JPH08306630A - Vapor growth equipment - Google Patents

Abstract

PURPOSE: To provide a vapor growth equipment wherein irregularity of film thickness of epitaxial wafers formed on the respective surfaces of a barrel type susceptor, irregularity of concentration of carrier gas, and irregularity between the respective surfaces of the susceptor are reduced. CONSTITUTION: This vapor growth equipment is provided with a reactor 20, a barrel type susceptor 10 on which wafers 12 are mounted, material supplying ports which introduce material gas to the inside of the reactor 20, and an exhaust vent 32 which discharges exhaust gas of the material gas introduced in the inside of the reactor 20, to the outside of the reactor 20. A number of the material supplying ports P1 -Pn , which number corresponds to the number of surfaces of the barrel type susceptor 10 on which surfaces the wafers 12 are mounted, are arranged above the reactor 20 at specified intervals corresponding to a surface 13. A discharging ring 31 continuously connected to the exhaust vent 32 is installed in the lower part in the reactor 20, and the barrel type susceptor 10 and the discharging ring 31 are relatively rotated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor phase growth apparatus for forming an epitaxial wafer such as a III-V group compound semiconductor, and more particularly to a vapor phase growth apparatus having a barrel type susceptor.

[0002]

2. Description of the Related Art In recent years, satellite broadcasting, mobile phones and the like have become widespread, and an epitaxial wafer by a vapor phase growth apparatus has been attracting attention as a material of an electronic device used for them. With the expansion of this market, the production of epitaxial wafers by vapor phase growth equipment is 2 "x 6 → 2" x 9 → 3 "x 6 → 3" x
As the outer diameter of the epitaxial wafer is increased from 12 to 4 ″ × 6, the number is also increased.

An example of a conventional vapor phase growth apparatus for forming this epitaxial wafer is shown in FIG. The conventional vapor phase growth apparatus 50 of FIG. 6 is supported by a vertical rotation shaft 56, and a plurality of GaAs wafers 52 are mounted on a barrel type susceptor 51 that revolves around the whole.
And the raw material gas is supplied from a nozzle 54 provided at the top of the reactor 53. The raw material gas is supplied as a gas flow, and is deposited on the GaAs wafer 52 by a gas phase reaction or a thermal decomposition reaction on the surface of the GaAs wafer 52 heated to a predetermined temperature by heating means such as high frequency induction heating or resistance heating. After the epitaxial film is formed, it is discharged from the exhaust port 55 below the reactor 53. There are various specifications of the epitaxial wafer formed by the vapor phase growth apparatus,
The variation in the film thickness uniformity of the epitaxial film is about ± 5% within and between the wafer surfaces, and the variation in the carrier gas concentration is also about ± 5%.

[0004]

Therefore, various improvements have been made in order to reduce these variations. Among them, the method of rotating the wafer along with the revolution is ± 3% in the in-plane film thickness variation of the epitaxial wafer formed on each surface of the barrel-type susceptor, and ± ± in the carrier gas concentration variation.
3%. However, in this method, the variation between the surfaces of the susceptor remains ± 5% and is not improved.

The main cause of this is that the axis of the susceptor is tilted with respect to the vertical rotation axis. The flow of the source gas on each surface is non-uniform. The temperature of the susceptor may differ between the surfaces.

The present invention solves the above problems and provides a vapor phase growth apparatus for reducing variations in film thickness of an epitaxial wafer formed on each surface of a barrel type susceptor, variations in carrier gas concentration, and variations between surfaces of a susceptor. It is intended to be provided.

[0007]

The present invention has the following means in order to solve the above problems.

The vapor phase growth apparatus according to claim 1 of the present invention is
A reactor, a barrel type susceptor for mounting a wafer arranged inside the reactor, a raw material supply port for introducing a raw material gas into the reactor, and an exhaust gas of the raw material gas introduced into the reactor outside the reactor. In the vapor phase growth apparatus having an exhaust hole leading out to, the raw material supply ports are provided in the upper portion of the reactor at a predetermined interval corresponding to the number of surfaces of the barrel-type susceptor on which wafers are mounted. An exhaust ring communicating with the exhaust hole is provided in a lower portion of the reactor, and the barrel type susceptor and the exhaust ring are relatively rotated.

