JPH07183221A - Polygonal susceptor type vapor phase growth system - Google Patents

Abstract

(57) [Summary] [Object] To provide a polygonal susceptor type vapor phase growth apparatus capable of reducing variations in film thickness on a wafer. [Structure] The polygonal susceptor 2 is provided in the reactor 1 so as not to revolve. A raw material gas supply port for supplying a raw material gas to each flat surface portion 2 a of the polygonal susceptor 2 is provided on one end side of the reactor 1. On each flat surface portion 2a of the polygonal susceptor 2, a rotation tray 4 that supports the wafer 3 is rotatably supported on the polygonal susceptor 2. A tray rotation drive mechanism 30 for rotating the rotation tray 4 is connected to the rotation tray 4. Inside the reactor 1, a polygonal inner tube 37 having a flat surface portion 37 a facing each flat surface portion 2 a of the polygonal susceptor 2 is arranged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polygonal susceptor type vapor phase growth apparatus for rotating a tray supported by a polygonal susceptor in a reactor and performing vapor phase growth on a wafer on the tray. Is.

[0002]

2. Description of the Related Art GaAs is formed on the surface of a susceptor in a reactor.
The wafer is supported, and the susceptor is held at, for example, 600 ° C to 800 ° C.
Of AsH ₃ (arsine), TMG (trimethylgallium), and TMAl in a state of being heated to the high temperature of
An epitaxial wafer formed by flowing a source gas such as (trimethylaluminum) together with a carrier gas made of hydrogen and epitaxially growing the GaAs wafer is
It is used as a material for FETs and HEMT devices for satellite broadcasting and mobile phones.

In order to reduce the cost, it is advantageous to place a large number of wafers on the susceptor and perform the vapor phase growth process. Therefore, a barrel type polygonal susceptor is used as the susceptor.

In recent years, it has been required to increase the amount of the epitaxial wafer used and to improve the quality. Among the qualities, the uniformity of film thickness and the uniformity of carrier concentration are important.

In order to improve such quality, a polygonal susceptor type vapor phase growth apparatus as shown in FIG. 9 has been proposed. In this polygonal susceptor type vapor phase growth apparatus, a barrel-shaped polygonal susceptor 2 is provided in a reactor 1 having a circular cross section, and the polygonal susceptor 2 is revolved around its axis by a susceptor support shaft (not shown). A raw material gas supply port (not shown) for supplying a raw material gas to each flat surface portion 2a of the polygonal susceptor 2 is provided at an upper end of the reactor 1, and the flat surface portion 2a of the polygonal susceptor 2 is supported. A rotation tray 4 that supports the wafer 3 is rotatably supported by the polygonal susceptor 2, and a tray rotation drive mechanism (not shown) is connected to the rotation tray 4 to rotate the rotation tray 4.

[0006] In such a polygonal susceptor type vapor phase growth apparatus, since the polygonal susceptor 2 is revolved and the rotating tray 4 is rotated on the polygonal susceptor 2, each flat surface portion 2a of the polygonal susceptor 2 is rotated. There is no directionality of the flow of the raw material gas with respect to the surface of each wafer 3 on each rotation tray 4 in the above, and the conditions for contacting the raw material gas are almost uniform, the thin film growth can be made uniform, and the quality of the obtained epitaxial wafer is improved. Can be achieved.

The variation in the film thickness of the epitaxial wafer obtained by this apparatus is ± 3 to 4%, which is different from the variation in the film thickness of the epitaxial wafer in the case of the revolution type apparatus being ± 5 to 7%. Have been improved.

[0008]

However, in such a conventional polygonal susceptor type vapor phase growth apparatus,
Since the polygonal susceptor 2 is provided in the reactor 1 having a circular cross section, the distance between the flat surface portion 2a of the polygonal susceptor 2 and the reactor 1 is as shown in FIG.
The distance a is different between the distance a at the center of the plane portion 2a and the distance b at the ends, so that the variation in the film thickness on the wafer 3 can be reduced to ± 3% or less as shown in FIG. Therefore, there is a problem that the request of the user requesting about ± 2% cannot be answered.

An object of the present invention is to provide a polygonal susceptor type vapor phase growth apparatus capable of reducing variations in film thickness on a wafer.

[0010]

The constitution of the present invention which achieves the above object will be described as follows.

The polygonal susceptor type vapor phase growth apparatus according to claim 1 is provided in the reactor so that the polygonal susceptor does not revolve, and one end of the reactor is provided with a raw material on each flat surface portion of the polygonal susceptor. A raw material gas supply port for supplying gas is provided, and a rotating tray for supporting a wafer is rotatably supported on each of the plane portions of the polygonal susceptor, and the rotation tray rotates the tray. The tray rotation drive mechanism is connected, and a polygonal inner tube having a flat surface portion facing each flat surface portion of the polygonal susceptor is arranged in the reactor.

