JP4423282B2 - Manufacturing method of semiconductor device - Google Patents

Description

  The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device including a manufacturing process of a silicon nitride film by a thermal CVD (Chemical Vapor Deposition) method.

Conventionally, a silicon nitride film used for a semiconductor device is generally formed by a mixed gas of SiH ₂ Cl ₂ (hereinafter referred to as DCS) and NH ₃ .

However, in this method, it is necessary to form a silicon nitride film at a high temperature of 700 ° C. to 800 ° C. As a result, impurities in the shallow diffusion layer diffuse deeply due to heat, and the element size cannot be reduced. is there. Further, NH ₄ Cl (ammonium chloride), which is a reaction by-product, adheres to the exhaust port, and this NH ₄ Cl causes rust on the metal surface and causes metal contamination on the semiconductor wafer. .

In order to solve these problems, the present inventors used SiH ₂ (NH (C ₄ H ₉ )) ₂ (Bistal butyl amino silane) and NH ₃ as source gas. It was considered to form a silicon nitride (Si ₃ N ₄ ) film. As a result, it has been found that a silicon nitride film can be formed at a low temperature of about 600 ° C. and NH ₄ Cl that causes metal contamination is not generated.

However, the present inventors have found that the Si ₃ N ₄ film using BTBAS has the following drawbacks.

That is, BTBAS and NH ₃ introduced into the furnace are thermally decomposed, and an Si ₃ N ₄ film is formed not only on the wafer but also on the quartz reaction tube inner wall and the quartz inside the reaction tube. The Si ₃ N ₄ film using Si has the property of high film stress and large film shrinkage. Comparison data of a general DCS and NH ₃ with a Si ₃ N ₄ film are shown in FIG. 4 for the film shrinkage rate and in FIG. 5 for the film stress. In FIG. 4, 5, B shows the case of _{the Si} 3 _{N 4} film by BTBAS and NH _3, D shows the case of _{the Si} 3 _{N 4} film by the DCS and NH _3. The film stress is a pulling force (film stress), and the Si ₃ N ₄ film formed on the reactor quartz is peeled off by the film stress. Further, the film shrinks due to the temperature of the reactor (about 600 ° C.). Quartz does not shrink or expand due to heat, and therefore distortion occurs. Therefore, when the Si ₃ N ₄ film on the quartz becomes thick, microcracks are generated in the quartz and particles are generated on the wafer. The Si ₃ N ₄ film thickness that causes microcracks is 4000 mm.

In order to solve this particle problem, the quartz inner tube 12, the quartz boat 14, and the quartz cap 15 in the vertical LPCVD deposition apparatus 1 shown in FIG. Therefore, it is necessary to perform maintenance by a method of performing wet cleaning using an Si and removing the Si ₃ N ₄ film. If one film formation is 1000 mm, maintenance is required every four film formations. In addition, the time required for maintenance is 16 hours, and there is a problem that it takes too much time.

Therefore, the main object of the present invention is to solve the problem of high maintenance frequency when manufacturing Si ₃ N ₄ film with BTBAS and NH _3, and to reduce the maintenance frequency as much as possible and to suppress the generation of particles. Another object is to provide a method for manufacturing a semiconductor device that can be prevented.

According to the present invention,
The temperature of the reaction vessel made of quartz while maintaining the 600 ° C. or less, inserting the Bicester-tert-butyl amino silane and NH ₃ flowing into the reaction vessel as a source gas, a silicon nitride film into the reaction vessel Forming on the film-formed body,
By flowing NF ₃ gas as a cleaning gas into the reaction vessel, and a step of removing the silicon nitride which is formed in the reaction vessel,
In the step of removing the silicon nitride, the silicon nitride formed in the reaction vessel is peeled off due to film stress, or before the film thickness becomes such that microcracks are generated in the quartz due to film shrinkage. A method for manufacturing a semiconductor device is provided, which is performed in a state where the pressure in the reaction vessel is maintained at 10 Torr or higher and the temperature is maintained at 600 ° C.

