JPH11186170A - Method and device for forming film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for forming film by which films can be formed without causing a discharge route to be blocked with by-products left after the films are formed. SOLUTION: A film forming device respectively forms films on objects mounted on a quartz board 14 by introducing a reaction gas to a reaction furnace 13 after the boat 14 is carried in the furnace 13. An electric heater 17 which vaporizes resulted by-products of reaction adhering to the boat 14 by heating the boat 14 on the outside of the furnace 13 after the films are formed is provided on the outside of the furnace 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming method and a film forming apparatus for a semiconductor device, and more particularly, to heating a supporting means for a film forming object outside a reaction vessel after a film forming process and attaching the supporting means to the supporting means. The present invention relates to a film forming method and a film forming apparatus in which a reaction by-product is vaporized and a discharge path is not blocked by a by-product remaining after film formation.

[0002]

2. Description of the Related Art Recently, an LP-SiN film has been frequently used as an insulating film when a semiconductor device is formed. The LP-SiN film is generally formed using a vertical reduced pressure CVD apparatus and using NH ₃ gas and SiH ₂ Cl ₂ gas as reaction gases. In this case, the reaction of film formation is 2
NH ₃ + SiH ₂ Cl ₂ → Si + 2NH ₄ Cl,
NH ₄ Cl (ammonium chloride), which is a reaction by-product, is generated. This ammonium chloride has a temperature of about 100 ° C.
Below, it becomes a white powder, causing particles or clogging of piping. Therefore, when forming an LP-SiN film in this low-pressure CVD apparatus, it is important to prevent ammonium chloride from entering the reaction furnace in order to reduce particles.

[0003] In a general LP-CVD apparatus, in a standby state (standby state) after a film forming process, a quartz boat in which a semiconductor wafer to be processed is stored is not inserted into the reaction furnace but outside the reaction furnace. Has been drawn to
In this CVD apparatus for forming LP-SiN, when the quartz boat is pulled out of the reaction furnace and is on standby,
Ammonium chloride remaining after the formation of the SiN film and remaining attached to a portion having a complicated shape, such as a quartz boat table below the quartz boat, is cooled outside the reaction furnace to form a powder. The powdered ammonium chloride is carried into the reaction furnace in the next processing step and becomes a particle generation source. Therefore, in a CVD apparatus for forming LP-SiN, the quartz boat is kept inserted in the reaction furnace during standby to prevent reaction by-products from adhering to the lower part of the quartz boat or the like.

[0004] As shown in FIG. 6, a conventional CVD apparatus 1 for forming LP-SiN comprises a reactor 2 comprising an outer tube 2a and an inner tube 2b, and an outer tube 2a.
And an exhaust pipe 5 provided on a flange 4 connecting the lower ends of the outer tube 2a and the inner tube 2b. A quartz boat 6 in which a plurality of wafers (not shown) to be subjected to film formation processing in the reaction furnace 2 are stacked and supported in a plurality of stages is mounted on a quartz boat table 7 via a heat retaining cylinder 7a. At the time of film processing, the lower end opening is inserted together with the heat retaining cylinder 7 a into the reaction furnace 2 closed by the quartz boat table 7. An exhaust vacuum pump 8 is connected to the exhaust pipe 5. When the quartz boat 6 is in a standby state with the quartz boat 6 inserted into the reaction furnace 2, the purge is performed in the reaction furnace 2 by the N ₂ flow under the atmospheric pressure.

[0005]

However, when the quartz boat 6 is inserted into the reaction furnace 2 and the purge is performed in the reaction furnace 2 by the N ₂ flow under the atmospheric pressure, the reaction by-products are generated. The discharge path communicating with the exhaust pipe 5 is clogged by the ammonium chloride. That is, as shown in FIG. 7, when purging with N ₂ gas, the valve of the exhaust path leading to the vacuum pump 8 is closed, the pressure in the reactor 2 becomes normal pressure, and the N ₂ gas fed into the reactor 2 is released. And the ammonium chloride gas vaporized during the standby time are both discharged as exhaust gas from the exhaust pipe 5 through the vent line 9 to the outside of the LP-CVD apparatus 1 by the purge pressure. On the way, clogging with ammonium chloride occurs in the vent line 9 composed of a thin exhaust pipe.

