JP3070567B2 - Vertical reduced pressure vapor phase growth apparatus and vapor phase growth method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemical vapor deposition (CVD) process for manufacturing semiconductor products and electronic parts.
The present invention relates to a vertical reduced-pressure vapor-phase growth apparatus used for depositing a thin film on an object to be processed such as a silicon wafer by a method, and a vapor-phase growth method using the same.

[0002]

2. Description of the Related Art Conventionally, in manufacturing semiconductor products and electronic components, a chemical vapor deposition (CVD) method is used to deposit a thin film on an object to be processed such as a silicon wafer. As a reduced-pressure vapor deposition apparatus for performing this CVD method, a horizontal type, a vertical type, or the like is generally used. FIG. 3 shows a horizontal heat treatment furnace disclosed in Japanese Utility Model Laid-Open No. 50727/1993 as an example of a horizontal reduced pressure vapor phase growth apparatus. According to this, an object to be processed 77 such as a silicon wafer placed on a quartz board 76 is inserted into a furnace tube 73 by a cantilever 75, and the furnace port of the furnace tube 73 is closed by a quartz cap 74 and a door (not shown). In this state, a thin film is formed on the surface of the target object 77 by the CVD method. Note that this horizontal heat treatment furnace has a heater 7 around a furnace tube 73.
1, the cap 74 is provided with an exhaust port 74b for exhausting the gas in the furnace tube 73 and a space 74a maintained in a vacuum. The space 74a held in the vacuum improves heat insulation and heat retention at the furnace port, and prevents diffusion of heat exhaust, that is, heat radiation at the furnace port.

[0003] However, since the horizontal type reduced pressure vapor phase growth apparatus has problems in quality such as the uniformity of the resistivity and thickness of the growth layer and the crystal defects, the vertical type reduced pressure vapor deposition apparatus is generally used at present. It is used for

FIG. 4 shows a basic configuration of a conventional vertical reduced-pressure vapor deposition apparatus. The vertical type vacuum deposition apparatus has a quartz or SiC inner tube 32 and an outer tube 33 mounted vertically above a manifold 40 made of an alloy such as stainless steel disposed on a capping flange 34. The inside of the inner tube 32 (the inside of the double tube) becomes the reaction chamber 31. A heater 43 is provided around the outer pipe 33. Manifold 40
The joint between the outer tube 33 and the outer tube 33 is sealed by an O-ring 41 made of resin, and has a structure for maintaining airtightness. In addition, a cooling water circulation unit 42 for protecting the O-ring 41 from the thermal influence of the heater 43 is provided near the seal unit 40 inside the manifold 40. Cooling water is supplied to the cooling water circulating section 42 from cooling water supply means (not shown) and is circulated. The manifold 40 is equipped with an injector 39 (generally a nozzle made of quartz) for introducing a process gas for vapor-phase growth into the reaction chamber, and a vacuum pump (mechanical) (not shown) for the inside of the reaction chamber 31. An exhaust port 38 for reducing pressure and vacuum by a booster pump, a dry pump or the like is provided. An object 37 such as a silicon wafer is mounted and movable on a quartz or SiC boat 36 installed on the capping flange 34.

[0005] A vapor phase growth method for forming a thin film on an object to be processed using this vertical reduced pressure vapor phase growth apparatus will be described. The heater 43 heats the inside of the reaction chamber 31 to a high temperature (500 to 80).
(About 0 ° C.). In this state, the reaction chamber 31
After the inside is evacuated to a reduced pressure by a vacuum pump and a process gas is supplied from the injector 39 into the reaction chamber, a thin film is deposited on the surface of the processing target 37 by vapor phase growth. For example, NH ₃ and SiH ₂ C are used as process gases.
When l ₂ is introduced into the reaction chamber 31,
A Si ₃ N ₄ film is formed thereon.

