JP2005101583A - Cleaning method of deposition system and deposition system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning method of a deposition system that prevents a constituent of the deposition system from being damaged, and removes a silicon base deposit in the deposition system. <P>SOLUTION: The cleaning method of a deposition system for removing at least a portion of the silicon nitride deposit deposited on the constituent of the deposition system after using it for depositing a thin film includes: a step for introducing first gas (12) including fluorine gas, and second gas (13) including nitrogen monoxide gas into the deposition system (11); and a step for heating the constituent. The constituent is formed of quartz or silicon carbide, and the silicon nitride deposit includes silicon nitride. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a film forming apparatus cleaning method and a film forming apparatus including a cleaning system.

  In manufacturing a semiconductor device, various (insulator) thin films such as a silicon dioxide film and a silicon nitride film are formed on a semiconductor wafer by using a film forming apparatus having a chemical vapor deposition reaction chamber (CVD reaction chamber). Has been done. In forming this thin film, the CVD reaction product is deposited not only on the target semiconductor wafer but also on components of the film forming apparatus, for example, a wall of the CVD reaction chamber, a semiconductor wafer mounting boat or a susceptor. If this deposited CVD reaction product is not removed, it will be peeled off from the inner wall of the CVD reaction chamber, etc., causing generation of particles, and the quality of the semiconductor thin film formed on the semiconductor wafer by the CVD reaction in a later step. Deteriorate. Therefore, it is necessary to clean the film forming apparatus.

  For example, in a low pressure (LP) CVD apparatus, normally, the apparatus is opened to the atmosphere and cleaning is performed by washing with an acid solution. However, in this case, since the steps of disassembling, cleaning, assembling, and leak checking are performed after the film forming apparatus is temporarily stopped, the time required for the work is long, and there is a problem from the viewpoint of productivity.

An LPCVD apparatus that can perform cleaning using reactive plasma without opening the film forming apparatus is also commercially available. In this case, NF ₃ , CF ₄ or the like is used as a reaction gas. From the viewpoint of reducing specific CFCs, a cleaning method is also disclosed in which FNO or F ₃ NO is used as a plasma generating gas to remove silicon-containing compounds deposited on stainless steel, aluminum, or an alloy thereof (see Patent Document 1). ). However, this plasma cleaning method requires an expensive plasma apparatus only for cleaning, although it is not used in the CVD process. In addition, since active chemical species generated by plasma are usually highly corrosive and have a short lifetime, there are many cases where special treatment is required for the inner wall of the apparatus, which is problematic in terms of apparatus cost.

Furthermore, in the LPCVD apparatus, it has been proposed to clean the inside of the CVD reaction chamber by a thermal reaction using a reactive gas. As the reactive gas, a fluorine-containing gas such as ClF ₃ , NF ₃ , HF, fluorine gas alone or a mixed gas thereof is used. Cleaning with these reactive gases damages the CVD reaction chamber, typically made of quartz. In particular, in the cleaning of silicon nitride, the etching rate of the object to be cleaned (silicon nitride) and the etching rate of quartz are almost the same, so the lifetime of the CVD chamber is greatly shortened, and high maintenance costs become a problem.

In order to solve these problems, Patent Document 2 discloses a method of cleaning silicon nitride by thermal reaction using a mixture of ClF ₃ and nitric oxide gas, but ClF ₃ is an expensive gas. There is a problem that the cost of cleaning becomes high.
International Publication WO 02/25713 JP 2000-77391 A

  Therefore, an object of the present invention is to provide a film forming apparatus cleaning method and a film forming apparatus capable of suppressing damage to the constituent members of the film forming apparatus and removing silicon deposits inside the film forming apparatus. To do.

  According to one aspect of the present invention, there is provided a film forming apparatus cleaning method for removing at least a part of a silicon-based deposit deposited on a constituent member of a film forming apparatus used for forming a thin film. Introducing a first gas containing fluorine gas and a second gas containing nitric oxide gas into the film forming apparatus, and heating the component member, the component member is quartz or There is provided a cleaning method for a film forming apparatus, characterized in that the film is formed of silicon carbide and the silicon-based deposit contains silicon nitride.

