Fig. 2.
The reason for moving from a deposited film forming apparatus using the CVD method to the high-frequency plasma CVD apparatus shown in FIG. 4 is that conventional etching gases (such as CF gas and 02 This is to compare the etching effects of ClF3 gas and ClF3 gas.

In FIG. 4, 401 is a reaction vessel, 402 is a substrate, and 40
3 is a heater for heating the substrate, 404 is 13.56MHz
a high-frequency power supply; 405 is a raw material gas supply system for forming a deposited film;
407 is an exhaust system, and 408 is a high frequency electrode. In this experiment, etching gas was supplied from the raw material gas supply system 405 to the reaction vessel 401, and etching was performed under conditions of supplying high frequency power and under conditions of not supplying high frequency power.

At this time, the substrate temperature was maintained at 25° C. by a cooling device (not shown). The etching treatment time was 30 minutes.

The etching condition was evaluated based on the area of the etched portion. 0 indicates that the metamorphoses on the aluminum substrate have been completely etched away, O1 indicates that more than half of them have been etched away, △ indicates that more than half of the metamorphoses have not been etched away, and X indicates that they are barely etched. And so. It should be noted that the judgment as to whether etching had been removed or not was made by visually observing whether or not there was any denatured material on the sample.

The etching conditions and results are shown in Table 2.

As shown in Table 2, it was found that ClF3 is suitable for etching the modified material mainly composed of silicon accumulated on the inner wall of the reaction vessel.

That is, it was confirmed that the etching rate of ClF3 is higher than that of conventional etching gases, which can be determined visually by a clear difference.

Furthermore, when using conventional etching gas such as CF++Og gas, good results could not be obtained even when etching was performed while supplying RF power, whereas when using ClF3 gas, it was not possible to obtain good results even when etching was performed while supplying RF power. It was confirmed that excellent cleaning effects could be obtained even without the use of

Table 2 Experimental Example 2> After repeatedly forming an amorphous silicon film on the cylindrical substrate (105, 205) in the same manner as in Experimental Example 1, this time a 5c
A m x 5 cm square aluminum substrate was placed on the inner wall of the reaction vessel (111, 2
11), an etching gas was introduced into the reaction vessel (101, 201) to remove the altered material on the aluminum substrate by etching.

Thereafter, the aluminum substrate was taken out from the reaction vessel and the etched state was evaluated using the same evaluation method as in Experimental Example 1.

Here, a cylindrical substrate on which an amorphous silicon film is deposited (
105, 205) from the reaction vessel, exhaust the inside of the reaction vessel, and then use the gas introduction vibrator (108°208).
Etching was introduced.

The etching conditions and results are shown in Table 3.

From Table 3, it was confirmed that excellent cleaning effects were obtained when (1:1F) gas was used as the etching gas, when no microwave energy was supplied, and when microwave energy was supplied.

Table 3 (Experimental Example 3) After forming a deposited film under the same deposited film forming conditions as in Experimental Example 2, Experimental Example 2 was performed except that the etching conditions were changed to those in Table 4.
The metamorphosed materials on the aluminum substrate were etched and removed using the same method as above. Thereafter, the etching state was evaluated using the same evaluation method as in Experimental Example 1.

The results are shown in Table 4.

From this experiment, it is possible to use ClF3 gas diluted, and the concentration of ClF3 gas is 100% to 1.
% range. ClF
3 gas is more preferably 70% to 5%, optimally 50%
Can be used at concentrations of ~10%. Also, as a diluent gas, Ar
In addition to inert gases such as , He, and Ne, N2. O
It was confirmed that x gas etc. can be used.

Furthermore, the following findings were obtained from another experiment.

Regarding the material of the reaction vessel, nickel alloy, aluminum alloy, 5S41 steel, SUS304, SUS316 are available.
．． 5tlS43Q, quartz glass, etc. can be suitably used.

Regarding the temperature inside the reaction vessel, a temperature of 20°C or more and 600°C or less can be preferably used, preferably 20°C or more and 300°C or less, and most preferably 25°C or more and 200°C or less.

Regarding the internal pressure of the reaction vessel after introducing ClF3 gas, the optimum range is selected as appropriate, but in normal cases it is 1 mToor or more 7
60 Torr or less, preferably 1 mTorr or more 10
0 Torr or less, optimally 1 mTorr or more 10To
It is desirable to set it to rr or less.