[0006] This is because ammonium chloride remaining as a reaction by-product after deposition of the LP-SiN film adheres to a portion having a complicated shape such as the quartz boat table 7 and the like, and is cooled to a powdery state during the evacuation. This is because Vent line 9
If clogging occurs, maintenance of the device is required to eliminate the clogging, and the downtime of the device increases, and the operation rate decreases.

On the other hand, Japanese Patent Application Laid-Open No. Hei 5 (1993) discloses a heat treatment apparatus for preventing reaction products from adhering to the lower part of a quartz boat during heat treatment.
No. 291158. This heat treatment apparatus includes: a tubular reaction vessel having an opening for inserting a support that horizontally supports a plurality of objects to be processed from below, wherein the processing of the object is performed by a reaction gas introduced; In a heat treatment apparatus including: a lid at the opening that keeps the inside of the tubular reaction vessel airtight; and a heating unit provided to surround the tubular reaction vessel, the inside of the tubular reaction vessel of the lid is provided. And a heating device for heating the reaction product to prevent the adhesion of the reaction product. " In this heat treatment apparatus, the lid is heated while the support (quartz boat) is carried into the reaction vessel by a heating device provided on the inner surface of the reaction vessel, and the reaction products are placed below the reaction vessel and on the lid. Because it does not adhere,
It does not generate a contamination source of the semiconductor wafer to be processed.

However, the heat treatment apparatus described in this publication heats the lower part of the quartz boat mounted in the reaction vessel to prevent the reaction products from adhering to the lower part of the boat. The gas is discharged to the outside through the piping of the reaction vessel. Therefore, it does not suggest the above-mentioned technical problem of cooling during the evacuation, solidifying into a powdery state, and clogging the piping, and does not disclose a solution thereto.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned prior art, and has as its object to provide a film forming method and a film forming apparatus in which a discharge path is not blocked by a by-product remaining after film forming. And

[0010]

In order to achieve the above object, according to the present invention, a film formation target is mounted on a support means,
In the film forming method of introducing a reaction gas into the reaction vessel into which the supporting unit is carried, and performing a film forming process on the film forming target,
A film forming method is provided, wherein the supporting means is heated outside the reaction vessel after the film forming process, and a reaction by-product adhered to the supporting means is vaporized.

According to the above construction, after the film formation is completed, the supporting means on which the object to be formed is mounted is pulled out of the reaction vessel, and the lower end of the supporting means is heated outside the reaction vessel, and the reaction by-product adhering to the supporting means is attached. Evaporation of the material takes place outside the reaction vessel. Accordingly, the discharge route of the reaction container is not blocked by the reaction by-product remaining after the film formation.

Further, in order to realize the above-mentioned film forming method, in the present invention, a film forming object is mounted on a supporting means, and a reaction gas is introduced into a reaction vessel into which the supporting means is carried. In a film forming apparatus for performing a film forming process, the supporting means is installed outside the reaction vessel after the film forming processing, and the supporting means is heated outside the reaction vessel to vaporize a reaction by-product adhered to the supporting means. A film forming apparatus provided with a heating means is provided.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic explanatory view of a low-pressure CVD apparatus for forming LP-SiN according to an embodiment of the present invention. FIG. 2 is an explanatory view showing a quartz boat and an electric heater inserted into the reaction furnace of FIG. FIG. 3 is an explanatory diagram of a vaporized state of a reaction by-product due to heating by the electric heater of FIG.

As shown in FIG. 1, a vertical LP-CVD apparatus 10 has a reaction furnace (reaction vessel) 13 covered with a heater 12 at an upper part in an apparatus case 11.
A quartz boat (supporting means) 14 is disposed below. The quartz boat 14 is formed so that a plurality of semiconductor wafers (not shown) to be subjected to a film forming process can be mounted horizontally, and a quartz boat table 16
Are integrally mounted. The quartz boat table 16 can be freely moved up and down and rotated by a lifting mechanism and a rotating mechanism (not shown). It is withdrawn from the furnace 13. Quartz boat 14
The quartz boat table 16 is made of, for example, quartz glass or Si.
C or the like.

