JPS6072223A - Device for growing semiconductor thin film - Google Patents

Abstract

PURPOSE:To eliminate the noxious thermal decomposition in a thin film growing device for growing compound semiconductor thin films till a material gas reaches a substrate by providing a substrate-carrying pedestal surrounded by a sheath of a small diameter in a vertical tube reactor and a flow restrain spacer provided with a neck put in its upper part and a funnel part in its lower part above said pedestal so as to blow the material gas onto the substrate on the pedestal through said spacer. CONSTITUTION:A pedestal 10 for carrying a compound semiconductor substrate 8 is arranged in a tube reactor 2 surrounded by a water-cooled outer tube 3 with being supported by a supporting member 9 and these are surrounded by a sheath 31 of a small diameter. Next, a flow path restrain spacer 21 provided with a funnel part 24 in its lower part, a neck part 22 in its upper part and further an expanded part 23 in the middle of them is arranged above the pedestal 10 thereby blowing a material gas 37 from an upper gas introducing tube 6 onto the pedestal 10 through the spacer 21. Thus, thermal decomposition of the gas 37 till it reaches the substrate 8 can be avoided effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a semiconductor thin film growth apparatus suitable for growing semiconductor thin films, particularly compound semiconductor thin films.

(Description of Prior Art) As a method for epitaxially growing compound semiconductor thin films such as GaAs and AlAs, an organometallic compound thermal decomposition method, which is different from the conventional liquid phase epitaxial growth method, has been proposed. This method is called the MO-CVD method, and is a method of crystal-growing a compound semiconductor thin film by thermally decomposing an organic metal. The basic characteristics of this MO-CVD method include that the composition and growth rate of the grown film can be controlled by the raw material transport law, and that it is an irreversible reaction and does not have the adverse effects of substrate etching. Therefore, it has recently attracted much attention as a core technology for optical semiconductor devices and ultra-high frequency/ultra-high speed devices.

However, many phenomena are unclear because the theories of thermal decomposition and growth reactions of organic metals are still underdeveloped. In particular, the quality of the grown epitaxial layer tends to be greatly influenced by the structure of the reaction tower, the method of supplying various gases, etc., which has been a major problem.

FIG. 1 is a cross-sectional view schematically showing a typical structure of a conventional reaction tower used in the No-11uVD method.

In this structure, the reaction tower 1 has a double structure made of quartz glass, with an outer tube 3 provided around the outer periphery of an inner reaction tube 2, and inlet/outlet ports 4.5 provided above and below the outer tube 3. The structure includes a cooling device that cools the outer wall of the reaction tube 2 by flowing cooling water through the tube.

A gas inlet 6 is provided at the upper part of the reaction tube 2, and a gas discharge lower is provided at the lower part.
a(CH3) 3, Al(CH3) 3, etc.) and hydride gas (e.g., ASH3, PH3, etc.) are supplied into the reaction tube together with a carrier gas (e.g., H2, Ar, etc.), and the reaction is started. The remaining unnecessary gas is discharged from the gas outlet pipe 7.

Further, a compound semiconductor substrate 8 on which an epitaxial growth layer is to be grown is mounted on the upper surface 10a of a carbon pedestal 10 installed in the reaction tube 2 by a support 9, and this is a heating device provided on the outer periphery of the outer tube 3. High frequency induction wire ring 1
1, it has a structure that heats to 800 to 800°C. In order to uniformly supply gas to the substrate 8, a mesh member 12 made of quartz glass is provided below the gas inlet 6, thereby mixing and dispersing the mixed gas flow from the gas inlet 6. .