Table 4 (Experimental Examples 4 to 8) According to the preparation conditions shown in Table 5, a deposited film containing silicon as the main component was repeatedly formed in the same manner as in Experimental Example 1, and the inner wall of the reaction vessel was ClF
It was removed by etching in step 3. The etching conditions at this time were a ctps gas flow rate of 2 flow rates and a flow rate of 20300 mm. As can be seen from Table 5, good etching results were obtained in all cases.

Table 5 (Experimental Example 9) Five types of deposited films prepared in Experimental Examples 4 to 8 were prepared in the same manner as in Experimental Examples 4 to 8 under the conditions shown in Table 5. Next, the etching conditions (μ
After removing the metamorphoses on the substrate by etching in the same manner as in Experimental Example 2 (without introducing W power), the etching state was evaluated.

As a result, as in Experimental Examples 4 to 8, good etching results were obtained for all deposited films.

[Examples] Specific examples for demonstrating the effects of the present invention will be described below, but the present invention is not limited to these in any way.

<Example 1> Using the μW-PCVD apparatus shown in Figures i to 3,
According to the procedure described above and the manufacturing conditions shown in Table 6, electrophotographic photoconductive members were manufactured for 10 consecutive cycles. After the photoconductive member was taken out from the reaction vessel after the 10th cycle photoconductive member was obtained, ClF5 gas was supplied into the reaction vessel from the raw material gas supply pipe (108, 208, 308), and as shown in Table 7. After cleaning the inside of the reaction container under the same conditions, a photoconductive member for electrophotography was subsequently produced.

To explain using Fig. 5, the reaction vessel (101° 201
．． A cylindrical base (105, 205) is installed in (301) (
S,) and evacuated the inside of the reaction vessel (S,)t. Thereafter, source gas was introduced (SS) into the reaction vessel from the source gas supply device (310), and μW energy was introduced (S,) to form a deposited film (S,). Formation of the deposited film (S,) is performed by introducing a raw material gas for the second layer into the reaction vessel in place of the raw material gas for the first layer when the desired thickness of the first layer constituting the deposited film is obtained. This means that the second layer is formed and the third and subsequent layers are similarly formed to form a desired deposited film.

The formation of the deposited film (S,) is achieved by stopping the introduction of μW energy (
S6). After that, the substrate was taken out from the reaction container (101, 201, 301) (S8)
. After taking out the photoconductive member of the 10th cycle from the reaction vessel (S8), the reaction vessel (lot, 201°301)
The interior was evacuated (S9). Next, the etching gas is supplied to the raw material gas supply pipe (1,08) from the raw material gas supply device (310).
, 208) to the reaction vessel (101, 201, 301).
) is introduced in S,. ), reaction vessel (101, 201,
301) was cleaned (SZ).

After stopping the introduction of etching gas into the reaction container (S, □), the reaction container (101, 201, 301) was evacuated (S, , ), and the process returned to the substrate installation step (Sl).

Comparative Example 1-1> A photoconductive member for electrophotography was produced in the same manner as in Example 1 without cleaning the inside of the reaction vessel.

Comparative Example 1-2> In Example 1, CF and 0□ were used instead of ctps gas.
The inside of the reaction vessel was cleaned using the mixed gas as an etching gas under the conditions shown in Table 7, and then a photoconductive member for electrophotography was produced.

The photoconductive members for electrophotography produced in Example 1, Comparative Example 1-1, and Comparative Example 1-2 were used in a Canon copier N P
-7550 was set in an electrophotographic apparatus modified for experimental use, images were produced, and the occurrence of image defects was evaluated.

Specifically, using a solid black original, the ratio of white spots occurring in a copied image on solid black A3 paper was investigated.

A particularly good photoconductive member for electrophotography in which no white spots of 0.3 mo+ or more are observed is designated as A, and B is an excellent one in which several white spots of 0.3 mm or more but less than 0.5 mm are observed. 10 white spots with a diameter of 0.8 mm or more
C, 0.5ma+
Items with 10 or more white spots of 0.8 mm or less and some practical problems were rated as E, and samples with white spots larger than 0.8 aa that were not practical were evaluated as E.

The results are shown in Table 8.