A reaction furnace 13 is provided at the bottom of the apparatus case 11.
An annular electric heater (heating means) 17 is provided outside the reaction furnace 13 so as to surround the quartz boat table 16 at the lower end of the quartz boat 14 which is drawn out of the heater 12 and located below the heater 12. On the side of the electric heater 17, a wafer transfer machine 18 for mounting a semiconductor wafer on the quartz boat 14 or taking out the semiconductor wafer from the quartz boat 14 is provided. An operation panel 19 is provided on a lower outer surface of the device case 11.

As shown in FIG. 2, a reaction furnace 13 surrounded by a heater 12 includes an outer tube 20 and an inner tube 2.
1 is connected to the flange 22 at the lower end, and is formed in a double-layered cylindrical shape with an open lower end. An exhaust pipe 23 is attached to the flange 22 so as to communicate with a reaction space in the reaction furnace 13 via a gap between the outer tube 20 and the inner tube 21. The exhaust pipe 23 branches off into a vent line 24 (see FIG. 3) on the way, and then is evacuated to a vacuum pump 2.
5 (see FIG. 3).

When the quartz boat 14 is raised, the quartz boat 14 is inserted into the reaction furnace 13 together with the heat retaining tube 15,
The upper surface of the quartz boat table 16 contacts the lower end of the flange 22 to close the lower end opening of the reaction furnace 13. When the quartz boat 14 descends, the quartz boat 14 moved below the reactor 13
The quartz boat table 16 at the lower end is surrounded by an electric heater 17, and the electric
Is heated.

As shown in FIG. 3, after the formation of the LP-SiN film is completed, the quartz boat 14 is pulled out of the reaction furnace 13 and the inside of the reaction furnace 13 is purged by the N ₂ flow under the atmospheric pressure. Quartz boat 14 is reactor 13
, The lower end opening of the reaction furnace 13 is closed by a lid (not shown) provided in the reaction furnace 13. The quartz boat table 16 in which the quartz boat 14 goes out of the reaction furnace 13 and is surrounded by the electric heater 17 is heated to 100 ° C. by the electric heater 17.
It waits in the state heated above.

When purging with N ₂ gas, the vacuum pump 2
The valve in the exhaust path leading to 5 is closed, and the pressure in the reaction furnace 13 becomes normal pressure. Therefore, during the descent of the quartz boat 14, but N ₂ gas is discharged to the outside the reactor 13 from the lower end of the reactor 13 at a purge pressure, the waiting quartz boat 14 which the lower end opening is closed, N ₂ gas Is similarly sent out from the exhaust pipe 23 to the vent line 24 at the purge pressure and the LP-CVD apparatus 10
It is discharged outside.

When the quartz boat table 16 is heated, ammonium chloride (NH ₄ Cl) which remains as a reaction by-product after the LP-SiN film is formed and adheres to a portion having a complicated shape such as the quartz boat table 16. Are vaporized and diffused as ammonium chloride gas. The vaporized and diffused ammonium chloride gas is supplied to the reaction vessel 1 by heating the quartz boat table 16.
3, the exhaust pipe 2 communicating with the reactor 13
3 does not flow, and is not cooled and becomes powdery during exhaustion through the exhaust pipe 23. Therefore, the vent line 24 composed of a thin exhaust pipe is not clogged with the powdery ammonium chloride.

FIG. 4 is an explanatory view similar to FIG. 2 in which a heating element is used instead of an electric heater, and FIG. 5 is an explanatory view of a vaporized state of a reaction by-product by heating the heating element in FIG. is there. In this example, a heating element that circulates a heating fluid is used as the heating means instead of the electric heater.

As shown in FIG. 4, the heating element 26 is formed in a concave shape in which the quartz boat table 16 can be placed in a buried state.
The bottom and side surfaces of the quartz boat table 16 can be heated by circulation of the heating fluid introduced from the introduction tube 27 and discharged from the discharge tube 28. As shown in FIG.
After the N film is formed, the quartz boat 14 descends and the quartz boat 14 exits the reaction furnace 13 and the quartz boat table 1
The quartz boat table 16 is heated to 100 ° C. or higher by the heater 26.