The vapor phase growth apparatus according to claim 2 of the present invention is
It is characterized by rotating the exhaust ring.

A vapor phase growth apparatus according to claim 3 of the present invention is
It is characterized in that the wafer mounted on the barrel type susceptor is rotated.

[0011]

According to the vapor phase growth apparatus of the first or second aspect of the present invention, the raw material supply port on the upper part of the reactor has a predetermined number corresponding to the number of surfaces of the susceptor on which wafers are mounted. Since they are provided at intervals, the supply and flow of the raw material gas are made uniform to each surface of the susceptor, and the carrier gas concentration is made uniform. As a result, there is a possibility of realizing a multi-stage growth type susceptor. In addition, an exhaust ring communicating with the exhaust hole is provided in the lower part of the reactor, and the barrel-type susceptor and the exhaust ring rotate relative to each other. Flow uniformly, and the flow of exhaust gas also becomes uniform.

According to the vapor phase growth apparatus of the third aspect of the present invention, since the wafer mounted on the barrel type susceptor is rotated, the film thickness of the epitaxial wafer formed on the wafer can be made uniform.

[0013]

The present invention will be described below in detail with reference to examples. FIG. 1 is a schematic sectional view of a vapor phase growth apparatus showing an embodiment of the present invention, 10 is a barrel type susceptor, 20 is a reactor, and 30 is an exhaust gas exhaust mechanism. Barrel type susceptor 1
0 is supported at the center by a vertically supported support column 11. On the outer periphery of the barrel-type susceptor 10, a plurality of surfaces, for example, six surfaces 13, on which the wafer 12 is placed are provided.
A reactor 20 is arranged so as to surround the barrel-type susceptor 10 with a predetermined gap from each surface 13 of the barrel-type susceptor 10. The barrel type susceptor 10 is heated to a growth temperature by a heating means (not shown).

At the center of the upper portion of the reactor 20, a raw material supply port P0 for introducing hydrogen gas as a carrier gas is provided as shown in FIG. Also, the same as reactor 2
In the present embodiment, six raw material supply ports P1 to P6 for introducing the raw material gas are provided in the upper peripheral portion of 0. The raw material supply ports P1 to P6 are positioned at predetermined positions at positions corresponding to the respective surfaces 13 of the barrel-type susceptor 10 arranged inside the reactor 20.

An exhaust gas exhaust mechanism 30 is provided in the lower part of the reactor 20 for exhausting the exhaust gas of the raw material gas and the carrier gas introduced into the reactor 20 to the outside of the reactor 20. As shown in FIGS. 1 and 3, the exhaust gas exhaust mechanism 30 includes an exhaust ring 31 and an exhaust port 3 connected to the exhaust ring 31.
2 and a galling 33 for rotating the exhaust ring 31. A plurality of fins 38 are provided inside the exhaust ring 31 with a predetermined interval, and a predetermined portion of the outer circumference of the exhaust ring 31 is open.
2 can be opened.

On the outer circumference of the exhaust ring 31, the exhaust ring 3
A galling 33 for rotating 1 is arranged. The gearing 33 is provided with a gear 34 on the lower outer periphery thereof, and the gear 34 meshes with a drive gear 36 of the galling 33 arranged inside a gear box 35 outside the galling 33. The drive gear 36 is connected to a drive source such as a motor (not shown). A flow guide 37 for smoothly guiding the exhaust gas in the reactor 20 to the exhaust ring 31 is provided below the barrel-type susceptor 10.

The introduction of the raw material gas and the carrier gas into the reactor 20 of the vapor phase growth apparatus configured as described above is performed by the pipe as shown in FIG. The pipe PL0 is a vent line, the upstream side of which is connected to a carrier gas cylinder (not shown) via a flow control valve MFC-P0, and a bubble V is used when gas is not supplied to the reactor 20.
The source gas is exhausted from this line by switching between 1 and V4. The pipe MFCD is connected to a raw material supply port P0 provided at the center of the upper portion of the reactor 20 via a flow control valve MFC-V. The upstream side of the pipe PLA is connected to a carrier gas cylinder (not shown), and the downstream thereof is connected to the pipes PLD1 through PLD1 through the flow control valve MFC-A.
The raw material supply ports P1 to P6, which are branched into the PLD6 and are provided in the upper peripheral portion of the upper portion of the reactor 20 shown in FIG. 1, are connected via flow control valves SMFC-D1 to SMFC-D6.