Moreover, according to the present invention,
With the temperature inside the reaction vessel made of quartz maintained at 600 ° C., bismutual butylamino silane and NH ₃ And flowing into the reaction vessel as a source gas to form a silicon nitride film on the deposition target inserted in the reaction vessel;
NF as a cleaning gas in the reaction vessel ₃ Flowing a gas to remove silicon nitride formed in the reaction vessel,
In the step of removing the silicon nitride, the silicon nitride formed in the reaction vessel is peeled off due to film stress, or before the film thickness becomes such that microcracks are generated in the quartz due to film shrinkage. A method for manufacturing a semiconductor device is provided, which is performed in a state where the pressure in the reaction vessel is kept at 10 to 70 Torr and the temperature is kept at 600 ° C.

Moreover, according to the present invention,
Inserting a boat holding the film formation body into a reaction vessel made of quartz ;
In the state where the temperature in the reaction vessel is kept at 600 ° C. or less, the butylaminosilane and NH ₃ are flowed as raw material gases into the reaction vessel, and the deposition material held by the boat in the reaction vessel. Forming a silicon nitride film on the film body;
A step of pulling out the boat holding the film formation target after the formation of the silicon nitride film from the reaction vessel;
Inserting the boat that does not hold the deposition target in the reaction vessel;
Flowing NF ₃ gas as a cleaning gas into the reaction vessel in which the boat not holding the film formation body is inserted to remove silicon nitride formed in the reaction vessel and the boat;
Withdrawing the boat that does not hold the film formation body from the reaction vessel, and
In the step of removing the silicon nitride, the silicon nitride formed in the reaction vessel is peeled off due to film stress, or before the film thickness becomes such that microcracks are generated in the quartz due to film shrinkage. A method for manufacturing a semiconductor device is provided, which is performed in a state where the pressure in the reaction vessel is maintained at 10 Torr or higher and the temperature is maintained at 600 ° C.

Moreover, according to the present invention,
Inserting a boat holding the film formation body into a reaction vessel made of quartz;
While keeping the temperature of the reaction vessel 600 ° C., said to the reaction vessel and Bicester-tert-butyl amino silane and NH ₃ to flow in the raw material gas, the object held by the boat in the reaction vessel Forming a silicon nitride film on the film-forming body;
A step of pulling out the boat holding the film formation target after the formation of the silicon nitride film from the reaction vessel;
Inserting the boat that does not hold the deposition target in the reaction vessel;
Flowing NF ₃ gas as a cleaning gas into the reaction vessel in which the boat not holding the film formation body is inserted to remove silicon nitride formed in the reaction vessel and the boat ;
Withdrawing the boat that does not hold the film formation body from the reaction vessel, and
Removing the silicon nitride, silicon nitride is formed in the reaction vessel, or peeled off by the film stress, or, prior to a thickness of microcracks generated in the quartz by film contraction, the A method for manufacturing a semiconductor device is provided, which is performed in a state where the pressure in the reaction vessel is maintained at 10 to 70 Torr and the temperature is maintained at 600 ° C.

  Preferably, the film stress of the silicon nitride is at least 2 GPa.

Preferably, in the step of removing the silicon nitride, NF ₃ gas is supplied into the reaction vessel at a flow rate of 500 sccm.