  According to another aspect of the present invention, there is provided a film forming apparatus for forming a silicon nitride film on a wafer in a reaction chamber, wherein a first gas containing fluorine gas is introduced into the reaction chamber. There is provided a film forming apparatus comprising: a gas introduction system; and a second gas introduction system for introducing a second gas containing nitrogen monoxide gas into the reaction chamber.

  ADVANTAGE OF THE INVENTION According to this invention, the damage to the structural member of a film-forming apparatus can be suppressed, and the silicon-type deposit inside a film-forming apparatus can be removed.

  Hereinafter, various aspects of the present invention will be described in more detail.

In one aspect, the present invention relates to a cleaning method for removing at least a part of a silicon-based deposit deposited on a constituent member of a film forming apparatus by introducing a cleaning gas into the film forming apparatus. A gas mixture including a first gas containing fluorine (F ₂ ) gas and a _second gas containing nitrogen monoxide (NO) gas is used.

  In one embodiment, when cleaning and removing silicon deposits deposited in the film forming apparatus, first, the film forming apparatus that has completed the normal silicon film forming process is evacuated.

  The film forming apparatus includes, for example, a CVD reaction chamber. Further, in the film forming apparatus, a mounting member (for example, in the case of a batch type film forming apparatus, a boat, and in the case of a single wafer type film forming apparatus) on which a semiconductor wafer to be subjected to predetermined film forming is placed. Is a susceptor). The constituent members of the film forming apparatus include a CVD reaction chamber and a semiconductor wafer mounting member. The CVD reaction chamber walls are typically made of quartz. The mounting member of the semiconductor wafer is usually formed of quartz, silicon carbide (SiC), or a carbon material whose surface is coated with silicon carbide. A film forming apparatus according to one aspect of the present invention is for forming a silicon nitride film as a silicon-based thin film. In one aspect of the present invention, a silicon nitride deposit on a quartz member or a silicon carbide member. Is removed by cleaning. In addition, the film forming apparatus usually includes a CVD source gas introduction pipe and an exhaust pipe. These pipes are usually made of quartz or stainless steel. Needless to say, the film forming apparatus includes a fluorine gas introduction pipe and a nitric oxide gas introduction pipe.

  After exhausting the film forming apparatus, the constituent members of the film forming apparatus are heated. In the case of a batch type film forming apparatus, the CVD reaction chamber is heated by a heater provided around the CVD reaction chamber. At that time, the semiconductor wafer mounting boat provided in the CVD reaction chamber is also heated at the same time. In the case of a single wafer deposition apparatus, the susceptor is heated by a heater provided inside the susceptor. Even in the case of a single wafer type film forming apparatus, a heater can be provided around the CVD reaction chamber, and the CVD reaction chamber can be heated by the heater.

  After the constituent members of the film forming apparatus are heated in this manner, a first gas containing fluorine gas and a second gas containing nitrogen monoxide gas are introduced into the CVD reaction chamber. At that time, an inert diluent gas can be introduced. As the inert diluent gas, a rare gas such as argon, nitrogen, or the like can be used.

  When cleaning with the first gas (fluorine gas) and the second gas (nitrogen monoxide gas), the inside of the CVD reaction chamber can be maintained under a pressure of 0.1 Torr to 760 Torr.

At the time of cleaning, the flow rate ratio (F ₂ / NO flow rate ratio) of the second gas (nitrogen monoxide gas) to the first gas (fluorine gas) is the etching selectivity of the silicon nitride deposit with respect to the constituent members of the film forming apparatus. In view of the above, it is usually introduced into the CVD reaction chamber in a range of 0.01 or more and less than 2. When the F ₂ / NO flow rate ratio is 2 or more, not only the selection ratio decreases but also the etching rate of the silicon-based deposit tends to become extremely slow. That is, by setting the F ₂ / NO flow rate ratio R in the range of 0.01 ≦ R <2, the etching rate of the silicon nitride deposit is significantly increased, and the etching rate for the constituent members of the film forming apparatus is increased. The selectivity is also improved.