As another example of such a vertical type reduced pressure vapor phase growth apparatus, a configuration described in Japanese Patent Application Laid-Open No. 4-165614 is shown in FIG. This configuration will be described. The screw member 5 provided in the processing object transfer chamber 52 will be described.
A boat 57 is fixed to an arm member 59 screwed into the boat 8, and an object 61 such as a silicon wafer is placed on the boat 57. The arm member 59 and the boat 57 move up and down by the rotation of the screw member 58, and the object 61 in the boat 57 is moved.
Can be inserted into and removed from the reaction chamber 51 (illustrated for simplicity). The load chamber 5 is adjacent to the processing object transfer chamber 52.
3 and an unloading chamber 54 are provided. Reaction chamber 5
A heater 60 is provided around 1 and a furnace port flange 55 is provided below the reaction chamber 51 (furnace port).
A heat insulating material 56 is provided on a portion of the inner surface of the furnace port flange 55 that comes into contact with the reaction gas. Workpiece 61
Is transferred from the load chamber 53 to the object transfer chamber 52,
After ascending and forming a thin film in the reaction chamber 51, it is processed and transported from the object transfer chamber 52 to the unload chamber 54.

[0007]

As described above, when NH ₃ and SiH ₂ Cl ₂ are introduced into the reaction chamber as the process gas, the reaction of the process gas involves the addition of NH ₄ Cl other than the deposition of the Si ₃ N ₄ film. Is generated. This NH ₄ Cl evaporates at a relatively low temperature (about 130 ° C.). In the high temperature (about 500 to 800 ° C.) reaction chamber 31 shown in FIG.
Although only the i ₃ N ₄ film is deposited on the processing target 37, NH ₄ Cl is discharged from the inner wall surface 40 a of the manifold 40 having a low temperature and the exhaust port 38 of the manifold 40 to the inside of the exhaust pipe / vacuum pump. Is generated.

The generation of NH ₄ Cl will be described.
The process gas passes between the inner pipe 32 and the outer pipe 33 from the inside of the inner pipe 32 and passes through the manifold 40.
Is discharged from an exhaust pipe (not shown) through the exhaust port 38. By the way, the resin O-ring 41 for sealing the joint between the manifold 40 and the outer pipe 33 generally only has heat resistance of about 200 ° C. at the maximum. Therefore, in order to protect the O-ring 41 from the thermal influence of the reaction chamber heater 43, a cooling water circulating section 42 inside the manifold 40 is provided.
The cooling water is circulated to keep the seal portion 40b at a low temperature. Therefore, when the reacted gas (about 500 to 800 ° C.) passes through the inside of the manifold 40 cooled by the circulating cooling water, the temperature of the unreacted gas at the time of forming the Si ₃ N ₄ film is lowered. , NH ₄ Cl are produced.
This product naturally adheres to the manifold inner wall surface 40a (contact surface with the reaction gas) and the exhaust pipe inner wall surface (not shown). The adhered product is peeled off from the inner wall surface 40a of the manifold and rolled up in the reaction chamber 31 as the series of vapor phase growth processes is repeated, and adheres as particles on the object to be processed 37. As a result, the quality of the semiconductor product is reduced. Deterioration and yield loss will be caused. In order to prevent the generation of particles and to operate the device stably,
Frequent maintenance (removal and cleaning of products adhering to the inner wall surface 40a of the manifold) needs to be performed, and the operation rate of the apparatus decreases.