Moreover, according to the present invention,
Inserting a boat made of quartz holding a film formation body into a reaction vessel made of quartz;
In a state where the temperature in the reaction vessel is kept at 600 ° C. or less, the reaction vessel is filled with Vista-butylaminosilane and NH. ₃ And forming a silicon nitride film on the film formation body held by the boat in the reaction vessel,
A step of pulling out the boat holding the film formation target after the formation of the silicon nitride film from the reaction vessel;
Inserting the boat that does not hold the deposition target in the reaction vessel;
NF as a cleaning gas in the reaction vessel in which the boat not holding the film formation body is inserted ₃ Flowing gas to remove silicon nitride formed in the reaction vessel and the boat;
Withdrawing the boat that does not hold the film formation body from the reaction vessel, and
The step of removing the silicon nitride is performed before the silicon nitride formed in the reaction vessel or the boat is peeled off due to film stress or becomes a film thickness that causes microcracking in the quartz due to film shrinkage. In addition, there is provided a method for manufacturing a semiconductor device, which is performed in a state where the pressure in the reaction vessel is maintained at 10 Torr or higher and the temperature is maintained at 600 ° C.

Preferably, the silicon nitride film stress using bis-tertiary butylamino silane and NH ₃ as source gases is a silicon nitride film formed at 700 to 800 ° C. using SiH ₂ Cl ₂ and NH ₃ as source gases. About twice as much stress.

Moreover, according to the present invention,
Inserting a boat made of quartz holding a film formation body into a reaction vessel made of quartz;
In the state where the temperature in the reaction vessel is kept at 600 ° C., the film deposition film held by the boat in the reaction vessel by flowing the binary butyl aminosilane and NH ₃ as source gases in the reaction vessel. Forming a silicon nitride film on the body;
A step of pulling out the boat holding the film formation target after the formation of the silicon nitride film from the reaction vessel;
Inserting the boat that does not hold the deposition target in the reaction vessel;
Flowing NF ₃ gas as a cleaning gas into the reaction vessel in which the boat not holding the film formation body is inserted to remove silicon nitride formed in the reaction vessel and the boat;
Withdrawing the boat that does not hold the film formation body from the reaction vessel, and
The step of removing the silicon nitride is performed before the silicon nitride formed in the reaction vessel or the boat is peeled off due to film stress or becomes a film thickness that causes microcracking in the quartz due to film shrinkage. In addition, a method for manufacturing a semiconductor device is provided, which is performed in a state where the pressure in the reaction vessel is kept at 10 to 70 Torr and the temperature is kept at 600 ° C.

According to the present invention, when a Si ₃ N ₄ film is manufactured using BTBAS and NH ₃ , there is provided a method for manufacturing a semiconductor device capable of reducing the maintenance frequency as much as possible and suppressing or preventing the generation of particles.

  Next, an embodiment of the present invention will be described with reference to the drawings.

  Since BTBAS used in the present invention is a liquid at normal temperature, it is introduced into the furnace using a BTBAS supply apparatus as shown in FIGS.

  The BTBAS supply apparatus shown in FIG. 2 is a combination of a thermostatic bath and gas flow rate control. The BTBAS supply device shown in FIG. 3 performs flow rate control by a combination of liquid flow rate control and a vaporizer.

Referring to FIG. 2, in the BTBAS supply device 4, the inside of the thermostatic bath 41 provided with the BTBAS liquid raw material 42 is heated to about 100 ° C., and the BTBAS is vaporized by increasing the vapor pressure of BTBAS, and then vaporized. The flow rate of BTBAS is controlled by the mass flow controller 43 and supplied from the BTBAS supply port 44 to the supply port 22 of the nozzle 21 of the vertical LPCVD (low pressure CVD) film forming apparatus shown in FIG.
In the BTBAS supply device 4, the pipe from the BTBAS liquid raw material 42 to the BTBAS supply port 44 is covered with a pipe heating member 45.

Referring to FIG. 3, in the BTBAS supply device 5, the extruded gases He and N ₂ introduced from the extruded gas introduction port 53 are introduced into the BTBAS tank 51 including the BTBAS liquid raw material 52 through the pipe 54. As a result, the BTBAS liquid raw material 32 is pushed out to the pipe 55, and then the BTBAS liquid raw material is flow-controlled by the liquid flow rate control device 56 and sent to the vaporizer 57, and is vaporized by the vaporizer 57 and from the BTBAS supply port 58 as shown in FIG. Is supplied to the supply port 22 of the nozzle 21 of the vertical LPCVD (low pressure CVD) film forming apparatus shown in FIG. In the BTBAS supply device 5, the pipe from the vaporizer 57 to the BTBAS supply port 58 is covered with a pipe heating member 59.