  In general, this cleaning can be performed at a temperature from room temperature to 1000 ° C. However, at a high temperature of 400 ° C. or higher, or a low temperature of 100 ° C. or lower, the difference in etching rate between the silicon nitride deposit to be cleaned and the constituent member tends to decrease. Accordingly, in one aspect, the cleaning is performed at a temperature of 100 ° C to 400 ° C. By performing the cleaning at a temperature within the range of 100 ° C. to 400 ° C., the maximum etching rate selection ratio can be obtained under the second gas / first gas flow ratio condition set at that time. In another embodiment, the cleaning temperature is around 200 ° C. Note that, at a temperature exceeding 400 ° C., the etching rate of the silicon nitride deposit by the first gas and the second gas is fast, so first, at a temperature exceeding 400 ° C. to the vicinity of the interface with the constituent members of the film forming apparatus, The cleaning can be performed, and then the temperature can be lowered stepwise or continuously, and the cleaning can be terminated at a temperature of 100 ° C. to 400 ° C. (preferably around 200 ° C.) at which a high etching rate selection ratio can be obtained. The cleaning of the silicon nitride deposit up to the vicinity of the interface with the constituent member is controlled by the cleaning time if the thickness of the silicon nitride deposit and the etching rate of the silicon nitride deposit by the cleaning gas used are measured in advance. be able to.

As is clear from the above description, in order to clean the silicon nitride deposit at a high speed without significantly damaging the components of the film forming apparatus, the cleaning temperature is set in the range of 100 ° C. to 400 ° C. , F ₂ / NO flow rate ratio R can be set in a range of 0.01 ≦ R <2.

  The second gas (nitrogen monoxide gas) increases the etching rate of the silicon nitride deposit, but does not significantly damage the constituent members of the film forming apparatus, so that the damage to the constituent members of the film forming apparatus is minimized. The silicon nitride deposit can be selectively removed by cleaning with a limited amount.

  By the way, fluorine gas (first gas) can be synthesized on site, and the synthesized fluorine gas can be temporarily stored or directly introduced into the CVD reaction chamber. Fluorine gas cannot be filled into the cylinder at high pressure due to safety issues. Therefore, supply from the cylinder should be cleaned for a long time, or multiple film deposition systems should be cleaned in parallel. Is difficult. The difficulty can be avoided by synthesizing fluorine gas in the field. For the synthesis of fluorine gas, a method of electrolysis of HF is used. Fluorine gas supply volume that is limited by cylinder volume, such as cylinder-filled fluorine gas, by using a system (on-site manufacturing system) that generates fluorine gas on site by HF electrolysis and supplies it to the CVD reaction chamber Without this problem, it becomes possible to perform cleaning for a long time or to perform cleaning of a plurality of apparatuses in parallel. In addition, the manufacturing machine of the fluorine gas by electrolysis of HF is marketed.

  Needless to say, the cleaning is not performed after every single film formation of the silicon nitride thin film, and is usually nitrided with a thickness that is unacceptable to components such as the inner wall of the CVD reaction chamber by several film formations. After the silicon deposit is deposited.

  By the way, as described above, the piping of the film forming apparatus may be formed of stainless steel. Here, when exposed to fluorine gas and nitric oxide gas at the same time, the life of the stainless steel pipe whose inner surface is coated with nickel, aluminum or alumina is significantly longer than the life of any uncoated stainless steel. It turned out that (especially exhaust piping). This extended life can also be obtained by making such a pipe itself from aluminum or alumina. Stainless steel exhibits a unique behavior in that it is more reactive with a mixture of fluorine gas and nitrogen monoxide gas than with a fluorine-containing gas alone or a mixed gas of fluorine gas and hydrogen fluoride gas.

  FIG. 1 is a block diagram showing an example of a film forming apparatus provided with a cleaning system according to one embodiment of the present invention. This film forming apparatus is of a type in which a first gas (fluorine gas) and a second gas (nitrogen monoxide gas) are separately introduced into a CVD reaction chamber.