A polygonal susceptor type vapor phase growth apparatus according to a second aspect is the polygonal susceptor type vapor phase growth apparatus according to the first aspect, wherein a partition is disposed at a position where each corner of the polygonal susceptor and the polygonal inner tube faces each other. It is characterized by being

[0013]

According to the first aspect of the present invention, the polygonal susceptor is arranged in the reactor so as not to revolve, and the polygonal inner has a flat surface portion facing each flat surface portion of the polygonal susceptor in the reactor. When the tubes are arranged, the distance between each flat surface portion of the polygonal susceptor and each flat surface portion of the polygonal inner tube becomes substantially constant at each position in the flow direction of the raw material gas and in the direction orthogonal to the flow direction. Since the rotation tray supporting the wafer is rotated on each flat surface of the polygonal susceptor, the thin film growth can be made uniform, and the variation in the thickness of the obtained epitaxial wafer can be reduced to the extent required by the user.

Further, when the distance between each flat surface portion of the polygonal susceptor and each flat surface portion of the polygonal inner tube becomes substantially constant at each position in the flow direction of the raw material gas in the direction orthogonal to the flow direction, the raw material When the gas is switched, the switching of the gas is accelerated, which improves the steepness of the film interface of the epitaxial wafer.

As in the invention described in claim 2, when the partition bodies are arranged at the opposite positions of the respective corners of the polygonal susceptor and the polygonal inner tube, mutual influence on the adjacent flat surface side of the polygonal susceptor is prevented. It is possible to avoid the vapor phase growth and to further reduce the variation in the film thickness of the epitaxial wafer.

[0016]

1 to 3 show a polygonal susceptor type vapor phase growth apparatus according to a first embodiment of the present invention. The polygonal susceptor type vapor phase growth apparatus of this embodiment includes a reactor 1 having a circular cross section, and the reactor 1 is made of a non-metal material such as quartz glass which is hard to be induction-heated and to generate impure gas. It is composed of a main body 5 and a chamber 6 made of metal such as stainless steel, which is provided below the main body 5. In the middle of the reactor main body 5 in the vertical direction, the expanded diameter step 5
a is provided, and the reactor main body portion 5 below the expanded diameter step portion 5a is expanded in diameter from the upper portion. A source gas supply port 7 is provided above the reactor body 5. Corresponding to the raw material gas supply port 7, a raw material gas blowing projection 8 is provided above the reactor main body 5 so as to project into the reactor main body 5. The raw material gas blowing projection 8 is provided with a plurality of raw material gas blowing holes 8a.

A hexagonal polygonal susceptor 2 made of a material such as carbon which is easily heated by induction is disposed in the reactor body 5. The polygonal susceptor 2 is supported by a susceptor support shaft 9. At least the upper portion of the susceptor support shaft 9 needs to be formed of a non-metal such as quartz glass, but the lower portion can be formed of a metal such as stainless steel. A receiving portion 10 is provided at the tip of the susceptor supporting shaft 9, and the receiving portion 10 is provided on the lower surface of the polygonal susceptor 2.
1, the polygonal susceptor 2 is attached to the susceptor support shaft 9
Supported by. The lower portion of the susceptor support shaft 9 penetrates the bottom surface of the chamber portion 6 of the reactor 1.

A hole 13 is formed in the shaft center of the susceptor support shaft 9 so that a lead wire of a temperature sensor such as a thermocouple (not shown) provided on the lower surface of the polygonal susceptor 2 can be passed through the hole 13. It has become.

A susceptor elevating mechanism 14 for elevating the polygonal susceptor 2 via a susceptor support shaft 9 is provided below the chamber portion 6 as shown in FIG. The susceptor elevating mechanism 14 has an elevating bracket 15 that supports the susceptor support shaft 9, an elevating guide 16 that guides the elevating bracket 15 while preventing it from rotating, and a rotative movement that is penetrated by the elevating bracket 15 with a screw coupling portion. Is converted into a linear motion by the screw coupling part and applied to the elevating bracket 15, and a motor (not shown) that rotates the screw 17.

A concave portion 18 is provided in each flat surface portion 2a of the polygonal susceptor 2, and a rotating tray 4 made of carbon or the like for supporting the wafer 3 is rotatably supported in the concave portion 18. A tray rotation shaft 19 made of carbon or the like for transmitting a rotational force to the rotation tray 4 is rotatably penetrating the polygonal susceptor 2 and led out to a gear chamber 20 on the rear surface side. At the end of the tray rotation shaft 19 led out to the back side of the polygonal susceptor 2, a tray rotation planetary gear 21 made of quartz glass or the like is provided.
Is installed.