As described above, when the quartz boat table 16 is heated outside the reaction furnace 13, the quartz boat table 16 remains as a reaction by-product after the LP-SiN film is formed, and the quartz boat table 16 and the like have complicated shapes. When the ammonium chloride adhering to the gas is vaporized and diffused as ammonium chloride gas, the reaction furnace 1
3 does not flow into the exhaust pipe 23 communicating with the exhaust pipe 3. Other configurations, functions and effects are the same as those of the embodiment shown in FIGS.

As described above, the quartz boat table 16 is heated only outside the reaction furnace 13 by the electric heater 17 or the heating element 26, and remains as a reaction by-product after the LP-SiN film is formed, and the quartz boat table 16 and the like are not heated. Ammonium chloride adhered to is vaporized and diffused as an ammonium chloride gas outside the reaction furnace 13. Therefore, since ammonium chloride, which is a particle generation source, does not enter the reaction furnace 13, particles can be reduced and the quality of a semiconductor device can be improved. In addition, since the vent line 24, which is the discharge path of the reaction furnace 13, is not clogged by ammonium chloride, the CV for forming LP-SiN for eliminating the clogging is eliminated.
The maintenance frequency of the D device 10 is reduced, and the operation rate of the device is improved.

In the present invention, the same effect can be obtained not only in the above-described vertical type low pressure CVD apparatus but also in a horizontal type low pressure CVD apparatus. Further, the quartz boat table 16 is not limited to the electric heater 17 or the heating body 26 but may be formed by another heating method.
May be heated.

The present invention can be applied not only to the formation of the SiN film but also to a film formation process using other various reaction gases. Further, the present invention is not limited to the CVD apparatus, and is applicable to a heating furnace for annealing, diffusion processing, and the like.

[0027]

As described above, according to the film forming method of the present invention, after the film formation is completed, the supporting means on which the object to be formed is mounted is pulled out of the reaction vessel, and the supporting means is removed outside the reaction vessel. Since the lower end is heated and the reaction by-products adhering to the supporting means are vaporized outside the reaction vessel, the reaction by-products, which are the source of particles, do not enter the reaction vessel, and the particles can be reduced. Brings improved device quality. In addition, since the reaction by-product does not block the discharge path of the reaction vessel, the frequency of maintenance of the device for eliminating the clogging is reduced, and the operation rate of the device is improved.

Further, according to the film forming apparatus of the present invention, the effect can be obtained by performing the above film forming method.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a low pressure CVD apparatus for forming LP-SiN according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing a quartz boat and an electric heater inserted into the reaction furnace of FIG.

FIG. 3 is an explanatory view of a vaporized state of a reaction by-product by heating of the electric heater of FIG. 2;

FIG. 4 is an explanatory view similar to FIG. 2 but using a heating element instead of an electric heater.

FIG. 5 is an explanatory diagram of a vaporized state of a reaction by-product due to heating of the heating body in FIG. 4;

FIG. 6 is a schematic explanatory view of a conventional LP-CVD apparatus.

FIG. 7 is an explanatory view showing the flow of vaporized reaction by-products in the LP-CVD apparatus of FIG. 6;

[Explanation of symbols]

10: LP-CVD apparatus, 11: apparatus case, 12: heater, 13: reaction furnace, 14: quartz boat, 15: heat insulating cylinder, 16: quartz boat table, 17: electric heater, 18: wafer transfer machine, 19: Operation panel, 20: outer tube, 21: inner tube, 22: flange, 23: exhaust pipe, 24: vent line, 25: vacuum pump, 26:
Heating body, 27: introduction pipe, 28: discharge pipe.

Claims (4)

[Claims] 1. A film forming method in which a film formation target is mounted on a support means, a reaction gas is introduced into a reaction vessel into which the support means is carried, and a film formation process is performed on the film formation object. A film forming method, characterized in that the supporting means is heated outside the reaction vessel later, and a reaction by-product adhering to the supporting means is vaporized. 2. A film forming apparatus for mounting a film formation target on a support means, introducing a reaction gas into the reaction vessel into which the support means is carried, and performing a film formation process on the film formation object. And a heating means for heating the supporting means outside the reaction vessel after the film forming process to vaporize a reaction by-product adhered to the supporting means. 3. The film forming apparatus according to claim 2, wherein said heating means is an electric heater. 4. The film forming apparatus according to claim 2, wherein said heating means is a heating element for circulating a heating fluid.