  A film forming apparatus 10 shown in FIG. 1 includes a CVD reaction chamber 11, a first gas (fluorine gas) supply source 12, a second gas (nitrogen monoxide gas) supply source 13, and a non-introduced system. An active dilution gas source 14 is provided.

  The CVD reaction chamber 11 is composed of, for example, a quartz reaction furnace, and a process tube 111 made of, for example, quartz is disposed therein. In the process tube 111, for example, a semiconductor substrate support base 112 made of stainless steel and a pair of quartz rods 113a and 113b provided with a plurality of grooves for inserting and holding a semiconductor substrate (not shown) are installed. . The pair of quartz rods 113a and 113b constitute a so-called boat. A heater 114 is provided around the CVD reaction chamber 11. After the formation of the silicon thin film is completed, the semiconductor substrate is removed from the boat (113a, 113b). The CVD reaction chamber 11 is heated to a predetermined temperature by the heater 114.

  The fluorine gas that is the first gas is introduced from the supply source 12 (for example, a cylinder) into the CVD reaction chamber 11 through the fluorine gas supply line L11. The line L11 is provided with an on-off valve V11, and a flow rate regulator such as a mass flow controller MFC11 is provided downstream thereof. The fluorine gas is adjusted to a predetermined flow rate by the mass flow controller MFC 11 and introduced into the CVD reaction chamber 11.

  The second gas, which is nitrogen monoxide gas, is introduced from the supply source 13 (for example, a cylinder) into the CVD reaction chamber 11 through the second gas supply line L12. The line L12 is provided with an on-off valve V12 and a flow rate regulator, for example, a mass flow controller MFC12 downstream. The second gas is adjusted to a predetermined flow rate by the mass flow controller MFC 12 and introduced into the CVD reaction chamber 11.

  The inert dilution gas is introduced into the CVD reaction chamber 11 from the supply source 14 (for example, a cylinder) through the inert dilution gas supply line L13 as necessary. The line L13 is provided with an on-off valve V13 and a flow regulator, for example, a mass flow controller MFC13 downstream. The inert dilution gas is adjusted to a predetermined flow rate by the mass flow controller MFC 13 and introduced into the CVD reaction chamber 11.

  The outlet of the CVD reaction chamber 11 is connected to the waste gas treatment device 15 by a line L14. The waste gas treatment device 15 removes by-products and unreacted substances, and the gas treated by the waste gas treatment device 15 is discharged out of the system. A pressure sensor PG, a pressure regulator such as a butterfly valve BV1, and a vacuum pump PM are connected to the line L14. The pressure in the CVD reaction chamber 11 is monitored by the pressure sensor PG, and is set to a predetermined pressure value by opening / closing control of the butterfly valve BV1.

  Needless to say, the CVD reaction chamber 11 is connected to a CVD source gas supply system (not shown) for performing a normal CVD reaction (film formation of a silicon nitride thin film).

  In the apparatus of FIG. 1, for example, after a silicon nitride film is formed on a semiconductor substrate, silicon nitride deposits deposited on the inner wall of the CVD reaction chamber 11, the inner and outer surfaces of the process tube 111, the quartz rods 113a and 113b, and the like. Can be removed by cleaning according to the present invention.

  FIG. 2 is a type in which a first gas and a second gas are mixed in advance and then introduced into a CVD reaction chamber, and has the same configuration as the film forming apparatus of FIG. 2, the same components as those in the film forming apparatus in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the film forming apparatus shown in FIG. 2, the second gas supply line L12 merges with the first gas supply line L11 on the upstream side of the semiconductor chamber 11, and the merged line merges with the inert dilution gas supply line L13. ing. According to this arrangement, the inert dilution gas can be introduced into the CVD reaction chamber 11 in advance in a state of being mixed with the first gas and the second gas.