Table 8 shows that by providing the cleaning step according to the present invention, film defects in the deposited film can be suppressed, and when the deposited film is applied to a photoconductive member for electrophotography, it is possible to obtain excellent quality electron beams with good image characteristics. It was found that a photographic photoconductive member could be stably obtained.

Table 6 Table 7 Table 8 <Example 2> A photoconductive member for electrophotography was produced in the same manner as in Example 1 except that the production conditions shown in Table 9 were used, and the same operations as in Example 1 were performed. , Evaluation of the occurrence of image defects, Example 1
Similar to the above, image defects were significantly suppressed and good results were obtained.

Table 9 (Example 3) A photoconductive member for electrophotography was produced according to the production conditions shown in Table 10, and the same operations as in Example 1 were performed, and the occurrence of image defects was evaluated. Good results were obtained in which image defects were significantly suppressed.

Table 10 [Effects of the Invention] According to the cleaning method for the deposited film forming apparatus of the above embodiment, the non-discharge area such as the reaction vessel of the deposited film forming apparatus for forming a functional deposited film mainly composed of silicon can be efficiently cleaned. It is possible to clean well, and as a result, the quality of the functional deposited film formed can be maintained at a high level, and productivity can be improved.

As explained in detail above, according to the method for cleaning a deposited film forming apparatus of the present invention, it is possible to efficiently remove deposits attached to the inner wall of a reaction vessel, etc. of a deposited film forming apparatus using microwave energy. .

As a result, the quality of the deposited film formed is maintained at a high level,
Moreover, since the manufacturing yield can be improved, productivity can be improved. For example, if a deposited film is formed after cleaning a deposited film forming apparatus using the cleaning method of the present invention and a photoconductive member for electrophotography is manufactured, any photoconductive member for electrophotography may be used. , high-quality images with significantly reduced image defects can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic side cross-sectional view of a deposited film forming apparatus using the μW-PCVD method, and FIG. 2 is a plan cross-sectional view of the apparatus. FIG. 3 is an explanatory diagram for schematically explaining the entire apparatus. FIG. 4 is a schematic structural explanatory diagram of a deposited film forming apparatus using an RF power source. FIG. 5 is an explanatory diagram for explaining an example of a deposited film forming process by μW-PCVD method and a cleaning process using ClF5 gas in the reaction vessel. In the figure, 101, 201, 301, 401... reaction vessel 102
．． 202...Microwave introduction window 103.303...
Waveguide 104, 204, 304... Exhaust pipe 105, 205... Cylindrical base 206, 206... Discharge area 107, 207... Substrate holder 107', 403... Heater 110... Motor 308...Gas introduction pipe 310...Raw material gas supply device 311...Microwave power source 312...Isolator 313...Power monitor 314...Stub tuner 315...Exhaust pump 402...・Substrate 404... High frequency power supply 405... Raw material gas supply system 407... Exhaust system 408... High frequency electrode

Claims (1)

[Claims] 1. A method for cleaning a deposited film forming apparatus that forms a deposited film, which includes removing reaction products adhering to a reaction vessel by forming a deposited film using ClF_3 gas. A method for cleaning a deposited film forming apparatus characterized by: 2. The method of cleaning a deposited film forming apparatus according to claim 1, wherein the cleaning is performed while supplying discharge energy. 3. The method for cleaning a deposited film forming apparatus according to claim 1, wherein the deposited film is a deposited film containing silicon. 4. The method for cleaning a deposited film forming apparatus according to claim 1, wherein the deposited film is used for a photoconductive member for electrophotography. 5. The material of the reaction vessel is aluminum alloy, nickel alloy, SS41 steel, SUS304, SUS316.
2. The method for cleaning a deposited film forming apparatus according to claim 1, wherein the cleaning material is selected from among , SUS430, and quartz glass. 6. A method for cleaning a deposited film forming apparatus that forms a deposited film, including the step of introducing the deposited film forming gas into a circulation space in the deposited film forming apparatus through which the deposited film forming gas can flow; A step of stopping the introduction of Cl
A method for cleaning a deposited film forming apparatus, comprising the step of introducing F_3 gas into the circulation space. 7. The method for cleaning a deposited film forming apparatus according to claim 6, wherein the step of introducing the deposited film forming gas, the stopping step, and the ClF_3 gas introducing step are repeated multiple times in this order.