(Disadvantages of the prior art) In order to obtain a homogeneous growth layer using the MO-CVD method, it is necessary to carry out the thermal decomposition reaction at an appropriately low temperature so that no harmful reactions occur. In the conventional reaction tower structure described above, due to the temperature rise of the pedestal during epitaxial growth, the temperature of the compound semiconductor substrate and the pedestal 4 =
The temperature of the gas near J increases, and as a result, a strong convection 13 of the mixed gas flow occurs, which greatly stirs the mixed gas 4 that has passed through the gas inlet 6 or the mesh member 12 for mixing and dispersion. , the temperature of the mixed gas in the reaction tube 2 will rise excessively. Therefore, before the mixed gas involved in epitaxial growth reaches the vicinity of the compound semiconductor 8, each component gas undergoes a thermal decomposition reaction. This thermal decomposition reaction has a significant effect on the ratio of each component element of the mixed gas that reaches the surface of the compound semiconductor substrate 8. Therefore, the convection of such a mixed gas flow can reduce in-plane non-uniformity on the substrate surface. This is an extremely large obstacle to achieving a high-quality epitaxial growth layer.

(Object of the invention) The object of the present invention is to fundamentally solve the conventional drawbacks,
The raw material mixed gas is supplied to the compound semiconductor substrate while being maintained at a low temperature, and the high temperature spent gas or other unnecessary gas after the reaction is reliably separated from the raw material mixed gas and exhausted. An object of the present invention is to provide a semiconductor thin film growth apparatus having a structure that prevents harmful fine powder generated by a mixed gas from falling onto the surface of a compound semiconductor.

(Structure of the Invention) In order to achieve this object, according to the present invention, a gas flow regulating device is provided in the reaction tube to fundamentally improve the relative relationship between the mixed gas in the reaction tube and the compound semiconductor substrate. In particular, therefore, the semiconductor thin film growth apparatus of the present invention includes a gas flow path regulating device disposed within the reaction tube,
This gas flow path regulating device consists of a large part for forming a space for mixing the raw material gas supplied from the gas inlet, and a compound semiconductor substrate mounted on the surface of the pedestal that is provided continuously with this large part. A low I/Row I/O system that radiates feedstock gas toward the target and separates the temperature-rising gas from the feedstock gas.
and a flow path regulating spacer disposed between the gas inlet and the surface of the pedestal, and further, the gas flow regulating device has an outer wall of the flow channel regulating spacer and a surface of the reaction tube. It is characterized by having a partition between the inner wall and the inner wall that vertically divides the space inside the reaction tube, and further comprising a lower exhaust gas port on the gas discharge port side of the reaction tube.

Furthermore, in carrying out the present invention, the gas flow path regulating device includes:
It is preferable to provide a shielding spacer in the gap between the flow path regulating spacer and the pedestal.

Furthermore, in carrying out the present invention, the gas flow regulating device is provided with a sheath pipe that covers the pedestal except for the compound semiconductor substrate portion on the surface of the pedestal and communicates with the gas exhaust port. is suitable.

(Description of Examples) Examples of the present invention will be described below with reference to FIG. In these figures, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and detailed explanation thereof will be omitted. Further, these figures are only shown schematically with some parts omitted to the extent that the structure of the present invention can be understood.

FIG. 2 is a schematic cross-sectional view showing one embodiment of the reaction tower of the semiconductor thin film growth apparatus of the present invention.

According to the present invention, as is clear from FIG. 2, a gas flow path regulating device is provided within the reaction tube 2 of the reaction tower 20. Various gases involved in epitaxial growth include Ga(CH3
) 3, A sentence (CH3) 3 etc. organometallic compound gas,
These raw material gases include hydride gases such as AsH3 and PH3, impurity addition gases, and carrier gases such as H2 and Ar. These raw material gases are mixed in several sub-groups and then heated to the center of the upper part of the reaction column. The gas is supplied into the reaction tube 2 from the inflow d6.

The above-mentioned gas flow regulating device has a flow regulating spacer 21 made of, for example, quartz glass to regulate the flow of these raw material gases and prevent the temperature of the inflowing gas from rising. This spacer 21 is detachably inserted between the waste inlet 6 and the pedestal 10.