  FIG. 3 shows a film forming apparatus 20 similar to the film forming apparatus 10 shown in FIG. 2, except that a fluorine gas on-site manufacturing system is provided. 3, the same components as those in the film forming apparatus in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  A film forming apparatus 20 shown in FIG. 3 is a fluorine gas that produces fluorine gas by electrolysis of a hydrogen fluoride (HF) gas supply source 21 and HF instead of the fluorine gas supply source 12 in the film forming apparatus of FIG. A manufacturing machine 22 is provided. The HF gas is introduced from the supply source 21 into the fluorine gas production machine 22 through the HF gas supply line L21. The HF gas supply line L21 is provided with an on-off valve V21. A buffer tank (not shown) for temporarily storing the produced fluorine gas may be provided downstream of the fluorine gas production machine 22. The produced fluorine gas is introduced into the CVD reaction chamber 11 through the fluorine gas supply line L22 together with the second gas and, if necessary, an inert dilution gas. The line L22 is provided with an on-off valve V22 and a flow rate regulator such as a mass flow controller MFC11 downstream thereof. The fluorine gas is adjusted to a predetermined flow rate by the mass flow controller MFC 11 and introduced into the CVD reaction chamber 11.

  FIG. 3 shows a system in which the fluorine gas and the second gas are mixed in advance and then introduced into the CVD reaction chamber. However, the fluorine gas and the second gas are converted into the apparatus shown in FIG. Alternatively, they may be introduced separately into the CVD reaction chamber.

  Although FIGS. 1 to 3 described above show the batch type film forming apparatus, it is needless to say that the present invention can be applied to a single wafer type film forming apparatus as described above. .

  Thus, according to the present invention, silicon nitride deposits on quartz or silicon carbide can be selectively cleaned away.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.

Example 1
Fluorine gas and nitrogen monoxide gas were introduced into a CVD reaction chamber containing a silicon nitride deposited sample and a quartz sample, and cleaning was performed under the following conditions.

Fluorine gas flow rate: 500sccm
Nitric oxide gas flow rate: 200sccm
Nitrogen gas flow rate: 300sccm
CVD reaction chamber pressure: 50 Torr
Cleaning temperature: 200 ° C.

  As a result, the etching rate of silicon nitride was 3500 Å / min, and the etching rate of quartz was 220 Å / min. In this example, the etching ratio of the silicon nitride film to the quartz is about 16, indicating that the silicon nitride cleaning is selectively achieved.

Example 2
Fluorine gas and nitrogen monoxide gas are introduced into the CVD reaction chamber containing the silicon nitride deposited sample and the quartz sample, the pressure inside the CVD reaction chamber is set to 50 Torr, and the fluorine gas flow rate and the total gas flow rate are set respectively. Cleaning was performed at 500 sccm and 1000 sccm. At that time, the cleaning temperature was changed within a range of 100 ° C. to 600 ° C. The flow rate of nitric oxide gas was also changed in the range of 100 sccm to 200 sccm. The amount of less than 1000 sccm at the total gas flow rate was supplemented with nitrogen gas. The results are shown in FIG. In FIG. 4, line a shows the results when the NO / F ₂ flow ratio is 0.2, and line b shows the results when the NO / F ₂ flow ratio is 0.4.

From the results shown in FIG. 4, the maximum etching rate selection ratio (silicon nitride (shown as SiN in FIG. 4) / quartz) at each NO / F ₂ flow rate ratio is obtained in the cleaning temperature range of 100 ° C. to 400 ° C. I understand that

Example 3
Fluorine gas and nitric oxide gas are introduced into the CVD reaction chamber containing the silicon nitride deposited sample and the quartz sample, the CVD reaction chamber pressure is set to 50 Torr, the cleaning temperature is set to 200 ° C., Cleaning was performed by setting the nitrogen oxide gas flow rate and the total gas flow rate to 200 sccm and 1000 sccm, respectively. At that time, the flow rate of the fluorine gas was changed within the range of 100 sccm to 500 sccm. The amount of less than 1000 sccm at the total gas flow rate was supplemented with nitrogen gas. The results are shown in FIG. In FIG. 5, the shaded bar graph indicates the etching rate of silicon nitride, the open bar graph indicates the etching rate of quartz, and the line a indicates the etching selectivity (silicon nitride / quartz).

