JP2525009B2 - Vapor phase growth equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vapor phase growth apparatus for performing vapor phase growth of a semiconductor thin film on a wafer surface on a susceptor.

[Prior Art] A conventional vapor phase growth apparatus of this metalorganic chemical vapor deposition method (hereinafter referred to as MOCVD method) has a susceptor 2 supported by a shaft 1 placed in a container 3 as shown in FIG. In addition, an inner tube 4 surrounding the susceptor 2 is placed in the container 3 at a position corresponding to the position where the susceptor 2 is placed, and gas for vapor phase growth is supplied from the inlet 5 into the container 3 to flow in one direction. Thus, the semiconductor thin film is crystal-grown on the surface of the wafer 6 on the susceptor 2, and the exhaust gas is discharged from the outlet 7 near the other end of the container 3. Reference numeral 8 is a lid that closes the opening 3E of the container 3 for inserting and removing the susceptor 2 and the inner tube 4.

In this case, the inner pipe 4 is provided to prevent the reaction product from adhering to and depositing on the inner wall of the container 3 and to facilitate the removal of the reaction product outside the container 3.

However, in such a structure, the inner tube 4 and the container 3 are
Since there is a gap 9 between the gap 9 and the gap 9, and the gap 9 is open to the upstream side, the gas for vapor phase growth enters the gap 9 and the reaction product adheres to and deposits on the inner wall of the container 3. There was a point.

In order to solve this, as shown in FIG.
3A on the portion of the container 3 adjacent to the upstream end of the
Is provided so that the upstream side of the stepped portion 3A is the small diameter portion 3B and the downstream side of the stepped portion 3A is the large diameter portion 3C.
There is also proposed a vapor phase growth apparatus having a structure in which one end of the auxiliary pipe 10 is provided in the stepped portion 3A, and the inside of the auxiliary pipe 10 is substantially matched with the inner diameter of the small diameter portion 3B of the container 3. In such a vapor phase growth apparatus, an auxiliary tube whose one end is located at the step 3A
The presence of 10 can prevent the reaction product from adhering to and depositing on the inner wall of the container 3.

[Problems to be Solved by the Invention] However, in such a vapor phase growth apparatus, the container 3
Since the inner tube 4 and the auxiliary tube 10 must be housed inside, the structure is complicated and it takes time to replace the inner tube 4. Further, in such a structure, the container 3
Since the inner tube 4 projects inside, the gas flow flowing in the container 3 is disturbed, and there is a problem that it is difficult to uniformly grow the film thickness on the wafer 6.

It is an object of the present invention to provide a vapor phase growth apparatus that can prevent turbulence of a gas flow even if an inner tube is housed in a container and has a simple structure.

[Means for Solving the Problems] To explain the configuration of the present invention for achieving the above object, the present invention places a susceptor supported by a shaft in a container, and the susceptor is provided in the container. An inner tube surrounding the susceptor is placed corresponding to a position to be placed, and a gas for vapor phase growth is caused to flow in one direction in the container to cause crystal growth on a surface of a wafer on the susceptor, The container is formed with a small-diameter portion on the upstream side and a large-diameter portion on the downstream side with the step portion in the middle as a boundary, and the small-diameter portion is provided with an extension portion projecting from the step portion into the large-diameter portion, The inner pipe is arranged in the large-diameter portion with one end fitted to the outer periphery of the extension portion.

[Operation] As described above, when one end of the inner pipe is fitted to the extension portion of the small diameter portion protruding into the large diameter portion and the inner pipe is arranged in the large diameter portion, the inner pipe does not protrude into the container and the gas flow is prevented. The surface defects of the wafer can be reduced. Further, it is not necessary to further set an auxiliary pipe in the container, which simplifies the structure. Furthermore, the presence of the extension facilitates positioning of the inner tube.

Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings. 1 to 5 show an example in which the present invention is applied to a vapor phase growth apparatus by a lateral type chemical transport method (hereinafter, CVT method). The parts corresponding to those in FIGS. 8 and 9 described above are designated by the same reference numerals. Also in this embodiment, the container 3 having a circular cross section has a stepped portion in the middle thereof.
The small diameter portion 3B is formed on the upstream side of 3A and the large diameter portion 3C is formed on the downstream side, and the small diameter portion 3B has a larger diameter portion 3C than the step portion 3A.
An extension portion 3D protruding inward is provided with the same inner diameter as the small diameter portion 3B. In this case, the inner diameter of the small diameter portion 3B and the extension portion 3D is, for example, 40 mmφ, the inner diameter of the large diameter portion 3C is, for example, 54 mmφ, and the length of the extension portion 3D is about 20 mm.