  Next, a vertical LPCVD film forming apparatus that can be suitably used in this embodiment will be described with reference to FIG.

  The vertical LPCVD film forming apparatus 1 includes a heater 13 outside the quartz reaction tube 11 so that the inside of the quartz reaction tube 11 can be heated uniformly. A quartz inner tube 12 is provided in the quartz reaction tube 11. In the quartz inner tube 12, there is provided a quartz boat 14 on which a plurality of semiconductor wafers are stacked in the vertical direction. The quartz boat 14 is mounted on a cap 15, and is inserted into the quartz inner tube 12 and taken out from the quartz inner tube 12 by moving the cap 15 up and down. The lower part of the quartz reaction tube 11 and the quartz inner tube 12 has an open structure, but when the cap 15 is lifted, it is closed by the bottom plate 24 of the cap 15 and has an airtight structure. Quartz nozzles 18 and 21 are provided in communication with the lower part of the quartz inner tube 12. The upper part of the quartz inner tube 12 is open. In the lower part of the space between the quartz inner tube 12 and the quartz reaction tube 11, an exhaust port 17 is provided in communication. The exhaust port 17 communicates with a vacuum pump (not shown), and the inside of the quartz reaction tube 11 can be depressurized. The source gases supplied from the quartz nozzles 18 and 21 are ejected from the respective ejection ports 20 and 23 into the quartz inner tube 12, and then move from the lower part to the upper part in the quartz inner tube 12. It flows downward through the space between the quartz reaction tube 11 and is exhausted from the exhaust port 17.

  Next, a method for manufacturing a silicon nitride film using the vertical LPCVD film forming apparatus 1 will be described.

  First, the quartz boat 14 holding a large number of semiconductor wafers 16 is inserted into the quartz inner tube 12 maintained at a temperature of 600 ° C. or lower.

  Next, vacuum exhaust is performed from the exhaust port 17 using a vacuum pump (not shown). In order to obtain an in-plane temperature stabilization effect of the wafer, it is preferable to evacuate for about 1 hour.

Next, NH ₃ gas is injected from the inlet 19 of the quartz nozzle 18 and the inside of the quartz reaction tube 11 is purged with NH ₃ before BTBAS flows.

Next, NH ₃ gas is continuously injected from the injection port 19 of the quartz nozzle 18, and BTBAS is injected from the injection port 22 of the quartz nozzle 21 to form a Si ₃ N ₄ film on the semiconductor wafer 16.

Next, with the NH ₃ gas being injected from the injection port 19 of the quartz nozzle 18, the supply of BTBAS is stopped, and the inside of the quartz reaction tube 11 is purged with NH ₃ .

When only BTBAS is flowed, a film different from the Si ₃ N ₄ film is formed. Therefore, it is preferable to purge with NH ₃ before and after deposition.

Next, N ₂ is caused to flow into the quartz reaction tube 11 from the quartz nozzle 18 and N ₂ purge is performed to remove NH ₃ in the quartz reaction tube 11.

Thereafter, the supply of N ₂ is stopped and the quartz reaction tube 11 is evacuated. N ₂ purge and subsequent vacuum evacuation in the quartz reaction tube 11 are performed several times as a set.

  Thereafter, the inside of the quartz reaction tube 11 is returned from the vacuum state to the atmospheric pressure state, and then the quartz boat 14 is lowered and pulled out from the quartz reaction tube 11, and then the quartz boat 14 and the semiconductor wafer 16 are lowered to room temperature.

By repeating the silicon nitride film manufacturing method described above, when the Si ₃ N ₄ film thickness in the quartz reaction tube 11 reaches 3000 mm, NF ₃ gas is introduced into the quartz reaction tube 11 from the quartz nozzle 18. In situ cleaning of the Si ₃ N ₄ film is performed.