  From the results shown in FIG. 5, it can be seen that as the nitrogen monoxide gas / fluorine gas flow rate ratio approaches 2, the etching rate and the etching selectivity ratio decrease. It can be seen that the nitric oxide gas / fluorine gas flow ratio must be less than 2 to clean the silicon nitride deposit faster than the quartz member.

Example 4
Fluorine gas and nitrogen monoxide gas were introduced into the CVD reaction chamber containing the silicon nitride deposited sample and the quartz sample, the CVD reaction chamber pressure was set to 50 Torr, and the cleaning temperature was set to 200 ° C. At that time, the flow rate of fluorine gas was set to 500 sccm, and the flow rate of nitric oxide gas was changed in the range of 0 sccm to 200 sccm. In order to keep the total gas flow rate at 1000 sccm, the insufficient gas flow rate was supplemented with nitrogen gas. FIG. 6 shows the result of the etching rate, and FIG. 7 shows the result of the selectivity of the etching rate of silicon nitride with respect to quartz. In FIG. 6, line a shows the results for quartz and line b shows the results for silicon nitride.

  From the results shown in FIG. 6, it can be seen that by adding nitric oxide gas, the etching rate of silicon nitride can be increased while keeping the etching rate of quartz constant. Furthermore, it can be seen that the etching rate of silicon nitride tends to saturate with respect to the amount of nitric oxide gas added, and the effect appears when the nitric oxide gas / fluorine gas flow ratio is 0.01 or more. Furthermore, from the results shown in FIG. 7, it is found that the etching rate of silicon nitride (shown as SiN in FIG. 7) is higher than the etching rate of quartz when the flow rate ratio of nitric oxide gas / fluorine gas is 0.01 or more. Understand.

Example 5
In a CVD reaction chamber containing a silicon nitride deposited sample, a quartz sample, and a silicon carbide sample, fluorine gas, a second gas (nitrogen monoxide gas), and nitrogen gas are supplied at a flow ratio of 50/1/49. The etching rate of each sample was measured at a temperature of 300 ° C. while maintaining the pressure in the reaction chamber at 50 Torr. The results are shown below.

Silicon carbide etching rate: 50 Å / min Quartz etching rate: 90 Å / min Silicon nitride etching rate: 380 Å / min.

  For comparison, without adding the second gas (nitrogen monoxide gas), fluorine gas and nitrogen gas were supplied at a flow rate ratio of 50/50, and the pressure in the reaction chamber was maintained at 50 Torr. The results of measuring the etching rate of each sample are shown below.

Silicon carbide etching rate: 6 Å / min Quartz etching rate: 14 Å / min Silicon nitride etching rate: 0 Å / min.

  From this result, it is proved that silicon nitride deposited on a component made of silicon carbide or silicon oxide (quartz) can be cleaned and removed with a high selectivity by using fluorine gas and nitrogen monoxide gas as the cleaning gas. It was done.

Example 6
In a reaction chamber, under a pressure of 760 Torr, a stainless steel SS-316L specimen and a nickel specimen were mixed at 200 ° C. with a mixture of fluorine gas and hydrogen fluoride gas (F ₂ / HF volume ratio = 50/50) or fluorine gas, respectively. And a mixture of nitrogen monoxide gas (F ₂ / NO volume ratio = 50/50) were exposed for a predetermined time. From the surface of the test piece after the exposure, the penetration depth of fluorine was obtained by Auger electron spectroscopy, and the reaction rate (mm / year) of each test piece by each mixed gas was calculated from the obtained depth and the exposure time. The results are shown in Table 1 below.

  From the results shown in Table 1, stainless steel is more reactive with a mixed gas of fluorine gas and nitrogen monoxide gas than with a mixed gas of fluorine gas and hydrogen fluoride gas. It turns out that it hardly reacts with the mixed gas with nitric oxide gas.