On the outer periphery of the upper shaft portion of the susceptor support shaft 9, a sun gear 22 made of carbon or the like that meshes with the tray rotation planetary gear 21 is coaxially arranged. Susceptor support shaft 9
A cylindrical sun gear support 23 is coaxially arranged on the outer periphery of the. The sun gear support 23 is composed of an upper support part 23a made of a non-metal such as quartz glass and a lower support part 23b made of a metal such as stainless steel. The sun gear 22 is supported on the upper end of the upper support portion 23 a of the sun gear support 23. The sun gear support 23
A bearing 24 is interposed between the lower support portion 23b and the susceptor support shaft 9.

Lower support portion 23 of the sun gear support 23
b penetrates the bottom surface of the chamber portion 6 of the reactor 1 via the seal portion 25. A seal portion 26 is also provided between the lower support portion 23b of the sun gear support 23 and the susceptor support shaft 9.

A gear 27 is attached to the outer periphery of the lower support portion 23b protruding from the bottom surface of the chamber portion 6, and a gear 28 is meshed with the gear 27. The gear 28
Are rotated by a motor 29.

These tray rotation shaft 19, tray rotation planetary gear 21, sun gear 22, sun gear support 23, gear 2
A tray rotation drive mechanism 30 configured to rotate the rotation tray 4 by the 7, gear 28, and motor 29 is configured.

On the upper portion of the polygonal susceptor 2, a cap 31 having a circular cross section is installed. A cap recess 32 into which the raw material gas blowing projection 8 is fitted is provided on the top of the cap 31.
And a gas flow path 33 is formed in the cap recess 32 along the surface of the raw material gas blowing projection 8.

An exhaust port 34 is provided in the chamber portion 6 adjacent to the lower portion of the reactor main body portion 5. A flow guide 35 for guiding the exhaust gas descending from the inside of the reactor main body 5 to the exhaust port 34 side is provided on the outer periphery of the upper support portion 23a of the sun gear support 23 corresponding to the exhaust port 34.
Is provided.

A high frequency heating coil 36 as a heater for heating the polygonal susceptor 2 is provided on the outer circumference of the reactor main body 5.
Are arranged.

In particular, inside the enlarged diameter portion of the reactor main body 5 below the enlarged diameter step portion 5a of the reactor main body portion 5, a polygonal inner having a flat surface portion 37a facing each flat surface portion 2a of the polygonal susceptor 2. The tube 37 has its upper end expanded-diameter step 5a
The lower end of the chamber 6 and the flange 3 at the upper end of the chamber 6.
The inner tube holder 39 provided in FIG. The polygonal inner tube 37 is made of quartz glass or the like.

Reference numeral 50 is a skirt portion for gas rectification provided under the polygonal susceptor 2 and on the outer periphery of the upper support portion 23a.

In such a polygonal susceptor type vapor phase growth apparatus, the motor 29 of the tray rotation drive mechanism 30 is driven to rotate the rotation tray 4 together with the wafer 3 without rotating the polygonal susceptor 2.

A raw material gas is supplied into the reactor main body 5 from a raw material gas supply port 7 provided above the main body 5. The raw material gas supplied to the raw material gas supply port 7 is blown into the cap recess 32 from the raw material gas blowing hole 8 a of the raw material gas blowing projection 8 and flows down uniformly over the entire circumference of the surface of the cap 31. . For this reason, the source gas can be made to flow uniformly to each flat surface portion 2a without revolving the polygonal susceptor 2.

On the other hand, the polygonal susceptor 2 is heated to, for example, 600 to 800 ° C. by the high frequency heating coil 36, so that the wafer 3 is heated. At this time, the temperature of the polygonal susceptor 2 is measured by a temperature sensor (not shown), and the energization of the high frequency heating coil 36 is controlled to control the temperature of the polygonal susceptor 2 to be constant.

When the source gas flows on the heated surface of the wafer 3, vapor phase growth is performed on the surface of the wafer 3 to obtain an epitaxial wafer.

At this time, since the polygonal inner tube 37 having the flat surface portion 37a facing each flat surface portion 2a of the polygonal susceptor 2 is arranged in the reactor main body portion 5, each of the polygonal susceptor 2 is arranged. The distance between the flat surface portion 2a and each flat surface portion 37a of the polygonal inner tube 37 is substantially constant in each position in the flow direction of the source gas in the direction orthogonal to the flow direction, and moreover, the rotation tray supporting the wafer 3 is provided. 4 is rotated on each flat surface portion 2a of the polygonal susceptor 2, thin film growth can be made uniform, and the variation in film thickness of the obtained epitaxial wafer is about ± 2% required by the user as shown in FIG. Could be reduced to.