  Next, this cleaning method will be described.

  First, the quartz boat 14 not holding the semiconductor wafer 16 is inserted into the quartz inner tube 12 maintained at a temperature of 600 ° C.

  Next, vacuum exhaust is performed from the exhaust port 17 using a vacuum pump (not shown).

Next, NF ₃ gas is injected from the injection port 19 of the quartz nozzle 18 at a flow rate of 500 sccm, and the inside of the quartz reaction tube 11 is set to 10 Torr or more while evacuating from the exhaust port 17 using a vacuum pump (not shown). In this state, the quartz reaction tube 11 is cleaned.

Next, the supply of NF ₃ gas is stopped, and vacuum exhaust is performed from the exhaust port 17 using a vacuum pump (not shown) to exhaust the residual NF ₃ gas.

Next, N ₂ is caused to flow into the quartz reaction tube 11 from the quartz nozzle 18 and N ₂ purge is performed to remove NF ₃ in the quartz reaction tube 11.

Thereafter, vacuum exhaust is performed from the exhaust port 17 using a vacuum pump (not shown). Several cycles of evacuation and N ₂ purge are performed.

  Thereafter, the inside of the quartz reaction tube 11 is returned from the vacuum state to the atmospheric pressure state, and then the quartz boat 14 is lowered and pulled out from the quartz reaction tube 11.

When NF _{3 is} clean, quartz is etched at the same time as the Si ₃ N ₄ film is etched. Therefore, it is important that the Si ₃ N ₄ film is etched much and the quartz (SiO ₂ ) is not etched as much as possible.

FIG. 6 shows the relationship between pressure and etching selectivity. In this figure, the horizontal axis indicates the pressure in the quartz reaction tube 11, and the vertical axis indicates the ratio between the etching rate of the Si ₃ N ₄ film (ER (SiN)) and the etching rate of the quartz (ER (SiO ₂ )). ing. Referring to FIG. 6, it can be seen that the higher the pressure, the better the selectivity and the less likely it is to etch quartz (SiO ₂ ). For these reasons, the pressure is preferably 10 Torr or more. Further, by further increasing the pressure, the selectivity is further improved, and in addition, the etching rate is increased, so that the etching time can be shortened. For example, when the pressure is 10 Torr, the etching takes about 30 minutes. When the pressure is 70 Torr, the same etching can be performed in about 15 minutes.

The NF ₃ cleaning, by implementing _{the Si} 3 _{N 4} film every time 3000Å deposition, it is possible to form a _Si 3 _{N 4} film of particles free continuous 100Run without maintenance. FIG. 7 shows the data. In FIG. 7, the horizontal axis indicates the number of film formations, and is blank for every third time. A blank part indicates NF ₃ clean, and a vertical axis indicates the number of foreign matters on a wafer having a grain size of 0.18 μm or more. The cleaning using NF ₃ gas while evacuating by a vacuum pump injecting NF ₃ gas at a flow rate of 500ccm quartz reaction tube 11, keeping the quartz reaction tube 11 to 10 Torr (1300 Pa), the temperature The temperature was set at about 600 ° C. for 30 minutes. In FIG. 7, “top” refers to the 115th sheet from the bottom when 125 wafers are processed, “cnt” refers to the 66th sheet from the bottom, and “bot” refers to the 16th sheet from the bottom.

In addition, the time required for one NF ₃ clean is 2.5 hours (30 minutes for NF ₃ gas to flow, and the remaining time for boat up, evacuation, etc.), and 16 hours required for conventional maintenance. There are also advantages compared to.

When the Si ₃ N ₄ film is manufactured using BTBAS and NH ₃ , the maintenance frequency can be reduced as much as possible, and the generation of particles can be suppressed or prevented.