The pipe PLD1 is connected to the raw material supply port P1, the pipe PLD2 is connected to the raw material supply port P2, and so on.
D3 is connected to the raw material supply port P3, ... The pipe PLD6 is connected to the raw material supply port P6. The piping PLB is
The upstream side is connected to a carrier gas cylinder (not shown), and the downstream side is trimethylgallium (TMG).
a) It is connected to the cylinder TM via the flow control valve MFC-B, and its downstream side is connected to the vent line pipe PL0 and the main line pipe PLA. The upstream side of the pipe PLC is connected to the arsine (AsH ₃ ) cylinder AS via the flow control valve MFC-C, and the downstream thereof is connected to the vent line pipe PL0 and the main line pipe PLA.

The piping PLA also includes the pipings PLD1 to PLD.
PLQ via throttle valve SB at the position branched to D6
The downstream side of the reactor 20 is connected to a pressure reducing pump (not shown) provided downstream of the reactor 20.

By providing this throttle valve SB, the following actions occur. Piping PLD with throttle valve SB
1 to PLD6 flow control valves SMFC-D1 to SMFC
-D6 flow rate SMFC-D1 q to SMFC-D6 q can be freely changed. If there is no throttle valve SB, it must be a formula. (In this embodiment, n = 6.)

[0021]

PLAq + PLBq + PLCq = PLD ₁ q + PLD ₂ q + ---- + PLD _n q ... PLAq, PLBq, PLCq are pipes PLA, PLB,
PLC flow rate, PLD ₁ q to PLD 6 q are piping PLD
Each flow rate is from 1 to PLD6. But the formula is practically impossible. The amount of raw material gas such as TMGa is changed for each multilayer film of the epitaxial wafer.
This is because LD1 to PLD6 flow to the side with the least piping resistance. Here, the flow rate P of each pipe PLA, PLB, PLC
The amount of LAq, PLBq, PLCq to be used is determined in advance, so the flow rate can be set accurately, but the piping PLD1 to PLD
Although the flow control valves SMFC-D1 to SMFC-D6 of the LD6 are the same, the flow rate cannot be set accurately because the gas flows at various mixing ratios. Here, PLD ₁ q = PLD ₂
In order to set q = ... = PLD _n q, the total flow rate of PLAq, PLBq, PLCq is set to PLD ₁
Set as shown in the formula so that it becomes larger than the total flow rate of q to PLD6 q.

[0022]

[Equation 2] PLAq + PLBq + PLCq> PLD ₁ q + PLD ₂ q + --- + PLD _n q ...

[0023]

(3) (PLAq + PLBq + PLCq) − (PLD₁q + PLD₂q ＋ ── ＋ PLD _n q) = PLQ ... The difference PLQ is controlled by the throttle valve SB and discharged.
It By doing the above,
Uniform supply to each surface 13 of barrel type susceptor 10 is possible.
Becomes

As described above, it is understood that it is better to have excess PLQ. If PLQ becomes insufficient, an amount determined by the resistance in each pipe will flow into the pipes PLD _{1 to} PLD _n .

A specific example of forming an epitaxial wafer with the vapor phase growth apparatus configured as described above will be described below. In this specific example, the wafer 12 placed on the barrel-type susceptor 10 is adapted to rotate on its own axis, for example, by means shown in FIG. In FIG. 5, 41
Is a rotation tray made of carbon or the like for supporting the wafer 12, and each surface 13 of the barrel type susceptor 10 in the reactor 20.
It is rotatably installed. A tray rotation shaft 42 made of carbon or the like for transmitting a rotational force to the rotation tray 41 penetrates the barrel susceptor 10 rotatably and is led out to a gear chamber 43 on the rear surface side. A tray rotation planetary gear 44 made of quartz glass or the like is attached to the end of the tray rotation shaft 42 led out to the back surface side of the barrel type susceptor 10. A sun gear 45 made of carbon or the like that meshes with the tray rotation planetary gear 44 is coaxially arranged on the outer periphery of the upper shaft of the support shaft 11. A cylindrical sun gear support 46 is coaxially arranged on the outer periphery of the support shaft 11, and by rotating the sun gear support 46, the rotation tray 41 supporting the wafer 12 is rotated.

