JPH07335555A - Chemical vapor growth device and retention tool - Google Patents

Abstract

PURPOSE:To suppress adhesion of foreign objects to a wafer due to the turbulence of treatment gas by forming a gas flow adjustment body with a body part which faces an object to be treated and is in the same shape as the object to be treated and a conical part with a sharp tip which is formed being stretched to the boy part. CONSTITUTION:A treatment gas 10 advancing the lower part of a boat 4 passes through a slit 25 and advances between erected wafers 3, where a gas flow adjustment body 30 is laid out at the front row and the last row of the wafer rows of the boat 4. The gas flow adjustment body 30 is made of a material with superb heat resistance and chemical resistance such as quartz. The gas flow adjustment body 30 consists of a cylindrical body part 31 consisting of the same diameter as that of the wafers 3 and a conical part 32 consisting of the conical part being extended to the body part 31. The center shaft of the body part 31 which becomes a cylinder matches that of the conical part 32 which becomes a conical body part and the gas flow adjustment body 30 is placed at the boat 4 so that the body part 31 can lie.

Description

Detailed Description of the Invention

[0001]

The present invention relates to chemical vapor deposition (CV).
D: Chemical Vapor Deposition) device and holder, particularly low-pressure (pressure-reduced) CVD device. For example, semiconductor wafers are vertically arranged on a holder (for example, a holder called a boat) and one end of a wafer row ( A so-called hot wall type (Ho) that forms a CVD film on the wafer surface by flowing a processing gas from the front end side to the other end (rear end) side
t Wall Type) low-pressure CVD equipment and effective technology.

[0002]

2. Description of the Related Art In manufacturing a semiconductor device, a silicon oxide film (SiO2 film), a polysilicon (polycrystalline Si) film,
As one of the techniques for forming a phosphosilicate glass film (PSG film), a nitride film (SiN film), etc. on the main surface of a semiconductor thin plate (semiconductor wafer or simply called a wafer), a low pressure (decompression) CVD technique is known. Has been. Reduced pressure CV
For D technology, please refer to “Journal of Semiconductor World” published by Press Journal, Inc.
d) ”February 1983 issue, issued January 15, 1983, P40-P48
It is described in. This document describes a hot wall type low pressure CVD apparatus in which a wafer made of a silicon substrate is vertically charged on a quartz boat in a reaction furnace. In this document, SiO by the pressure reduction method is used.
2. The method of forming a PSG film is much more difficult than the method of forming a PolySi or Si3 N4 film. Therefore, it is described that the structure inside the reaction chamber is elaborate. One of the disclosed devices is to mount a BUFFER (buffer) composed of a quartz cylindrical tube on a quartz boat for mounting a wafer. This buffer is provided on the processing gas supply side and is located in the frontmost row of the wafer row that is the object to be processed. The surface of the buffer facing the supplied processing gas is a flat surface, that is, a flat surface orthogonal to the flow direction of the processing gas. Further, another one of the disclosed devices has a structure in which, in addition to the buffer, a quartz porous tube is arranged in the reaction tube, and a quartz boat is arranged in the quartz porous tube. In the case of this reaction chamber, the processing gas is supplied from a plurality of holes provided in the inner wall of the quartz porous tube.

Further, various types of CVD apparatus, that is,
The horizontal type, vertical type, cylindrical type, continuous type, and tubular furnace type are described in "Latest LSI Process Technology" issued by the Industrial Research Committee, January 10, 1991, P227 to P229. Regarding the vertical CVD apparatus, for example, “Electronic Materials” published by the Industrial Research Group, March 1988 issue, March 1, the same year, P57-
P62. The CVD apparatus according to this document is
The vertical diffusion CVD apparatus is provided with an outer tube extending in the longitudinal direction and an inner tube inserted and arranged inside the outer tube. A boat pedestal is arranged below the inner tube, and a wafer boat is mounted on the boat pedestal. The wafers are arranged in the wafer boat so as to sequentially overlap with each other at predetermined intervals from the lower side to the upper side. The gas is sent from below the inner tube, flows while contacting the wafer row, escapes from the hole in the ceiling portion of the inner tube, is guided downward along the outer tube, and is exhausted from the lower part of the outer tube. There is.

