JPH10158100A - Vapor growth device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems such that in a conventional vertical vapor growth device, since the supply port of gaseous reactants has a nozzle-like shape, the decomposition reaction of the gaseous reactants is not stabilized near the nozzle and also, since positions of the supply port and the discharge port of the gaseous reactants are asymmetric, variation in film thickness or properties of a deposited film on a substrate placed on a susceptor is caused. SOLUTION: In this device, a gas passage forming body 20 is placed in the space between a gaseous raw material introducing port 7 and a susceptor 4 and a gaseous raw material is introduced through the gas introducing port 7 toward the central part of the gas passage forming body 20 and first, radially diffused on the body 20 and thereafter, allowed to flow on the surface of susceptor 4, on which substrates 3 are placed, toward the central part of the susceptor 4, to uniformize the gas flow. As a result, the variation in film thickness or properties of a deposited film on each of the substrates 3 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a vapor phase growth apparatus for performing metal organic chemical vapor deposition (MOCVD), which is a kind of vapor phase growth method.

[0002]

2. Description of the Related Art In general, the MOCVD method uses a low-cost substrate because crystals can be grown on a heterogeneous substrate.
A large amount of crystals can be supplied at low cost. FIG. 4 shows a cross-sectional structure of a conventional vertical vapor phase growth apparatus. In the figure, reference numeral 1 denotes a reaction vessel, 2 denotes a reaction gas outlet, and 4 denotes a semiconductor substrate provided in the reaction vessel. 5 is a heating device for heating the susceptor 4, 7 is a raw material gas inlet, 6 is a drive shaft for supporting and rotating the susceptor 4, and includes a drive motor 9 and a gear mechanism 8. Rotate. Reference numeral 10 denotes a material gas exhaust port.

Next, the operation will be described. The susceptor 4 provided in the reaction vessel 1 is heated to a predetermined temperature (500 to 800 ° C.) by a heating device 5 provided in the reaction vessel.
Heated. At this time, the gas sent from the raw material gas inlet reaches the substrate 3 placed on the susceptor 4 from the gas outlet 2 and grows a semiconductor crystal film on the surface of the substrate 3 by thermal decomposition. Further, the source gas is exhausted from the exhaust port 10 through the gap 11 between the reaction vessel 1 and the susceptor 4. Here, during the film growth, the susceptor 4 is rotated by the rotation of the drive shaft 6 to achieve uniform crystal growth in the rotation direction.

[0004]

The conventional vertical vapor phase epitaxy apparatus is constructed as described above,
Is located at the center of the susceptor, the gas flow is uniform near the outlet, but it is difficult to obtain a uniform flow at the outer periphery of the susceptor, and the position of the gas exhaust port 10 is Due to the asymmetry, when the diameter of the susceptor is large, or when a thin deposited film is required, the thickness of the deposited film may vary due to uneven gas flow. Furthermore, since the introduction gas outlet 2 has a nozzle shape, there is a problem that the decomposition reaction of the raw material is not stable in the vicinity of the outlet, and the carrier concentration in the deposited film varies. The present invention makes the flow of the source gas in the reaction vessel symmetric and uniform during the growth of the semiconductor deposited film, stabilizes the decomposition of the source gas on the susceptor, and increases the thickness of the semiconductor film in a wide area of the susceptor. And to reduce the variation in carrier concentration.

[0005]

According to a first aspect of the present invention, there is provided a vapor phase growth apparatus according to the present invention, wherein a reaction gas is supplied from a substantially central portion of a substrate mounting surface of a susceptor. A flow path forming body is provided above the susceptor substrate mounting surface, whereby the raw material gas is once spread in the outer peripheral direction of the susceptor, then is uniformly flowed on the substrate surface, and exhausted from almost the center of the reaction vessel. And