The configuration disclosed in Japanese Patent Application Laid-Open No. HEI 4-165614, as shown in FIG. 5, employs a vertical type reduced pressure vapor phase growth apparatus in which a furnace opening flange 55 of a reaction chamber 51 covered with a heater 71 and heated. A heat insulating material 56 is provided on the inner surface. Therefore, even if the furnace port flange 55 is cooled by the cooling means, the portion of the furnace port flange 55 that is in contact with the reaction gas is kept warm, the reaction gas is not lowered in temperature, and generation and adhesion of products are suppressed, and Particles are less likely to adhere to the surface 61. However, the furnace port flange 55 and the manifold are generally formed of an alloy such as stainless steel, and it is technically difficult to make close contact bonding when attaching the heat insulating material 56 made of quartz or ceramics, and the manufacturing cost increases. Poor feasibility. In particular, when the heat insulating material 56 is attached to the furnace port flange 55 or the inner surface of the manifold, the reaction gas enters when a slight gap is formed between the inner surface of the furnace port flange 55 or the manifold and the outer peripheral surface of the heat insulating material 56, and the reaction product The substance (NH ₄ Cl) adheres, and eventually causes particles to be generated on the object to be processed. Moreover, in this case, if the product is firmly fixed between the core flange 55 or the manifold and the heat insulating material 56, even if the cleaning of the inner wall surface of the core flange 55 or the manifold and the removal of the product are performed, the heat insulating material 56 is not removed. It cannot be easily removed.

[0010] The configuration disclosed in Japanese Utility Model Laid-Open No. 5-50727 can also secure the heat retention at the furnace port. However, this relates to a horizontal type reduced pressure vapor phase growth apparatus as shown in FIG. 3, and as described above, a vertical type reduced pressure vapor phase growth apparatus in which a product is attached to the gas for vapor phase growth by lowering the temperature of the manifold. It does not solve the problems specific to. In addition, the configuration in which the space 74a held in a vacuum is provided in the quartz cap 74 is difficult to manufacture and expensive, and has a problem in durability of the material, which is poor in feasibility. Further, as described above, such a horizontal reduced-pressure vapor deposition apparatus has problems in quality such as uniformity of resistivity and thickness of a growth layer and crystal defects.

Therefore, an object of the present invention is to provide a vertical decompression vapor phase epitaxy apparatus having no problems such as uniformity of resistivity and thickness of a growth layer and crystal defects, while keeping the seal portion of a manifold at a low temperature, and An object of the present invention is to reduce the temperature of the inner wall surface of the manifold (the contact surface with the reaction gas) in the reaction chamber, suppress the adhesion of the reaction product to the wall surface, and prevent the generation of particles on the object to be processed. A further object of the present invention is to make such a configuration simple and inexpensive, and also to improve the quality of semiconductor products and the stable operation and operation rate of a vapor phase growth apparatus.

[0012]

SUMMARY OF THE INVENTION The present invention provides a vertical decompression system having a reaction chamber in which a process gas is introduced and a thin film is formed on the surface of an object to be processed, and a manifold for sealing the reaction chamber. In the vapor phase growth apparatus, the manifold includes an exhaust port configured to exhaust a reaction gas from the reaction chamber, a cooling water circulation unit configured to supply and circulate cooling water,
It is characterized by having a hollow portion that separates the inside of the manifold into a high-temperature portion and a low-temperature portion by a heat insulating action generated by vacuuming.

[0013] The high-temperature portion of the manifold includes an inner wall surface in contact with the reaction gas, and the low-temperature portion includes a seal portion for sealing the reaction chamber.

The low temperature section includes the cooling water circulation section.

An O-ring made of resin is attached to the seal portion.

A vacuum pump connected to the exhaust port for sucking the reaction gas is provided, and the vacuum pump is also connected to the hollow exhaust port of the hollow section.

There is provided a heater for heating the reaction chamber.

In the vapor phase growth method according to the present invention, the vertical type reduced pressure vapor phase growth apparatus having any one of the above structures is used, and the vacuum pump is used to evacuate the hollow portion to have an adiabatic function. And the high-temperature portion, the process gas is introduced while the pressure in the reaction chamber is reduced by the vacuum pump to form a thin film on the object.