[0004]

As described in the above-mentioned document, in the hot wall type low pressure CVD apparatus, a buffer is arranged in the front row of the wafer row in order to adjust the flow of the processing gas, and the CVD processing is performed. There are things that are doing. However, such a buffer causes turbulence,
It was found that the phenomenon of foreign matter adhering to the wafer surface may occur due to the rising of foreign matter due to this turbulent flow. That is, since the buffer is a quartz cylindrical tube whose both end surfaces are flat, the flowing processing gas impinges on the flat surface, and tends to be a turbulent flow. Since this turbulent flow lifts up the foreign matter in the reaction furnace, the lifted foreign matter easily adheres to the wafer surface. Poor adherence of foreign substances not only causes a decrease in film forming yield,
In the photolithography in the subsequent step, the presence of the protrusions due to the adhesion of the foreign matter reduces the yield of contact exposure or causes the failure to form a fine pattern. Further, the turbulent flow causes a disturbance of the flow of the processing gas supplied to the surface of the wafer that stands upright, which causes nonuniformity of the quality and thickness of the CVD film.

An object of the present invention is to provide a chemical vapor deposition (CV) method capable of suppressing foreign matter from adhering to a wafer due to a turbulent flow of a processing gas.
D) To provide a device.

Another object of the present invention is to provide a CVD apparatus capable of achieving uniform quality and thickness of the CVD film.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0008]

The outline of the representative ones of the inventions disclosed in the present application will be briefly described as follows. That is, the low-pressure CVD apparatus of the present invention includes a reaction furnace formed by a cylindrical quartz cylindrical tube extending in the horizontal direction, and a holder for holding a semiconductor wafer which is the object to be processed and is housed in the reaction furnace. (Boat), a gas supply system for feeding a processing gas into the reaction furnace from one end side of the reaction furnace, a gas exhaust system for exhausting a used gas from the other end side of the reaction furnace to the outside of the reaction furnace, and the reaction A low-pressure CVD apparatus having a gas flow adjuster arranged in a furnace and adjusting a flow of a processing gas, wherein two gas flow adjusters are mounted on the boat. The gas flow regulators are arranged in the front row and the rearmost row of the wafer row. The gas flow adjusting body is composed of a main body portion facing the wafer and having a substantially circular shape similar to that of the wafer, and a cone-shaped portion (conical body portion) formed in a continuous manner with the main body portion. There is. The central axis of the conical body portion and the central axis of the circular body portion coincide with each other. Further, the gas flow adjusting body is mounted so that the central axis of the conical body portion is parallel to the boat. Further, the reaction furnace is configured to process the wafer in a low pressure state.

In a low pressure CVD apparatus according to another embodiment of the present invention, the gas flow regulator is fixed to a boat.

[0010]

According to the above-mentioned means, in the low-pressure CVD apparatus of the present invention, since the gas flow adjusting body composed of the conical portion having the pointed tip is disposed in front of the wafer row, the gas supply system is used. The process gas fed into the reactor from one end of the reactor hits the inclined conical surface of the gas flow regulator, and then flows along the conical surface, so that turbulence is less likely to occur and becomes laminar flow. It passes through the conical surface and moves along the inner peripheral surface of a circular quartz cylindrical tube. As a result, it becomes difficult for foreign matter to rise due to the turbulent flow of the processing gas,
A foreign matter adhesion defect in which foreign matter adheres to the wafer surface is less likely to occur.

Further, in the low-pressure CVD apparatus of the present invention, the processing gas is uniformly dispersed over the entire circumference of the quartz cylindrical tube by the gas flow adjusting body composed of the conical portion, and is formed along the longitudinal direction of the quartz cylindrical tube. As a part of the gas flows into the space between the wafers in sequence, the supply of processing gas to each wafer is made uniform, and the quality of the generated CVD film is uniform and the film thickness is uniform. Will be realized.