Ko (7) ;2. In the illustrated example, the sacer 21 includes a neck 22 arranged to communicate with the gas inlet 6, an enlarged portion 23 continuous to the neck 22, and a funnel portion 24 continuous to the enlarged portion 23. It consists of 25 is an opening of the funnel portion 24. This huge 8B23 is gas mixing space 2
6, and its central portion is, for example, a cylindrical portion. The funnel part 24 has a tapered bottom structure that is inclined downward from this cylindrical part toward the center of the upper surface 10a of the pedestal 10, and the end part forming 025 is connected to the substrate 8. The mixed raw material gas mixed in the gas mixing space 2B is uniformly and widely spaced from the opening 25 toward the compound semiconductor substrate 8 mounted at the center of the surface of the pedestal 10 at an appropriate distance from the surface. Configure so that radiation can be supplied. Furthermore, this funnel portion 24 is
The gas flow which has become an upward flow due to the temperature rise on the upper surface 10a of the pedestal 10 is prevented from flowing into the opening 25 of the spacer 21, and is completely separated from the mixed gas supplied from the opening 25. This spacer 21
is fixed to the reaction tube 2 and has a partition wall 28 for preventing the gas flow near the inner wall of the reaction tube 2 from flowing into the upper gas regulation area 27.

In the illustrated example, the partition wall is installed at the boundary between the enlarged portion 23 and the funnel portion 24, but the installation location is not limited thereto. This partition wall 28 is connected to the reaction tube 2.
It is detachably supported and fixed by a flange-like projection 28 provided on the inside of the holder. This partition wall 28 divides the space inside the reaction tube 2 into upper and lower parts. Exclusively published from 30 onwards.

Furthermore, the gas flow regulating device includes a separate source tube 31 made of quartz glass, for example.
can be included. As shown, this sheath tube 31 is for preventing the mixed gas flow from flowing into the lower gas regulation area 32 . This sheath tube 31 has, for example, an opening 31a that surrounds the semiconductor substrate 8 mounted on the surface 10a of the pedestal 1o at an appropriate interval, and a support provided at the bottom of the reaction tube 2. It is detachably attached and fixed to the body 33. With this sheath tube 31,
It is possible to prevent gas heated in contact with a surface other than the upper surface 10a of the pedestal IO from mixing with the mixed gas flow. Then, the gas in the gas regulation area 32 surrounded by this sheath pipe 31 is made to come out by υ1 from the Kasugi 1-exit lower. Then, the mixed residue flowing down between the reaction tube 2 and the sheath tube 31 is discharged from the lower exhaust gas port 34 provided at the lower end of the reaction tube 2. Further, the waste flow path regulating device can include a shielding spacer 35 provided in the gap between the funnel portion 24 of the flow path regulating spacer 21 and the pedestal surface 10a. This shielding spacer 35 acts to prevent the radiant heat from the surface 10a of the pedestal 10 from heating the flow path regulating spacer 21, and also effectively controls the gas flow that has become an upward flow due to the temperature increase near the compound semiconductor substrate 8. It serves to guide the reaction tube 2 toward the inner wall of the reaction tube 2. Accordingly, this shielding spacer 35 may be any structure that performs the functions described above. In the illustrated example,
For example, it is made of quartz glass and has a central opening 35a that allows the mixed waste flow supplied from the opening 25 of the flow path regulating spacer 21 to pass through to the semiconductor substrate 8, and a central opening 35a that regulates this opening 35a and that extends upward toward the tube wall of the reaction tube 2. and a funnel-shaped inclined part 35b which is inclined at .

The inclined portion 35b has a bent portion 35d which is inclined toward the inner wall from the end thereof and has an opening 35c through which the waste flow passes. The bent portion 35d is then removably fixed to a collar-shaped projection 36 provided on the inner wall of the reaction tube 2.