According to such a configuration, by evacuating the hollow portion provided in the manifold, a heat insulating action is generated in the vacuum space layer, and a low temperature state is desired to be ensured by circulation of the cooling water. And the inner wall surface side (reactant gas contact surface side) of the manifold where it is desired to maintain a high temperature state in the reaction chamber, it is possible to ensure a contradictory temperature state. As a result, the sealing property of the reaction chamber can be maintained without deterioration of the resin O-ring, and the reaction gas passes through and is discharged from the inner wall surface of the manifold at a high temperature. The deposition and adhesion of the product on the surface) are suppressed, and the generation of particles due to the peeling of the product can be prevented.

If a vacuum pump conventionally used for exhausting the reaction gas in the reaction chamber is used to achieve the vacuum in the hollow portion, there is no need to newly construct a vacuum exhaust system, and it is possible to achieve a reasonable ratio. It is.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to FIG. FIG. 1 is a cross-sectional view showing the configuration of a vertical reduced pressure vapor deposition apparatus according to the present invention,
This shows a state where the object 7 is set.

The vertical reduced pressure vapor phase epitaxy apparatus of the present invention comprises an inner tube 2 made of quartz or SiC above a manifold 10 made of an alloy such as stainless steel on a capping flange 4.
And the outer tube 3 are mounted vertically vertically so as to overlap with each other, and the inner tube 2 (inside of the double tube)
Becomes the reaction chamber 1. Heater 1 around outer tube 3
3 are provided.

An injector 9 for introducing a process gas for vapor phase growth into the reaction chamber 1 is mounted on the manifold 10 and a vacuum pump 1
At 7, an exhaust port 8 for reducing pressure and vacuum is provided. An object to be processed 7 such as a silicon wafer is made of quartz or Si on a heat insulating cylinder 5 installed on the capping flange 4.
It is loaded so as to be transferable on a boat 6 made of C.

The joint between the manifold 10 and the outer tube 3 is sealed by an O-ring 11 made of resin. Since the heater 13 radiates heat so as to heat the reaction chamber 1 to a high temperature (about 500 to 800 ° C.), the inside of the manifold 10 is protected to protect the resin O-ring 11 having a heat resistant temperature of about 200 ° C. from the thermal influence of the heater 13. The cooling water circulation unit 12 is provided near the seal unit 10e. Cooling water is supplied from the cooling water supply unit 14 to the cooling water circulation unit 12.

The inner wall surface 10a (reactant gas exhaust contact surface) of the manifold rises upward along the inner wall surface of the outer tube 3 to a height near the lowermost portion of the heater 13 on the outer periphery of the outer tube 3. Is formed.
Portion 1 rising to the vicinity of the bottom of this heater 13
0d to the vicinity of the reaction gas exhaust port 8
0b is provided. Here, the rising portion 10d of the inner wall surface 10a of the manifold is formed so as to be a wall that blocks the flow of gas from the inside of the reaction chamber 1 to the exhaust port 8 toward the seal portion 10e. A hollow portion 10b is provided inside the rising portion 10d. A hollow part exhaust port 10c communicating with the hollow part 10b is provided on the end face of the manifold 10. The hollow portion 10b is
It can be easily manufactured by welding the same type of alloy,
At the time of manufacturing, there is no need to evacuate the inside of the hollow portion, so that it can be easily manufactured at low cost.

Next, the evacuation system shown on the left side of FIG. 1 will be described. A vacuum pump 17 is connected to an exhaust port 8 via an exhaust pipe 18 and a main valve 20 to evacuate the reaction chamber 1 for heat treatment (vapor phase growth) or to suck out exhaust gas after introducing process gas. . A vacuum sensor 19 for checking a vacuum state is attached to the exhaust pipe 18.