  As described above, according to the method of the present invention, it is possible to suppress the damage to the constituent members of the film forming apparatus and to clean the silicon nitride deposit in a high speed and in a short time. In particular, by setting the cleaning temperature in the range from 100 ° C. to 400 ° C., the maximum selection ratio can be obtained under the flow rate conditions set at that time. In addition, the second gas / first gas flow rate ratio greatly affects the selection ratio and the etching rate. By setting the flow rate ratio in a range from 0.01 to less than 2, the selection ratio is particularly high and the high speed is high. Cleaning of the silicon nitride deposit can be realized.

FIG. 3 is a block diagram illustrating an example of a film forming apparatus including a cleaning system. The block diagram which shows the other example of the film-forming apparatus provided with the cleaning system. The block diagram which shows the further another example of the film-forming apparatus provided with the cleaning system. The graph which shows the temperature dependence of the etching selection ratio with respect to quartz of silicon nitride. The graph which shows the nitric oxide / fluorine gas flow ratio dependence of the etching rate and selection ratio of silicon nitride and quartz. The graph which shows the nitric oxide / fluorine gas flow ratio dependence of the etching rate of silicon nitride and quartz. The graph which shows the nitric oxide / fluorine gas flow ratio dependence of the etching selection ratio with respect to quartz of silicon nitride.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,20 ... Film-forming apparatus provided with cleaning system, 11 ... CVD reaction chamber, 12 ... First gas supply source, 13 ... Second gas supply source, 14 ... Inert gas supply source, 15 ... Waste gas treatment Equipment: 21 ... Hydrogen fluoride gas supply source, 22 ... Fluorine gas production machine, 111 ... Process tube, 112 ... Semiconductor substrate support base, 113a, 113b ... Semiconductor substrate support rod (boat), 114 ... Heater, L11 to L14 L21, L22 ... Gas supply line, V11-V13, V21-V22 ... Open / close valve, PG ... Pressure sensor, MFC11-MFC13 ... Mass flow controller, BV1 ... Butterfly valve, PM ... Vacuum

Claims (11)

  A cleaning method for a film forming apparatus for removing at least a part of silicon-based deposits deposited on constituent members of a film forming apparatus after being used for forming a thin film, wherein fluorine gas is introduced into the film forming apparatus. Including introducing a first gas containing and a second gas containing nitric oxide gas, and heating the component, wherein the component is formed of quartz or silicon carbide, and the silicon-based A method for cleaning a film forming apparatus, wherein the deposit contains silicon nitride.   The cleaning method according to claim 1, wherein a flow rate ratio of the second gas to the first gas introduced into the film forming apparatus is set in a range of 0.01 or more and less than 2.   The cleaning method according to claim 1, wherein the component member is heated to a temperature of 100 ° C. to 400 ° C. 3.   The cleaning method according to claim 1, wherein the first gas is supplied from an electrolysis apparatus for hydrogen fluoride attached to the film forming apparatus.   The cleaning method according to claim 1, wherein the film forming apparatus includes a pipe made of stainless steel, and an inner surface of the pipe is coated with nickel, aluminum, or alumina. .   The cleaning method according to claim 1, wherein the film forming apparatus includes a pipe made of nickel or aluminum.   The constituent member is heated to a temperature exceeding 400 ° C. to remove the silicon deposit to the vicinity of the interface with the constituent member, and then the temperature is lowered to complete the cleaning at a temperature from 100 ° C. to 400 ° C. The cleaning method according to claim 1, wherein the cleaning is performed.   A film forming apparatus for forming a silicon nitride film on a wafer in a reaction chamber, the first gas introducing system for introducing a first gas containing fluorine gas into the reaction chamber, and a first gas comprising nitrogen monoxide. And a second gas introduction system for introducing the second gas into the reaction chamber. The film forming apparatus according to claim 8, further comprising an electrolysis apparatus for hydrogen fluoride that supplies the first gas. The film forming apparatus according to claim 8 or 9, wherein the film forming apparatus includes a pipe made of stainless steel, and an inner surface of the pipe is coated with nickel, aluminum, or alumina.   The film forming apparatus according to claim 8, wherein the film forming apparatus includes a pipe made of nickel or aluminum.

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