The device of the present invention also has a double pipe structure like the conventional device, and is cooled by water or other cooling medium.
It is designed to be able to cool the reaction tower, and is also equipped with a high frequency induction wire ring 11 which is a heating device, and the pedestal l
The compound semiconductor substrate 8 mounted on the surface of O can be heated to an epitaxial growth temperature, for example, 600 to 800°C.

(Description of Operation) Next, the characteristic operating principle of the present invention in the reaction tower structure of the embodiment of the present invention described above will be explained.

In the present invention, various raw material gases supplied into the reaction tube 2 through the gas inlet 6 at the upper part of the reaction tower 20 enter the mixing space 26 through the neck 22 of the spacer 21, where they are well balanced. Thereafter, the funnel portion 24 of the spacer 21 emits radiation at a wide angle through the opening 25 toward the compound semiconductor substrate 8 at the center of the pedestal. This raw material gas flow is simply indicated by 37 in the figure. At this time, pedestal 10
The mixed gas flow that has been subjected to temperature A near the semiconductor substrate on the surface 10a is guided by the funnel portion 24 to near the inner wall of the reaction tube 2, so that the rising gas 1138 is mixed with the raw material gas flow 37 that is being supplied. effectively separated as This rising gas flow 38 is prevented from rising along the spacer 21 in the reaction tube 2 due to the partition wall 28, but is forced to flow downward along the cooled tube wall and is rapidly discharged from the lower υ1 gas flow 34. In this way, since the temperature rising gas flow is guided downward, the raw material gas passing through the flow path regulating spacer 21 is not affected by these temperature rising gases, and the heat radiation of the pedestal 10 is also controlled by the spacer 21. It can be shielded by
The low temperature region streamline 37 of the raw material gas flow and the high temperature region streamline 38 of the rising gas flow can be completely separated. Because of this,
The temperature of the mixed gas can be maintained low until it reaches the surface of the compound semiconductor substrate 8, and therefore, the harmful thermal decomposition reaction of each component of the mixed gas can be suppressed to a minimum.
Good epitaxial growth on a compound semiconductor substrate can be performed.

Further, the above-described shielding spacer 35 prevents heat radiation from the surface 10a of the pedestal 10 from reaching the flow path regulating spacer 21.
Since the double gas flow 38 is effectively guided to the vicinity of the inner wall of the reaction tube 2, the Sarapacer 35 can further effectively enhance the above-mentioned effects of the present invention. I can do it.

Further, the sheath pipe 31 provided to cover the pedestal 10 prevents the mixed gas flow from flowing into the lower gas regulation area 32 as described above, and prevents the pedestal surface from flowing into the lower gas regulation area 32.
Since the sheath pipe 31 has a structure in which the heated dregs that are in contact with other surfaces other than 0a are discharged from the dedicated gas discharge 1"7, the sheath pipe 31 also makes the effects of the present invention described above more complete and effective. It can be increased to

(Effects of the Invention) As explained in the embodiment shown in FIG. It prevents harmful thermal decomposition reactions from occurring before reaching the substrate surface, quantitatively ensuring the ratio of each component element involved in epitaxial growth, and also prevents harmful fine powder generated by high-temperature mixed gas from becoming a compound. By preventing the material gas from falling onto the surface of the semiconductor substrate and evenly supplying the raw material gas to the surface of the compound semiconductor substrate at low temperature by emitting it over a wide angle, good crystallinity, surface flatness, and conductive properties can be achieved. It is possible to achieve an excellent effect that cannot be seen in conventional apparatuses, such as being able to grow an epitaxial growth layer having a high reproducibility with good reproducibility.

The semiconductor thin film growth apparatus of the present invention improves the crystal properties of epitaxial crystal layers used as constituent materials for high-efficiency light-emitting devices, ultra-high-speed FET devices, and integrated devices thereof, so that device performance can be improved and device performance can be improved. This can greatly contribute to improving manufacturing yields, etc.