The exhaust port 1 in the hollow portion of the manifold 10
0c is connected to the exhaust pipe 18 through the hollow exhaust pipe 21.
Is connected between the main valve 20 and the vacuum pump 17. Therefore, the hollow portion 10b can be evacuated by the vacuum pump 17. A valve 2 is provided in the hollow exhaust pipe 21.
2 are provided so that the timing of evacuation of the hollow portion 10b can be controlled. When the valve 22 is opened and the vacuum pump 17 is operated, the hollow portion 10b in the manifold 10 becomes a vacuum space layer, and a heat insulating action occurs. Due to this heat insulating action, a low temperature state is ensured by the circulation of the cooling water on the seal portion 10e side of the manifold 10 across the hollow portion 10b, and the inner wall surface 10a side (reaction gas contact surface side) of the manifold 10 is heated by the heater 13 , A high temperature state in the reaction chamber 1 is secured. By using the vacuum pump 17 conventionally provided for exhausting the reaction chamber 1 of the vapor phase growth apparatus, it is possible to easily maintain a vacuum state without increasing the number of new components.

Next, a flow of a series of operations for depositing a thin film on a workpiece 7 such as a silicon wafer by the vapor phase growth method of the present invention will be described with reference to FIGS.

First, an object 7 such as a silicon wafer is placed on the boat 6 and inserted into the reaction chamber 1 (in the inner tube 2) (step A). Then, before starting the vapor phase growth process, the valve 22 is opened, and the hollow portion 10b of the manifold 10 is opened.
Is evacuated by the vacuum pump 17, the valve 22 is closed, and the hollow portion 10b of the manifold 10 is maintained in a vacuum state (step B). In the cooling water circulating section 12 of the manifold 10, the cooling water supplied from the cooling water supply means 14 is circulated, and the heater 13 around the outer pipe 3 is in a heated state (step C). Next, while the main valve 20 of the reaction chamber exhaust pipe 18 is opened and the pressure inside the reaction chamber 1 is reduced by the vacuum pump 17, the process gas (NH ₃ and SiH ₂ C in the present embodiment) is introduced into the reaction chamber 1.
l ₂ ) is supplied, and a thin film of Si ₃ N ₄ is vapor-phase grown on the object 7 (step D).

Conventionally, an N ₃ film is grown and deposited at the same time as an N ₃ film.
H ₄ Cl was generated and adhered to the inner wall surface of the manifold. However, in the case of this embodiment, the hollow portion 1 in a vacuum state
Ob, the manifold 10 is separated into a low-temperature portion (the seal portion 11e side) and a high-temperature portion (the inner wall surface 10a side), so that the temperature of the inner wall surface 10a of the manifold 10 is set to the evaporation temperature of NH ₄ Cl. (About 130 ° C.) or more, and NH ₄ Cl does not adhere to the inner wall surface 10 a of the manifold 10. Even if this series of vapor deposition processes is repeated, no particles are generated.

The hollow portion 10b of the manifold 10
In the initial stage after the replacement of the hollow exhaust pipe 21, a vacuum is evacuated in advance, and the valve 22 is always closed and the vacuum pump is operated during the vapor phase growth process, even if the vacuum state is maintained. Alternatively, the evacuation may be continued and is not particularly limited.

[0032]

As described above, according to the vertical type reduced pressure vapor phase growth apparatus and the vapor phase growth method using the same according to the present invention, the vacuum heat insulating layer is provided by providing the hollow portion capable of being evacuated in the manifold. Can be formed, while maintaining the manifold seal portion at a low temperature and maintaining the manifold inner wall surface (the contact surface with the reaction gas) at a high temperature close to the reaction chamber,
It is possible to prevent the temperature of the reaction gas from lowering, thereby suppressing the reaction products from adhering to the inner wall surface of the manifold and the like, and thereby preventing the generation of particles on the object to be processed.

The heat insulating effect for separating the manifold into a high-temperature part and a low-tone part can be obtained by evacuating the hollow part using a vacuum pump provided in a conventional vertical vacuum deposition apparatus. Therefore, the structure can be easily manufactured with a simple structure, and a low-cost and more feasible configuration can be obtained. And the quality improvement of a semiconductor product and the stable operation | movement of a vapor phase growth apparatus and an improvement of an operation rate can be achieved.