Further, in the structure in which the gas flow adjusting body according to another embodiment of the present invention is fixed to the boat, the gas flow adjusting body does not move even if a shock is applied to the boat, and the gas flow adjusting body moves. It is possible to prevent the CVD film from becoming non-uniform due to a change in the flow of the processing gas due to (shifting).

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the low-pressure CVD apparatus of the present invention is a horizontal furnace in which an elongated reaction furnace 1 is horizontally extended. The reaction furnace 1 is formed of a quartz cylindrical tube 2,
A wafer (semiconductor wafer) 3, which is an object to be processed, is housed in the furnace. The wafer 3 is placed in a forested state on a holder 4 called a quartz boat. Side walls 5 and 6 are attached to both ends of the reaction furnace 1.

The side wall 5 at the one end serves as a supply side, and a supply pipe 11 for supplying the processing gas 10 into the reaction furnace 1 is attached. A gas supply system 12 for feeding the processing gas 10 into the reaction furnace 1 is formed by the supply pipe 11 and a supply pump, a cylinder, or the like (not shown) connected to the supply pipe 11. A door 13 that can be opened and closed is attached to the side wall 5. The holder (boat) 4 is loaded / unloaded with the door 13 opened.

The side wall 6 at the other end is on the exhaust side,
Exhaust pipe 1 for exhausting used gas 14 such as processing gas 10
5 is attached. In the exhaust pipe 15, gas 1
A main valve (MV) 16, an exhaust pump (P) 17, etc. are attached along the flow direction of 4. Further, the exhaust pipe 15 branches immediately after extending from the reaction furnace 1, and a vent 19 is attached to the branch pipe 18. Although not shown, a vent pump is attached to the end of the vent 19. Therefore, when the vent 19 is opened while the pump for venting is operating, the gas 14 is exhausted to the vent side. In addition, the main valve 16 is provided in the exhaust pipe 15.
A detour pipe 20 that detours around is attached. A sub valve (SV) 21 is attached to the bypass pipe 20. The exhaust pipe 15, the main valve 16, the exhaust pump 17, the branch pipe 18, the vent 19, the bypass pipe 20, the sub valve 21 and the like form a gas exhaust system 22 for exhausting the used gas from the reaction furnace 1.

As shown in FIG. 1, the boat 4 is of a drainboard type so that the processing gas 10 can flow from the lower part of the wafer 3 and has three slits 25 extending along the wafer row. ing. The processing gas 10 that has traveled to the bottom of the boat 4 passes through the slits 25 and enters between the standing wafers 3. As a result, the processing gas 10 can enter the gap between the wafers 3 from the entire circumference of the wafer 3. The wafer 3 is held in a standing state on the boat 4 by being put in a groove (not shown) provided on the upper surface of the boat 4.

On the other hand, this is one of the features of the present invention. A gas flow adjusting body 30 is arranged at the frontmost row and the rearmost row of the wafer row of the boat 4. The gas flow regulator 30 is made of a material having excellent heat resistance and chemical resistance such as quartz or silicon carbide (SiC). The gas flow adjusting body 30 is composed of a cylindrical main body portion 31 having the same diameter as the wafer 3 and a conical portion 32 which is a conical body portion continuous with the main body portion 31. The central axis of the main body portion 31 which is a cylinder and the central axis of the cone-shaped portion 32 which is a conical body portion are coincident with each other. The gas flow regulator 3
0 is the boat 4 so that the body portion 31 can be laid down.
Placed on top. As a result, the central axis of the conical portion 32 coincides with the center of the wafer 3 and is parallel to the plane of the boat 4. The gas flow adjusting body 30 is arranged such that the apexes 33 of the conical portions 32 are located on the side walls 5 and 6, respectively. As a result, due to the action of the conical surface of the conical portion 32, on the gas supply side, the flowing processing gas 10 is uniformly dispersed over the entire inner wall of the quartz cylindrical tube 2 without causing a turbulent flow, and the gas is exhausted. On the side, the exhaust gas pipe 15 collects the used gas 14 such as the processing gas 10 flowing along the entire circumference of the inner wall of the quartz cylindrical pipe 2 without causing a turbulent flow.
Will be focused on.