It is clear that the present invention is not limited only to the embodiments described above. For example, the structure of the waste flow path regulating device may be another structure. This effectively separates the spent or unwanted gas stream at elevated temperature from the feed gas stream, and also guides the separated rising gas stream downward along the inner wall of the reaction tube where it is being cooled. Guide 4
It would be good as long as it has a structure that allows you to get 1 out of 1.

Furthermore, this reaction column can be constructed using other materials than quartz glass.

Further, the partition wall may be formed integrally with the flow path regulating spacer, or may be formed separately. Further, this partition wall may be configured to completely suppress the gas flow between the upper gas regulation area and the lower gas regulation area, or may be configured such that the gas flow is such that it does not heat the gas passage regulation spacer. It is preferable to have a good configuration and arrangement.

Furthermore, instead of providing a partition, the outer diameter of the enlarged portion may be made approximately equal to the inner diameter of the reaction tube, and the lower end of the enlarged portion may be placed on the brim-like projection.

Furthermore, the structure and support method of the shielding spacer and sheath tube may be different from each other.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view FA showing a conventional semiconductor thin film growth apparatus. FIG. 2 is a schematic cross-sectional view showing an embodiment of the semiconductor thin film growth apparatus of the present invention. l...Reaction tower, 2...Reaction tube 3...Outer tube, 4.5...Inflow/discharge pipe 6...
Gas inflow pipe, 7... Waste discharge pipe 8... Compound semiconductor substrate, 9... Support body 10... Pedestal, lo
a...Pedestal surface 11...High frequency guide wire ring,
12... Menu member 13... Convection of mixed gas flow, 14... Mixed gas flow 20... Reaction tower, 21.
...Flow path regulating spacer 22... Neck portion 23 of flow path regulating spacer... Enlarged portion 24 of flow path regulating spacer... Funnel section 25 of flow channel regulating spacer... Opening of funnel section, 26...・Gas mixing space 27...Upper gas regulation area, 28...Partition wall 29.38...Protrusion,
30... Upper exhaust gas port 31... Sheath pipe, 31
a...Opening 32 of the sheath pipe...Lower gas regulation area,
33... Sheath pipe support 34... Lower exhaust gas port
35...Shielding spacer, 35a...Central opening 35b of shielding spacer...Slope portion 35c of shielding spacer...Opening 35d of shielding spacer...Bending portion 37 of shielding spacer...Source gas flow , 38...Rising gas. Figure 1 Figure 2

Claims (1)

[Claims] 1. A reaction tube having a gas inlet and a gas outlet, and a pedestal disposed inside the reaction tube and having a surface on which a compound semiconductor substrate can be placed facing the gas inlet. A semiconductor thin film growth apparatus for organometallic compound pyrolysis, comprising: a cooling device provided outside the reaction tube for cooling the reaction tube; and a heating device ξ for heating the compound semiconductor substrate. In this method, the gas flow regulating device is disposed in the reaction tube, and the gas flow regulating device includes an enlarged portion forming a space for combining 4R of raw material gas supplied from the gas inlet; A funnel part is provided continuously in the ampullae and radiates and supplies raw material gas toward the compound semiconductor substrate mounted on the surface of the pedestal, and also includes a funnel part for separating temperature-increasing dregs and raw material dregs, It further comprises a flow path regulating spacer disposed between the waste inlet and the surface of the pedestal, and further comprising a lower exhaust gas port on the gas discharge port side of the reaction tube. Semiconductor thin film growth equipment. 2. The semiconductor thin film according to claim 1, wherein the gas flow regulating device has a shielding spacer in a gap between the flow channel regulating spacer and the pedestal. growth equipment. 3. A patent claim characterized in that the gas flow path regulating device includes a sheath pipe that covers the pedestal except for a portion of the compound semiconductor substrate on the surface of the pedestal and communicates with the gas discharge port. The semiconductor thin film growth apparatus according to item 1. 4. The gas flow regulating device has a partition wall that vertically partitions a space between the outer wall of the flow regulating spacer and the inner wall of the reaction tube. Semiconductor thin film growth equipment.