(Specific example) Number of rotations of exhaust ring: 10 rpm Barrel type susceptor: 3 "x 8 sheets Raw material gas flow rate: 1801000 hydrogen equivalent flow rate Number of raw material supply ports at the top of the reactor: 9 (one is the central hydrogen supply) port) Rotation number of each wafer: 12 rpm

As a result of the above, variations in the film thickness and carrier gas concentration of the epitaxial wafer formed by the barrel type susceptor on each surface of the barrel type susceptor could be controlled within ± 3%.

When the barrel type susceptor is rotated, even if the exhaust ring is not rotated, the gas flow on each surface of the susceptor in the reactor is made uniform as in the case of rotating the exhaust ring without rotating the barrel type susceptor. can do.

[0029]

As described above, according to the vapor phase growth apparatus of the first or second aspect of the present invention, the raw material supply port on the upper portion of the reactor corresponds to the number of surfaces on which the wafer of the susceptor is mounted. Since the plurality of susceptors are provided at a predetermined interval corresponding to the surface of the susceptor, the supply of the source gas and the flow thereof are uniform and the carrier gas concentration is uniform on each surface of the susceptor. The film thickness of the epitaxial wafer can be made uniform. Further, an exhaust ring communicating with the exhaust hole is provided in the lower part of the reactor, and the barrel type susceptor and the exhaust ring are adapted to rotate relative to each other.
The source gas becomes more uniform on each side of the susceptor, and the carrier gas concentration becomes more uniform. As a result, the film thickness of the epitaxial wafer to be formed can be made uniform.

According to the vapor phase growth apparatus of the third aspect of the present invention, the wafer mounted on the barrel type susceptor is rotated, so that the film thickness of the epitaxial wafer formed on the wafer can be made uniform.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional explanatory view showing an embodiment of a vapor phase growth apparatus of the present invention.

FIG. 2 is a plan view showing the arrangement of carrier gas and raw material supply ports of the vapor phase growth apparatus of FIG.

3 is a sectional view showing an exhaust gas exhaust mechanism of the vapor phase growth apparatus of FIG.

4 is an explanatory view showing a pipe for introducing a source gas and a carrier gas into the reactor of the vapor phase growth apparatus of FIG.

5 is a sectional view of a main part showing an example of rotating a wafer mounted on a barrel type susceptor of the vapor phase growth apparatus of FIG.

FIG. 6 is a schematic cross-sectional explanatory view showing an example of a conventional vapor phase growth apparatus.

[Explanation of symbols]

10 Barrel type susceptor 12 Wafer 20 Reactor 30 Exhaust gas exhaust mechanism 31 Exhaust ring 32 Exhaust port 41 Rotating tray MFC-P0 Carrier gas supply port flow control valve SMFC-D1 to SMFC-Dn Raw material supply port flow control valve P0 carrier Gas supply port P1 to Pn Raw material supply port PL0 Carrier gas supply piping PLD1 to PLDn Raw material supply piping

Claims (3)

[Claims] 1. A reactor, a barrel type susceptor for mounting a wafer arranged inside the reactor, a raw material supply port for introducing a raw material gas into the reactor, and a raw material gas introduced into the reactor. In a vapor phase growth apparatus having an exhaust hole for leading out exhaust gas to the outside of the reactor, the raw material supply port has a number corresponding to the number of wafer mounting surfaces of the barrel type susceptor at a predetermined interval corresponding to the surface. An exhaust ring, which is provided in an upper portion of the reactor and communicates with the exhaust hole, is provided in a lower portion of the reactor, and the barrel-type susceptor and the exhaust ring are configured to rotate relative to each other. Vapor growth equipment. 2. The vapor phase growth apparatus according to claim 1, wherein the exhaust ring is rotated. 3. The vapor phase growth apparatus according to claim 1, wherein the wafer mounted on the barrel type susceptor is rotated.