According to a second aspect of the present invention, in the vapor phase growth apparatus according to the first aspect of the present invention, the pressure between the space formed between the surface of the susceptor and the flow path forming body and the space formed between the back surface of the susceptor and the reaction vessel. A gas supply port for adjusting the balance of the pressure is provided in the reaction vessel.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 1 shows an example of a method according to the present embodiment. In the following drawings, the same components as those in FIG. 4 according to the conventional method are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 1 will be described taking as an example a case where a GaAs film is epitaxially grown on a GaAs substrate by MOCVD. In FIG. 1, trimethylgallium (TMG) and arsine (AsH ₃ ) were supplied from a gas supply device (not shown) via a gas inlet 7 provided at the upper center of the reaction vessel 1 using hydrogen gas as a carrier.
The susceptor 4 on which the plurality of substrates 3 are placed is heated to 600 ° C. by the RF heating device 5 and controlled by a thermocouple (not shown). Reference numeral 20 denotes a flow path forming body which is a feature of the present invention, and is fixed to the reaction vessel 1 by a flow path forming body receiver 21 having a support arm shape or having a large number of through holes. A hole for intake is provided at the center of the susceptor 4, and is connected to an exhaust port 10 provided at the center of the susceptor drive shaft 6. The susceptor 4 is configured to be rotatable by the drive motor 9 via the drive shaft 6. Reaction vessel 1
And the clearance L1 between the flow path forming body 20 and ₅ to 30 mm
Value.

The gas introduced through the gas inlet 7 is
The central exhaust port 1 of the susceptor 4 extends from the outer peripheral side of the susceptor 4 in the gas flow path which is uniformly spread in the radial direction by the flow path forming body 20 and is surrounded by the back surface of the flow path forming body 20 and the surface of the susceptor 4.
Flow towards zero. As shown in FIG. 1, the flow path forming body 20 has a smooth upper surface and a concave rear center so that the raw material gas flows uniformly on the substrate mounting surface of the susceptor 4. That is, the cross-sectional shape is such that the outer peripheral portion is thicker and thinner toward the center.

In FIG. 1, since a gap 25 exists between the reaction vessel 1 and the susceptor 4, the raw material gas flows into the dead space 26 on the back side of the susceptor 4 through the gap 25, and the gas on the susceptor surface is removed. This may disrupt flow uniformity. In order to prevent this, a shield plate 22 is provided on the inner periphery of the reaction vessel 1, and a purge gas is supplied from a gas inlet 23 provided in the base 1 a of the reaction vessel 1 to the dead space 2.
And a purge gas discharge hole 24 provided in the drive shaft 6.
More exhaust. By adjusting the pressure of the purge gas, the source gas does not flow into the dead space 27 and the flow of the source gas on the surface of the susceptor 4 can be kept uniform.

Further, as a condition for keeping the flow of the reaction gas on the surface of the susceptor 4 uniform, it is important that the center axis of the reaction vessel 1 and the center axis of the flow path forming body 20 coincide as much as possible. This is achieved by adjusting the position of the channel forming member receiver 21. It is desirable that the deviation (coaxiality) between the central axes of the reaction vessel 1 and the flow path forming body 20 be 0.5 mm or less when the diameter of the reaction vessel is 200 mm or less, and 1.0 mm or less when the diameter of the reaction vessel is 200 mm or more. The distance L ₂ between the rear surface and the susceptor 4 of the passage forming body 20 20~60m
m, and the value of L ₂ is susceptor 4 as described above.
From the outer periphery toward the center.

As a result of the epitaxial growth of the GaAs film by the above-described apparatus, the flow of the source gas on the susceptor surface can be made extremely uniform. What was 0.5% was ±
It was within 1.0%. In addition, the variation in the thickness of the eight substrates on the same susceptor was also reduced from ± 2.1% to ± 2.1%.
It was improved to 1.6%.

FIG. 2 shows a modification of the first embodiment. In FIG. 1, the upper surface of the reaction vessel 1 is substantially parallel to the reaction vessel pedestal 1a, but in FIG. 2, the cross-sectional shape of the reaction vessel 1 is hemispherical, semi-elliptical, or a combination of both. The flow path forming body 20 has a similar shape. The example of FIG. 2 is advantageous in that the reaction gas can be easily and uniformly flowed particularly when the reaction vessel is large.