On the other hand, a heater 40 is arranged on the outer peripheral side of the reaction furnace 1 to heat the inside of the reaction furnace 1 to a predetermined temperature. Further, the CVD apparatus of the present invention is a low pressure CVD apparatus capable of reducing the pressure in the reaction furnace 1 to, for example, about 0.5 torr by operating the exhaust pump 17.

Next, an example of forming a nitride film (Si3 N4 film) on the surface of the wafer will be described. The wafer 3 is placed on the boat 4 in a forested state. Further, as shown in FIG. 1, the gas flow regulator 30 is placed on the boat 4 before and after the wafer row. The apex 33 of the cone-shaped portion 32 of each gas flow adjuster 30 is located outside on the extension of the wafer row. The boat 4 on which the wafer 3 is placed is placed in the reaction furnace 1. Since the reactor 1 is heated by the heater 40, after the boat 4 is inserted and the door 13 is closed, the temperature inside the reactor is gradually increased and set to a desired temperature between 770 and 830 ° C.

After the door 13 is closed, the gas exhaust system 22 is activated. In this exhaust, only the sub-valve 21 with a low flow rate is opened first. This is to prevent turbulence from occurring in the reaction furnace 1 when abruptly exhausting air and to wind up foreign matter. Sub valve 21
Is opened, and after a predetermined time has passed, for example, 5 minutes later, the main valve 16 is opened. Main valve 16 and sub valve 2
By opening 1, the pressure in the reaction furnace 1 is gradually reduced, and is reduced to the processing pressure of about 0.5 torr.

In this state, the gas supply system 12 operates to supply the processing gas 10 into the reaction furnace 1 through the supply pipe 11. As the processing gas 10, SiH2 Cl2 and NH3 are used. As a result, the Si3 N
4 A film will be formed. At the time of forming this Si3 N4 film, since the gas flow adjusting body 30 having a conical tip portion is arranged in front of the wafer row, the processing gas 10 hitting the conical portion is turbulent due to the conical surface. Without being caused, it is uniformly dispersed on the entire inner wall of the quartz cylindrical tube 2. Therefore, the foreign matter can be prevented from being rolled up (raised) due to the turbulent flow, and the occurrence of defects due to the foreign matter attached to the wafer surface can be prevented.

The processing gas 10 dispersed on the entire inner wall of the quartz cylindrical tube 2 flows as a laminar flow along the inner wall of the quartz cylindrical tube 2. Further, the gas portion inside the processing gas 10 that flows as a laminar flow along the inner wall of the quartz cylindrical tube 2 flows into the gap 41 between the wafer 3 and the wafer 3. Therefore, since the processing gas 10 is sequentially supplied from the entire circumference toward the center of the surface of the circular wafer 3, a CVD film having a uniform and uniform thickness is formed.

A gas flow adjusting body 30 is arranged at the end of the wafer row. Since the apex 33 of the cone-shaped portion 32 is arranged so that the apex 33 of the cone-shaped portion 32 faces the exhaust side, the gas flow adjusting body 30 has the processing gas 10 and the used gas flowing along the inner wall of the quartz cylindrical tube 2. 14 is a cone-shaped portion 32
Since it flows toward the central portion of the quartz cylindrical tube 2 along the conical surface of, the turbulent flow does not occur, and the CVD film can be well formed on the wafer 3 at the rear of the wafer row, and the CVD film has a uniform and uniform thickness. It becomes

After the CVD film is formed, the supply of the processing gas 10 is stopped and the nitrogen gas is supplied. Then, the vent 19 of the gas exhaust system 22 is opened, and the main valve 16 and the sub valve 21 are closed. When the pressure inside the reaction furnace 1 becomes normal pressure, the door 13 is opened and the boat 4 is taken out. This completes one CVD process.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say, for example,
As shown in FIG. 3, the gas flow regulator 30 is attached to the boat 4
If formed integrally with, the gas flow regulator 30 does not move even when a shock is applied to the boat 4, and is caused by a change in the flow of the processing gas 10 due to the gas flow regulator 30 moving (shifting). It is possible to prevent the CVD film from becoming non-uniform.
By integrating the gas flow regulator 30 with the boat 4, the main body portion 31 of the gas flow regulator 30 can be thinned. That is, the columnar part is unnecessary.