The distance between each flat surface portion 2a of the polygonal susceptor 2 and each flat surface portion 37a of the polygonal inner tube 37 is substantially constant at each position in the flow direction of the source gas and in the direction orthogonal to the flow direction. In this case, the gas switching becomes quicker when the source gas is switched, so that the steepness of the interface of the film of the epitaxial wafer is improved.

To attach and detach the wafer 3 on the polygonal susceptor 2,
The polygonal susceptor 2 is moved down into the chamber 6 by driving the susceptor lifting mechanism 14.

At the time of attaching and detaching the wafer 3 as described above, it is preferable that the polygonal inner tube 37 is also attached and detached and replaced with a cleaned one. If the polygonal inner tube 37 is long and inconvenient to attach and detach, the polygonal inner tube 37 may be divided into upper and lower structures.

FIG. 5 and FIG. 6 show a second embodiment of the polygonal susceptor type vapor phase growth apparatus according to the present invention.
In the polygonal susceptor type vapor phase growth apparatus of this embodiment, the inner tube holder 39 supporting the lower end of the polygonal inner tube 37 has a skirt portion 50 on the sun gear support 23 side.
(When there is no skirt portion 50, the upper support portion 23a)
The feature is that it is provided in. In this case, the inner tube holder 39 is formed in a radial shape, and an exhaust gap 40 is radially formed between the inner tube holder 39 and the inner tube 37.
The exhaust gas descending inside passes through the exhaust gap 40 and the exhaust port 3
It is designed to exhaust to the 4 side. In this case, the upper end of the inner tube holder 39 is in contact with the upper shoulder of the reactor body 5.

With this structure, when the polygonal susceptor 2 is moved up and down, the polygonal inner tube 37 can be moved up and down together. In this way, the dirty polygonal inner tube 37 can be easily replaced.

FIG. 7 shows a third embodiment of a polygonal susceptor type vapor phase growth apparatus according to the present invention. The polygonal susceptor type vapor phase growth apparatus of this embodiment is characterized in that the flow guide 35 for guiding the exhaust gas to the exhaust port 34 also serves as an inner tube holder that supports the lower end of the polygonal inner tube 37. Along with this, an exhaust port 41 is provided below the polygonal inner tube 37.

With such a structure, it is not necessary to provide the inner tube holder 39 having a special structure.

Also in this structure, when the polygonal susceptor 2 is moved up and down, the polygonal inner tube 37 can be moved up and down together, and the dirty polygonal inner tube 3 can be moved.
7 can be easily replaced.

FIG. 8 shows a fourth embodiment of the polygonal susceptor type vapor phase growth apparatus according to the present invention. In the polygonal susceptor type vapor phase growth apparatus according to the present embodiment, the partition body 4 having protrusions on the inner surface of each corner of the polygonal inner tube 37.
1 shows an example in which 1 is projected.

The partition body 41 may be provided so as to project at each corner of the polygonal susceptor 2. Alternatively, the partition body 41 can be provided so as to project at both corners of the polygonal inner tube 37 and at each corner of the polygonal susceptor 2.

As described above, the partition member 4 is provided at a position where the corners of the polygonal susceptor 2 and the polygonal inner tube 37 face each other.
By disposing No. 1, it is possible to avoid mutual influences on the adjacent flat surface portions 2a side of the polygonal susceptor 2 and to perform vapor phase growth, and further reduce the variation in film thickness of the epitaxial wafer.

In each of the above embodiments, the polygonal susceptor 2 and the polygonal inner tube 37 are hexagonal. However, the present invention is not limited to this, and it is needless to say that they may be octagonal or the like.

Further, the structure in which the raw material gas blowing projection 8 communicating with the raw material gas supply port 7 is provided in the upper portion of the reactor main body 5 and the cap concave portion 32 is provided in the cap 31 is not limited to the second embodiment. ~ The same can be applied to the fourth embodiment.

By doing so, even if the polygonal susceptor 2 and the cap 31 are slightly eccentric in the reactor main body 5, the raw material gas can be made to flow uniformly to each flat surface 2a of the polygonal susceptor 2. The disadvantage of not revolving the polygonal susceptor 2 can be eliminated.

[0049]

As described above, the polygonal susceptor type vapor phase growth apparatus according to the present invention can achieve the following excellent effects.