(Embodiment 2) FIG. 3 shows a second embodiment according to the present invention. In the first embodiment, the substrate is mounted on the upper surface of the susceptor 4, but in the present embodiment, the substrate is of a so-called face-down type mounted on the lower surface of the susceptor 4. For this reason, the substrate 3 is fixed to the susceptor by a plurality of claws (not shown) provided on the susceptor 4. The face-down method has an advantage that dust and the like do not adhere to the substrate. In this embodiment of the face-down system, the flow path forming body 20 is also provided in the direction opposite to that of the first embodiment, and the susceptor 4 and the flow path forming body 20 can be rotated independently. That is, the rotation of the susceptor drive shaft 6 is controlled by the drive motor 9 ′, and the flow path forming member drive shaft 27 is controlled by the drive motor 9.

The raw material gas is supplied from an inlet provided in the lower cylindrical portion 1b of the reaction vessel along the rotation axis 27 of the flow path forming body 20, and after the flow is once diffused in the radial direction by the flow path forming body 20, Then, the gas flows through the flow path between the flow path forming body 20 and the susceptor 4 and is exhausted by the exhaust port 10 provided at the center of the flow path forming body 20. Since the space between the reaction vessel 1 and the susceptor 4 has a dead space, a purge gas can be supplied and exhausted by the gas inlet 23 and the discharge hole 24 provided in the reaction vessel 1. Further, a shielding plate 22 is provided inside the reaction vessel 1 in order to prevent the raw material gas from flowing into the dead space.

The susceptor 4 can be heated by either a resistance heating method or an infrared lamp heating method. In the case of this embodiment, since the rotation of the susceptor 4 and the flow path forming body 20 is controlled independently, even if the susceptor 4 is enlarged,
It is easy to make the flow of the source gas on the surface of the substrate uniform, and it is possible to perform deposition processing on a large number of substrates.

Using the method according to the present embodiment, a film having the same structure as that described in Embodiment 2 was deposited, and the film thickness and the carrier concentration were compared with the conventional method.
± 1.5% to ± 1.2% for in-plane thickness uniformity
The variation in the film thickness between the surfaces of the 16 substrates mounted on the same susceptor is from ± 2.1% to ± 1.6%, and the variation in the carrier concentration of the 16 substrates is ±
Each of them was improved from 2.3% to ± 1.5%.

[0018]

As described above in detail, according to the present invention, the material gas is supplied from substantially the center of the susceptor and exhausted from substantially the center of the susceptor. After the source gas is once expanded in the diameter direction of the susceptor, the source gas on the surface of the substrate mounted on the susceptor is made to flow uniformly, and as a result, the uniformity of the deposited film thickness in the plane of the substrate and the The variation in the film thickness was remarkably improved. In addition to the susceptor heating device,
By adding a heating or cooling device to the flow path forming body itself and controlling the temperature distribution on the substrate mounting surface of the susceptor in the radial direction of the susceptor, the uniformity of the carrier concentration can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a modification of the first embodiment of the present invention.

FIG. 3 is a configuration diagram showing a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a vapor phase growth apparatus according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction container 2 Gas outlet 3 Substrate 4 Susceptor 5 Heating device 6 Drive shaft 7 Gas inlet 8 Gear 9 Drive motor 10 Exhaust port 20 Flow path forming body 21 Flow path forming body receiver 22 Shielding plate 23 Purging gas introduction Port 24 purge gas discharge port 27 channel forming body drive shaft

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/205 H01L 21/205

Claims (2)

[Claims] 1. A reaction container, a susceptor for holding a substrate provided in the reaction container, a gas inlet for supplying a source gas into the reaction container, and exhausting unnecessary gas in the reaction container. In a vertical (pancake-type) reaction furnace having an exhaust port that vents, a gas flow path forming body is provided between the gas introduction port and the susceptor, and the gas flow path is directed from the gas introduction port to the center of the flow path forming body. A gas phase growth apparatus characterized in that a source gas to be introduced is once diffused radially by a flow path forming body and then guided toward the center of the susceptor on the substrate mounting surface of the susceptor. 2. The vapor phase epitaxy apparatus according to claim 1, wherein a pressure between a space formed between the susceptor surface and the flow path forming body and a space between the susceptor back surface and the reaction vessel are adjusted. A gas phase growth apparatus wherein a gas supply port to be adjusted is provided in a reaction vessel.