It is a schematic sectional drawing for demonstrating the vertical LPCVD film-forming apparatus used by one embodiment of this invention. It is the schematic for demonstrating the BTBAS supply apparatus used suitably in the film-forming apparatus used by one embodiment of this invention. It is the schematic for demonstrating the BTBAS supply apparatus used suitably in the film-forming apparatus used by one embodiment of this invention. BTBAS and NH ₃ is a diagram showing a film absorption rate of _{the Si} 3 _{N 4} film was formed as the material gas. BTBAS and NH ₃ is a diagram showing a film stress of _{the Si} 3 _{N 4} film was formed as the material gas. BTBAS and NH ₃ is a diagram for explaining a selective etching due to _{the Si} 3 _{N 4} film of NF ₃ was formed as a source gas. The NF ₃ cleaning, BTBAS and NH ₃ by performing the _Si 3 _{N 4} film formed as a raw material gas for each to 3000Å film formation, is a diagram for explaining a situation of continuous film formation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vertical-type film-forming apparatus 4, 5 ... BTBAS supply apparatus 11 ... Quartz reaction tube 12 ... Quartz inner tube 13 ... Heater 14 ... Quartz boat 15 ... Cap 16 ... Semiconductor wafer 17 ... Exhaust port 18, 21 ... Quartz nozzle 41 ... Constant temperature bath 51 ... BTBAS raw material tank 42, 52 ... BTBAS liquid raw material 53 ... Carrier gas inlet 35, 54, 55 ... Piping 43 ... Mass flow controller 44, 58 ... BTBAS supply port 56 ... Liquid flow control device 57 ... Vaporizer 45, 59 ... Pipe heating member

Claims (8)