In the embodiment, the gas flow adjusting body 30 has a conical structure, but it may have a pyramidal shape. Further, the wafer 3 has a shape in which one edge thereof is linearly cut (orientation flat), but one edge of the gas flow adjusting body 30 is cut out so as to fit the orientation flat. You may stay. In this case, the flow of the processing gas 10 surely becomes a laminar flow in the orientation flat portion.

FIG. 4 shows an application of the present invention to a vertical low pressure CVD apparatus. Vertical low pressure CVD reactor 50
Has a vertically long (height direction) long structure, and has an outer tube 51 extending vertically in the reaction furnace 50, and an inner tube 52 arranged inside the outer tube 51. . A boat pedestal 53 is disposed below the inner tube 52.
A boat (holding tool) 54 is attached on the top. The wafers 3 are arranged in the boat 54 so as to sequentially overlap with each other from the lower side to the upper side at predetermined intervals. The processing gas 10 is fed from below the inner tube 52 and flows while contacting the wafer row,
The structure is such that it is pulled out from the ceiling part of 2, and is guided downward along the outer tube 51, and is exhausted from the lower part of the outer tube 51.

In such a vertical type low pressure CVD apparatus,
As shown in FIG. 5, gas flow regulators 30 are arranged on the gas supply side and the gas exhaust side of the boat 54, that is, before and after the wafer row. In this example, the gas flow regulator 30 is integrated with the boat 4. Boat 54
It has a pair of support plates 55 and 56 facing each other.
Grooves for accommodating the wafer 3 are provided substantially horizontally on the inner surfaces of 5, 56. Therefore, the wafer 3 is inserted between the support plates 55 and 56 in the horizontal direction. In addition, the support plate 5
Slits and holes through which the processing gas 10 can freely pass are provided at positions 5 and 56.

Also in the case of this embodiment, as in the previous embodiment, the turbulent flow generation is suppressed on the supply side and exhaust side of the processing gas by the action of the conical surface of the conical portion 32 of the gas flow adjusting body 30. It is possible to prevent foreign matter contamination of the wafer due to the rising of foreign matter. Further, due to the action of the conical surface of the gas flow adjusting body 30, the processing gas 10 is uniformly dispersed all around the inner wall of the inner tube 52 and flows as a laminar flow.
The CVD film formed on the surface of the wafer 3 has a uniform and uniform thickness.

In the above description, the invention made mainly by the present inventor is a low-pressure C which is the field of application behind the invention.
The case where the invention is applied to the VD device has been described, but the invention is not limited thereto. The present invention is applicable to at least a chemical vapor deposition apparatus.

[0031]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows. In the low-pressure CVD apparatus of the present invention, gas flow regulators are arranged in front of and behind the wafer row. The gas flow regulator has a cone portion having a sharp tip, and the cone portion is processed on the gas supply side. Since the gas is dispersed as a laminar flow all around the inner wall of the quartz cylindrical tube, turbulent flow does not occur, foreign particles do not rise, and defective adhesion of foreign matter to the wafer can be prevented. Further, on the gas exhaust side as well, the conical portion can prevent the turbulent flow of the exhaust gas, and the flow of the processing gas on the exhaust side becomes a laminar flow without being disturbed and advances along the outer periphery of the wafer. As a result, the CVD film formed on the wafer surface has a uniform and uniform thickness.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main part of a low pressure CVD apparatus according to the present invention.

FIG. 2 is a perspective view showing a boat, a buffer and the like in the low pressure CVD apparatus of this embodiment.