The inner pipe 4 in this embodiment has a cylindrical portion 4A having an inner diameter substantially equal to the outer diameter of the extension 3D of the container 3, and a tapered portion 4B gradually changing from a circular cross section of the cylindrical portion 4A to a square cross section.
The tapered portion 4B is composed of a square tubular portion 4C having a quadrangular cross section that is continuous with an end portion of the quadrangular cross section. Inner tube 4 like this
Is a large diameter part of the container 3 with the cylindrical part 4A inserted into the outer periphery of the extension part 3D.
It is located in 3C. In this case, the inner diameter of the cylindrical portion 4A is, for example, 47 mmφ which is 1 mm larger than the outer diameter of the extension portion 3D, and the square tubular portion 4C.
The hole has a width of 47 mm and a height of 30 mm, for example.

Further, the boat 11 is arranged in the small diameter portion 3B of the container 3,
A solid gallium Ga source 12 is placed on the boat 11.

Next, an example of crystal-growing GaAs on the wafer 6 with such an apparatus will be described. First, the inner tube 4 is inserted into the container 3 and vapor phase etching is performed. After completion of this vapor phase etching, the inner tube 4 is replaced with a new one, the Ga source 12 is inserted into the container 3 at a predetermined position by the boat 11, and the Ga source 12 is heated to about 850 ° C. by a heater (not shown) outside the container 3. Heat up to. At this time, AsCl ₃ and carrier gas (H ₂ ) are supplied into the container 3 from the inlet 5 to dissolve As in the Ga melt. The chloride of Ga and small amounts of As, GaAs, etc. generated at this time are in the inner tube 4
And the inner tube 4 is replaced after this step is completed. Next, insert the GaAs wafer 6 into the container 3 via the susceptor 2,
The wafer 6 and the Ga source 12 are heated to a predetermined temperature (wafer: 7
The temperature is raised to 00-750 ° C, Ga source 850 ° C), AsCl ₃ and carrier gas (H ₂ ) are supplied into the inner tube 4 from the inlet 5, and GaAs is supplied.
Epitaxial growth is performed on the wafer 6. At this time, the generated Ga chloride, As, and GaAs are deposited on the inner tube 4. The inner tube 4 is replaced, the heater is turned off, and the wafer 6 is cooled.

According to the manufacturing method using the apparatus of the present invention as compared with the conventional apparatus, the number of defects on the wafer surface was reduced by 10 to 20%, and the uniformity of the crystal film thickness and its reproducibility were improved.

Typical growth conditions Carrier gas flow rate H ₂ : 1000cc / min AsCl ₃ bubbling flow rate H ₂ : 300cc / min Ga source temperature: 850 ℃ Wafer temperature: 730 ℃ Wafer size: 30mm × 20mm Number of wafers: 2 The device shown in Figs.
Of course, instead of supplying the Ga source 12, the MOCVD method of supplying the source gas from the inlet 5 can also be applied.

FIGS. 6 and 7 show an example in which the present invention is applied to a vapor phase growth apparatus by a vertical type MOCVD method. In this embodiment, the container 3 is composed of a reactor 13 and a pre-chamber 14 arranged one above the other. At the location of the reactor 13, the container 3 is formed with a small diameter portion 3B on the upstream side and a large diameter portion 3C on the downstream side centering on the stepped portion 3A, and the small diameter portion 3B has a larger diameter portion 3C than the stepped portion 3A as described above. Extension that projects inward
3D is provided with an inner diameter equal to that of the small diameter portion 3B. For example, the inner diameter of the small diameter part 3B and the extension part 3D is 140mmφ, the large diameter part 3C
The inner diameter of is 156 mmφ. One end is fitted to the extension portion 3D and the inner pipe 4 is arranged in the large diameter portion 3C. Inner tube 4 is an extension
The inner diameter of the portion to be fitted to the 3D is approximately equal to the outer diameter of the extension portion 3D, and is formed to be 146 mmφ, for example, and the other portion is extended 3
It is formed to have a diameter almost equal to that of D. The inner pipe 4 is mounted on an inner pipe lift base 15, and the inner pipe lift base 15 is moved up and down by an inner pipe lift shaft 16. An exhaust port 17 is formed in the inner pipe 4 corresponding to the outlet 7 of the container 3. A cooling jacket 18 is liquid-tightly attached to the outer periphery of the large diameter portion 3C of the container 3 continuous with the step portion 3A, and a heating means 19 such as an induction heating coil for heating is disposed on the outer periphery thereof. A gate valve 20 is provided in the container 3 under the inner pipe 4 so that upper and lower partitions in the container 3 can be closed. Container 3
An opening / closing door 21 is provided in the pre-chamber 14 part. At the lower end of the purine chamber 14, there is a seal part 2 for each shaft 1, 16.
2,23 are provided.