Furthermore, the vertical reduced pressure vapor phase epitaxy apparatus of the present invention is excellent in uniformity of the resistivity and thickness of a grown layer, has few crystal defects, and can form a high quality thin film.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration of an embodiment of a vertical reduced pressure vapor deposition apparatus of the present invention.

FIG. 2 is a flowchart showing a vapor phase growth method using the vertical reduced pressure vapor phase growth apparatus shown in FIG.

FIG. 3 is a cross-sectional view illustrating an example of a configuration of a conventional horizontal reduced pressure vapor deposition apparatus.

FIG. 4 is a cross-sectional view showing an example of a configuration of a conventional vertical reduced pressure vapor deposition apparatus.

FIG. 5 is a cross-sectional view showing another example of the configuration of a conventional vertical reduced pressure vapor deposition apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction chamber 2 Inner pipe 3 Outer pipe 4 Capping flange 5 Heat retention tube 6 Boat 7 Workpiece (silicon wafer) 8 Exhaust port 9 Injector 10 Manifold 10a Inner wall surface 10b Hollow section 10c Hollow section exhaust port 10d Rising section 10e Seal section DESCRIPTION OF SYMBOLS 11 O-ring 12 Cooling water circulating part 13 Heater 14 Cooling water supply means 17 Vacuum pump 18 Exhaust pipe 19 Vacuum sensor 20 Main valve 21 Hollow part exhaust pipe 22 Valve 31 Reaction chamber 32 Inner pipe 33 Outer pipe 34 Capping flange 35 Heat insulation cylinder 36 Boat 37 Object to be processed (silicon wafer) 38 Exhaust port 39 Injector 40 Manifold 40a Inner wall surface 40b Seal part 41 O-ring 42 Cooling water circulation part 43 Heater 51 Reaction chamber 52 Object transfer chamber 53 B Loading chamber 54 Unloading chamber 55 Furnace opening flange 56 Heat insulator 57 Boat 58 Screw member 59 Arm member 60 Heater 61 Workpiece (silicon wafer) 71 Heater 73 Furnace tube 74 Cap 74a Space 74b Exhaust port 75 Cantilever 76 Quartz board 77 Object to be processed (silicon wafer)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/31 H01L 21/205 C23C 16/00 C30B 23/00

Claims (7)

(57) [Claims] 1. A vertical reduced-pressure vapor deposition apparatus comprising: a reaction chamber into which a process gas is introduced to form a thin film on a surface of an object to be processed; and a manifold to which the reaction chamber can be hermetically attached. However, an exhaust port for exhausting the reaction gas from the reaction chamber, a cooling water circulating section through which cooling water is supplied and circulated, and a heat insulating action caused by evacuation to convert the inside of the manifold into a high temperature section and a low temperature section A vertical reduced-pressure vapor deposition apparatus having a hollow portion to be separated. 2. The vertical depressurization according to claim 1, wherein the high-temperature portion of the manifold includes an inner wall surface in contact with the reaction gas, and the low-temperature portion includes a sealing portion for sealing the reaction chamber. Vapor growth equipment. 3. The vertical reduced-pressure vapor deposition apparatus according to claim 1, wherein the low temperature section includes the cooling water circulation section. 4. The vertical type reduced pressure vapor deposition apparatus according to claim 2, wherein a resin O-ring is attached to the seal portion. 5. The vacuum pump according to claim 1, further comprising a vacuum pump connected to the exhaust port for sucking the reaction gas, wherein the vacuum pump is also connected to a hollow exhaust port of the hollow section. 2. The vertical reduced pressure vapor deposition apparatus according to claim 1. 6. The vertical reduced-pressure vapor deposition apparatus according to claim 1, further comprising a heater for heating the reaction chamber. 7. The vertical type reduced pressure vapor deposition apparatus according to claim 1, wherein the vacuum part is evacuated by the vacuum pump to have an adiabatic function, and the manifold is cooled to the low temperature part. And a high-temperature section in which the process gas is introduced while the pressure in the reaction chamber is reduced by the vacuum pump to form a thin film on the object.