FIG. 3 is a cross-sectional view showing a boat, a buffer and the like according to a modified example of the low pressure CVD apparatus of this embodiment.

FIG. 4 is a sectional view showing a main part of a vertical low pressure CVD apparatus according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view of essential parts showing a boat in a vertical low pressure CVD apparatus according to another embodiment of the present invention.

[Explanation of Codes] 1 ... Reactor, 2 ... Quartz cylindrical tube, 3 ... Wafer, 4 ... Holder (boat), 5, 6 ... Side wall, 10 ... Processing gas, 11 ... Supply pipe, 12 ... Gas supply system, 13 ... Door, 14 ... Gas, 15 ... Exhaust pipe, 16 ... Main valve, 17 ... Exhaust pump, 18 ... Branch pipe, 19 ... Vent, 20 ... Detour pipe, 2
1 ... Sub valve, 22 ... Gas exhaust system, 25 ... Slit,
30 ... Gas flow adjuster, 31 ... Main body part, 32 ... Conical part, 33 ... Apex, 40 ... Heater, 50 ... Reactor, 51
... Outer tube, 52 ... Inner tube, 53 ... Boat cradle, 54 ... Boat, 55, 56 ... Support plate.

Claims (5)

[Claims] 1. A reaction furnace, a holder that is housed in the reaction furnace and holds an object to be processed, a gas supply system that sends a processing gas into the reaction furnace, and a used gas from the reaction furnace. A chemical vapor deposition apparatus having a gas exhaust system for exhausting gas, and a gas flow adjuster arranged in the reaction furnace for adjusting the flow of a processing gas, wherein the gas flow adjustor is the object to be treated. A chemical vapor deposition apparatus comprising: a main body part facing the substrate and having substantially the same shape as the object to be processed; and a conical part having a sharp tip formed in a continuous manner with the main body part. . 2. A reaction furnace, a holder that is housed in the reaction furnace and holds an object to be processed, a gas supply system that sends a processing gas into the reaction furnace, and a used gas from the reaction furnace. A chemical vapor deposition apparatus having a gas exhaust system for exhausting gas, and a gas flow adjuster arranged in the reaction furnace for adjusting the flow of a processing gas, wherein the gas flow adjustor is the object to be treated. And a main body portion having a substantially same shape as that of the object to be processed, and a conical portion having a sharp tip formed in a continuous manner with the main body portion, and are provided in front of and behind the row of objects to be processed. A chemical vapor deposition apparatus characterized in that 3. A reaction furnace, a holder that is housed in the reaction furnace and holds an object to be processed, a gas supply system that sends a processing gas into the reaction furnace, and a used gas from the reaction furnace. A chemical vapor deposition apparatus having a gas exhaust system for exhausting gas, and a gas flow adjuster arranged in the reaction furnace for adjusting the flow of a processing gas, wherein the gas flow adjustor is the object to be treated. Characterized in that it is composed of a main body portion that faces the workpiece and has substantially the same shape as the object to be processed, and a cone-shaped portion that is formed in a continuous manner with the main body portion and has a sharp tip, and that it is fixed to the holder. And chemical vapor deposition equipment. 4. A reaction furnace, a holder that is housed in the reaction furnace and holds an object to be processed, a gas supply system that feeds a processing gas into the reaction furnace, and a used gas from the reaction furnace. A chemical vapor deposition apparatus having a gas exhaust system for exhausting gas, and a gas flow adjuster arranged in the reaction furnace for adjusting the flow of a processing gas, wherein the gas flow adjustor is the object to be treated. And a main body portion having a substantially same shape as that of the object to be processed, and a conical portion having a sharp tip formed in a continuous manner with the main body portion, and are provided in front of and behind the row of objects to be processed. The low pressure chemical vapor deposition apparatus is characterized in that the reaction furnace is configured to process the object to be processed in a low pressure state. 5. A holder which is placed in a reaction furnace of a chemical vapor deposition apparatus and on which a plurality of objects to be processed are placed in a forest, wherein a gas flow regulator is provided before and after the object row of the objects of the holder. A holding tool characterized by being fixed.