The temperature of the reaction vessel made of quartz while maintaining the 600 ° C. or less, inserting the Bicester-tert-butyl amino silane and NH ₃ flowing into the reaction vessel as a source gas, a silicon nitride film into the reaction vessel Forming on the film-formed body,
By flowing NF ₃ gas as a cleaning gas into the reaction vessel, and a step of removing the silicon nitride which is formed in the reaction vessel,
In the step of removing the silicon nitride, the silicon nitride formed in the reaction vessel is peeled off due to film stress, or before the film thickness becomes such that microcracks are generated in the quartz due to film shrinkage. A process for producing a semiconductor device, wherein the process is carried out with the pressure in the reaction vessel maintained at 10 Torr or higher and the temperature at 600 ° C. With the temperature inside the reaction vessel made of quartz maintained at 600 ° C., bismutual butylamino silane and NH ₃ And flowing into the reaction vessel as a source gas to form a silicon nitride film on the deposition target inserted in the reaction vessel;
NF as a cleaning gas in the reaction vessel ₃ Flowing a gas to remove silicon nitride formed in the reaction vessel,
In the step of removing the silicon nitride, the silicon nitride formed in the reaction vessel is peeled off due to film stress, or before the film thickness becomes such that microcracks are generated in the quartz due to film shrinkage. A method for producing a semiconductor device, which is performed in a state where a pressure in a reaction vessel is maintained at 10 to 70 Torr and a temperature is maintained at 600 ° C. Inserting a boat holding the film formation body into a reaction vessel made of quartz ;
In the state where the temperature in the reaction vessel is kept at 600 ° C. or less, the butylaminosilane and NH ₃ are flowed as raw material gases into the reaction vessel, and the deposition material held by the boat in the reaction vessel. Forming a silicon nitride film on the film body;
A step of pulling out the boat holding the film formation target after the formation of the silicon nitride film from the reaction vessel;
Inserting the boat that does not hold the deposition target in the reaction vessel;
Flowing NF ₃ gas as a cleaning gas into the reaction vessel in which the boat not holding the film formation body is inserted to remove silicon nitride formed in the reaction vessel and the boat;
Withdrawing the boat that does not hold the film formation body from the reaction vessel, and
In the step of removing the silicon nitride, the silicon nitride formed in the reaction vessel is peeled off due to film stress, or before the film thickness becomes such that microcracks are generated in the quartz due to film shrinkage. A process for producing a semiconductor device, wherein the process is carried out with the pressure in the reaction vessel maintained at 10 Torr or higher and the temperature at 600 ° C. Inserting a boat holding the film formation body into a reaction vessel made of quartz;
While keeping the temperature of the reaction vessel 600 ° C., said to the reaction vessel and Bicester-tert-butyl amino silane and NH ₃ to flow in the raw material gas, the object held by the boat in the reaction vessel Forming a silicon nitride film on the film-forming body;
A step of pulling out the boat holding the film formation target after the formation of the silicon nitride film from the reaction vessel;
Inserting the boat that does not hold the deposition target in the reaction vessel;
Flowing NF ₃ gas as a cleaning gas into the reaction vessel in which the boat not holding the film formation body is inserted to remove silicon nitride formed in the reaction vessel and the boat ;
Withdrawing the boat that does not hold the film formation body from the reaction vessel, and
Removing the silicon nitride, silicon nitride is formed in the reaction vessel, or peeled off by the film stress, or, prior to a thickness of microcracks generated in the quartz by film contraction, the A method for producing a semiconductor device, which is performed in a state where a pressure in a reaction vessel is maintained at 10 to 70 Torr and a temperature is maintained at 600 ° C. The film stress of the silicon nitride is about twice the film stress of silicon nitride formed at 700 to 800 ° C. using SiH ₂ Cl ₂ and NH ₃ as source gases . The manufacturing method of the semiconductor device in any one . In the step of removing the silicon nitride, NF is put in the reaction vessel. ₃ The method for manufacturing a semiconductor device according to claim 1, wherein the gas is supplied at a flow rate of 500 sccm. Inserting a boat made of quartz holding a film formation body into a reaction vessel made of quartz;
In a state where the temperature in the reaction vessel is kept at 600 ° C. or less, the reaction vessel is filled with Vista-butylaminosilane and NH. ₃ And forming a silicon nitride film on the film formation body held by the boat in the reaction vessel,
A step of pulling out the boat holding the film formation target after the formation of the silicon nitride film from the reaction vessel;
Inserting the boat that does not hold the deposition target in the reaction vessel;
NF as a cleaning gas in the reaction vessel in which the boat not holding the film formation body is inserted ₃ Flowing gas to remove silicon nitride formed in the reaction vessel and the boat;
Withdrawing the boat that does not hold the film formation body from the reaction vessel, and
The step of removing the silicon nitride is performed before the silicon nitride formed in the reaction vessel or the boat is peeled off due to film stress or becomes a film thickness that causes microcracking in the quartz due to film shrinkage. In addition, the method is performed in a state where the pressure in the reaction vessel is maintained at 10 Torr or higher and the temperature is maintained at 600 ° C. Inserting a boat made of quartz holding a film formation body into a reaction vessel made of quartz;
In the state where the temperature in the reaction vessel is kept at 600 ° C., the film deposition film held by the boat in the reaction vessel by flowing the binary butyl aminosilane and NH ₃ as source gases in the reaction vessel. Forming a silicon nitride film on the body;
A step of pulling out the boat holding the film formation target after the formation of the silicon nitride film from the reaction vessel;
Inserting the boat that does not hold the deposition target in the reaction vessel;
Flowing NF ₃ gas as a cleaning gas into the reaction vessel in which the boat not holding the film formation body is inserted to remove silicon nitride formed in the reaction vessel and the boat;
Withdrawing the boat that does not hold the film formation body from the reaction vessel, and
The step of removing the silicon nitride is performed before the silicon nitride formed in the reaction vessel or the boat is peeled off due to film stress or becomes a film thickness that causes microcracking in the quartz due to film shrinkage. In addition, the method is performed in a state where the pressure in the reaction vessel is kept at 10 to 70 Torr and the temperature is kept at 600 ° C.

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