According to the first aspect of the invention, the polygonal susceptor is arranged in the reactor so as not to revolve, and the polygonal inner tube having the flat surface portion facing each flat surface portion of the polygonal susceptor is provided in the reactor. Since they are arranged, the distance between each flat surface portion of the polygonal susceptor and each flat surface portion of the polygonal inner tube should be substantially constant at each position in the flow direction of the raw material gas and in the direction orthogonal to the flow direction. In addition, since the rotation tray supporting the wafer is rotated on each flat surface of the polygonal susceptor, thin film growth can be made uniform, and the variation in the thickness of the obtained epitaxial wafer can be reduced to the degree required by the user. be able to.

Further, according to the present invention, it is possible to improve the characteristics and simultaneously improve the steepness of the interface of the film of the epitaxial wafer. As a result, the yield of the epitaxial wafer can be improved by the film forming and etching steps in the subsequent steps.

According to the second aspect of the present invention, since the partition bodies are arranged at the positions where the corners of the polygonal susceptor and the polygonal inner tube face each other, mutual influences on the adjacent flat surface side of the polygonal susceptor. The vapor phase growth can be performed while avoiding the above, and the variation in the film thickness of the epitaxial wafer can be further reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an example of an upper structure of a first embodiment of a polygonal susceptor type vapor phase growth apparatus according to the present invention.

FIG. 2 is a vertical cross-sectional view showing an example of the lower structure of the first embodiment of the polygonal susceptor type vapor phase growth apparatus according to the present invention.

FIG. 3 is a cross-sectional view showing an arrangement state of a polygonal susceptor and a polygonal inner tube used in this embodiment.

FIG. 4 is a diagram showing a film thickness distribution of an epitaxial wafer manufactured by the polygonal susceptor type vapor phase growth apparatus of this example.

FIG. 5 is a vertical cross-sectional view showing an example of the upper structure of the second embodiment of the polygonal susceptor type vapor phase growth apparatus according to the present invention.

6 is a cross-sectional view showing the structure of the inner tube holder of FIG.

FIG. 7 is a vertical cross-sectional view showing an example of the upper structure of the third embodiment of the polygonal susceptor type vapor phase growth apparatus according to the present invention.

FIG. 8 is a lateral cross-sectional view of a main part showing a fourth embodiment of a polygonal susceptor type vapor phase growth apparatus according to the present invention.

FIG. 9 is a cross-sectional view showing the configuration of the main part of a conventional polygonal susceptor type vapor phase growth apparatus.

10 is a cross-sectional view of essential parts showing the relationship between the polygonal susceptor and the reactor in the conventional apparatus shown in FIG.

FIG. 11 is a diagram showing a film thickness distribution of an epitaxial wafer manufactured by a conventional polygonal susceptor type vapor phase growth apparatus.

[Explanation of symbols]

 1 Reactor 2 Polygonal susceptor 2a Flat part 3 Wafer 4 Rotating tray 5 Reactor body part 5a Expanding step part 6 Chamber part 7 Raw material gas supply port 8 Raw material gas blowing projection 8a Raw material gas blowing hole 9 Susceptor support shaft 10 Receiving part 11 Projection 13 Hole 14 Susceptor Lifting Mechanism 15 Lifting Bracket 16 Lifting Guide 17 Screw 18 Recess 19 Tray Rotating Shaft 20 Gear Chamber 21 Tray Rotating Planetary Gear 22 Sun Gear 23 Sun Gear Support 23a Upper Support 23b Lower Support 24 Bearing 25, 26 Seal part 27, 28 Gear 29 Motor 30 Tray rotation drive mechanism 31 Cap 32 Cap recess 33 Gas flow path 34 Exhaust port 35 Flow guide 36 High frequency heating coil 37 Polygonal inner tube 37a Flat part 38 Flange 39 Inner tube ho Da 40 exhaust gap 41 outlet 50 skirt

Claims (2)

[Claims] 1. A polygonal susceptor is provided in the reactor so as not to revolve, and a raw material gas supply port for supplying a raw material gas to each flat surface portion of the polygonal susceptor is provided at one end of the reactor. A rotation tray for supporting a wafer is rotatably supported on the polygonal susceptor on each flat surface of the rectangular susceptor, and a tray rotation drive mechanism for rotating the rotation tray is connected to the rotation tray. A polygonal susceptor type vapor phase growth apparatus, wherein a polygonal inner tube having a flat surface portion facing each flat surface portion of the polygonal susceptor is arranged. 2. The polygonal susceptor type vapor phase epitaxy according to claim 1, wherein a partition body is disposed at a position where each corner of the polygonal susceptor and the polygonal inner tube faces each other. apparatus.