In such a device, first, the gate valve 20 is occupied, the door 21 of the pre-chamber 14 is opened, and the inner pipe 4 is moved up and down.
Installed on top of the above, closed the door 21, and purged the pre-chamber 14 with a replacement gas such as H ₂ . After purging, the gate valve 20 is opened, the susceptor 2 is first raised to a predetermined position, and then the inner pipe 4 is raised to a predetermined position together with the inner pipe lifting table 15. When the inner pipe 4 is raised, the step portion 4A of the inner pipe 4 extends
It comes into contact with the 3D end, and no gap is created. In order to make the film thickness uniform, the carrier gas (H ₂ ) is supplied from the inlet 5 into the reactor 13 while rotating the susceptor 2 via the shaft 1, and the wafer 6 on the susceptor 2 is heated by the heating means 20.
When the temperature reaches 300 ° C, the inlet 5
Arsine (AsH ₃ ) which is a gas for vapor phase growth is flowed from
After the temperature of the wafer 6 stabilizes at 700 ° C., trimethylgallium (TMG) is flown from the inlet 5 to remove the GaAs crystal from the wafer 6.
Grow on. During the growth operation, GaAs and As are considerably attached to the surface of the inner tube 4, but are hardly attached to the reactor 13. When the growth is completed, the heating is stopped and the temperature of the wafer 6 is 400 ° C.
When that happens, the supply of AsH ₃ is stopped. When the temperature of the wafer 6 has dropped to 100 to 200 ° C., the supply of the purge gas is stopped, the gate valve 20 is opened, the inner pipe 4 is lowered together with the inner pipe lifting table 15, and then the susceptor 2 is lowered. When the lowering is complete, close the gate valve 20 and pre-chamber 14 with N ₂ gas.
Purge the inside. After purging, the pre-chamber 14 door 21
Open, take out the inner tube 4, then take out the wafer 6,
A new wafer 6 is set on the susceptor 2, then a new inner tube 4 is set on the inner tube lift 15 to start the next growth operation.

Typical growth conditions Carrier gas flow rate H ₂ : 100 / min Group V source gas flow rate AsH ₃ : 160cc / min Group III bubbling gas H ₂ : 100cc / min Wafer temperature: 700 ℃ Susceptor shape: Hexagonal pyramid Number of wafers: 6 The number of surface defects of the wafer 6 thus grown was 500 / cm ² in the conventional case, but 100 to 20 in the present invention.
The number decreased to 0 / cm ² . In addition, the reaction product adhered to the container 3 almost disappeared, and the reaction product adhered to the reactor 13 almost disappeared, so that the replacement frequency of the liquor 13 could be drastically reduced.

[Effects of the Invention] As described above, according to the present invention, a step portion is provided in the middle of a container, and a small diameter portion is provided on the upstream side and a large diameter portion is provided on the downstream side with the step portion as a boundary, and a step is provided on the small diameter portion. Since an extension part is provided that protrudes into the larger diameter part than the other part and one end is fitted to the outer circumference of this extension part and the inner pipe is provided inside the large diameter part, the inner pipe does not protrude into the container and disturbs the gas flow. The surface defects of the wafer can be reduced. Further, according to the present invention, the deposition and deposition of the reaction product on the container can be significantly reduced, and the frequency of container replacement can be significantly reduced.
Further, in the present invention, since it is not necessary to insert auxiliary pipes other than the inner pipe, there is an advantage that the structure is simple and handling at the time of replacement is easy. Further, in the present invention, since the extension portion is fitted to the inner tube, there is an advantage that the positioning of the inner tube is facilitated and the shift during use can be prevented.

[Brief description of drawings]

1 is a vertical sectional view showing a schematic configuration of a first embodiment of an apparatus according to the present invention, FIG. 2 is an enlarged vertical sectional view of an essential part of FIG. 1, and FIG.
FIG. 4 is a longitudinal sectional view of the inner pipe used in the first embodiment, FIG. 4 is a sectional view taken along line XX of FIG. 3, and FIG. 5 is a sectional view taken along line YY of FIG. FIG. 8 is a vertical cross-sectional view of a second embodiment of the device according to the present invention, FIG. 7 is an enlarged vertical cross-sectional view of an essential part of FIG. 6, and FIGS. 8 and 9 show two examples of conventional devices. FIG. 1 ... Shaft, 2 ... Susceptor, 3 ... Container, 3A ...
Step portion, 3B ... small diameter portion, 33C ... large diameter portion, 3D ... extension portion, 4 ... inner tube, 5 ... inlet, 6 ... wafer, 7 ... exit.

Claims (1)

(57) [Claims] 1. A susceptor supported by a shaft is placed in a container, and an inner tube surrounding the susceptor is placed in the container at a position where the susceptor is placed, and vapor phase growth is carried out in the container. In a vapor phase growth apparatus for flowing a working gas in one direction to grow crystals on the surface of a wafer on the susceptor, the container has a small diameter portion on the upstream side and a large diameter portion on the downstream side with a step portion in the middle as a boundary. An extension portion is formed in the small diameter portion and protrudes into the large diameter portion from the step portion, and the inner pipe is disposed in the large diameter portion by fitting one end to an outer periphery of the extension portion. A vapor phase growth apparatus characterized in that