JPH026389A - Semiconductor thin film vapor phase growth equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a compound conductor thin film growth apparatus jξ, and more particularly to a semiconductor thin film growth apparatus δ in which the supply direction of the supply gas flow relative to the substrate is lost.

[Prior Art] Compound 1'-conductors currently occupy an important position as materials for optoelectronics. GaAs,
Epitaxy methods for growing compound semiconductor thin films such as AeAs include LPE, VPE, MBE, and MOCVD.
There are laws etc. In particular, the MBE method and MOCVD method can grow mixed crystal semiconductors that are not in a thermodynamically stable state in some cases, so they are particularly useful as core technologies for making full use of the potential of compound single conductors. Attention has been paid.

In recent years, it has been thought that it would be difficult to do so without using the MBE method.
By being able to achieve thin film epitaxial growth of 11-sized particles (200A or less) using the MOCVD method, the conventional MOCVD method is a cheaper device4 compared to the MBESlc device, and has a high productivity. DaJj
Coinciding with the characteristics such as being a process, it has become a downstream method for forming compounds 1", conductive thin films", and Vitakinyar.However, the thermal decomposition reaction mechanism and growth reaction theory of organometallics have not been clarified. As a result, there are many unresolved technical issues. In particular, the quality of the grown epitaxial layer tends to be greatly affected by the structure of the reaction tube, the method of supplying various gases such as raw materials, etc., which poses a major problem.
There are two types: vertical reaction tube method and horizontal reaction method.

For example, FIG. 6a is a cross-sectional view schematically showing a typical structure of a conventional vertical reaction method used in MOCVD. The reaction tube 1 has a double structure made of quartz glass, and an outer (II) tube 3 is provided around the inner reaction tube 2, and a water supply 114 and a drain port are provided above and below the outer tube 3. The structure is such that the outer wall of the reaction tube 2 is cooled by water cooling water flowing through the tube 5.Then, in the -F section of the reaction tube, an inlet 6 for various gases such as raw materials is connected to the epitaxial layer formation. -4 organometallic gases (e.g. TMG, TMA, etc.) and hydride gases (e.g. AsHs, PH, etc.) are
The structure is such that the necessary gases, which are supplied to the reaction tube 2 along with Hl, He, Ar, etc.) and which did not contribute to the reaction, can be discharged from the exhaust gas [17]. , F, and the compound conductor substrate 8 on which the epitaxially grown layer is formed are placed in the reaction tube 2.
It is arranged on the upper surface 10a of a carbon susceptor 10 held by a support rod 9 containing a thermocouple for temperature detection. This is heated to 600°C to 800°C by a high frequency induction coil 11 of a heating device installed on the outer periphery of the outer tube 3.
It can be heated to.

Furthermore, as a vertical reaction tube method, it is the 6th! I! There is a barrel-type reaction tube, as shown in Jb, which can grow a large number of substrates at the same time. Further, a horizontal reaction tube type reactor having the same structure as that shown in FIG. 6a is shown in FIG. 7.

In such a conventional vertical reaction tube structure, during epitaxial growth, 11 -L: r near the carbon susceptor
1, the gas temperature near the compound semiconductor substrate and carbon susceptor rises, and strong thermal convection occurs in the introduced gas, so that the mixed raw material gas that contributes to epitaxial growth is thermally decomposed before reaching the substrate, causing the substrate to deteriorate. It does not cause any negative effects such as poor controllability of the ratio of elemental components when reaching the surface and increase in clutter. When the gas flow becomes convection, it becomes a major obstacle to obtaining in-plane uniformity and high quality epitaxially grown layers on the substrate surface. Figure 8 1, t,
In the reaction and tube structure of FIG. 6a, when the carbon susceptor is heated, the thermal convection of the gas caused by the ambient temperature is shown.

Since the introduced gas is matured by the carbon susceptor, buoyancy occurs and an epitaxial layer 1+M is formed 4-
(!) This shows that a thermal decomposition reaction occurs before it reaches the substrate.Then, because the gas d is not uniform on the substrate, a temperature distribution occurs, and thermal convection causes the film to decompose. This suggests that the problem of not being able to control thickness, composition, etc. is serious.
Even in the horizontal reaction tube system shown in the figure, the epitaxial growth b'j
In order to achieve high uniformity, uniformity, and homogeneity of ≠λ−1, this is a serious problem that must be overcome.6 [Problem that the invention aims to solve] As a result of conducting intensive research to solve these problems, we found that, in particular, while supplying the compound to the conductor substrate using low-temperature raw material gases, we also supplied high-temperature gases that did not contribute to film growth after the reaction. A thin film that is configured to reliably separate residual raw material gas, carrier gas, or other inconvenient gases from the raw material gas on the substrate surface and exhaust it, and that has high uniformity, homogeneity, and high quality. It is possible to realize a growth layer. Therefore, it is an object of the present invention to provide a thin film growth apparatus capable of supplying raw material gas at an appropriately low temperature such that harmful reactions do not occur and appropriately controlling the flow of the supplied gas within a reaction tube. With the goal. Another object of the present invention is to provide an apparatus for obtaining a highly homogeneous and high quality grown semiconductor thin film. Here, "highly homogeneous" means "uniform film thickness distribution, uniform composition distribution, and uniform distribution of other electrical and optical properties."
It means that. Furthermore, "high quality" means "good quality from a crystallographic point of view and good crystallinity."

In this specification, "supply gas" means ``various gases such as raw materials.''

[Means for Solving the Problems] The present invention provides a reaction tube equipped with a supply gas introduction pipe and a gas exhaust port, and a support means (carbon nanotube) for mounting a compound semiconductor substrate disposed inside the reaction tube. In the semiconductor thin film growth apparatus, the semiconductor thin film growth apparatus includes a heating device for heating the compound semiconductor substrate, an outer tube provided outside the reaction tube for cooling the reaction tube, and a heating device for heating the compound semiconductor substrate. In order to utilize the heating gas flowing in contact with the substrate, the gas inlet is installed at the bottom, and the gas exhaust [1 is installed in the second part, and one of the gas inlets is installed at the bottom. Between the opening and the support means, a cylindrical flow path means for uniformly supplying the supply gas to the plate is disposed, and the gas that does not contribute to the reaction is quickly discharged. The flow of gas supplied into the reaction tube from the cylindrical channel means is directed to a conductive thin film growth apparatus in which the gas inlet structure is arranged perpendicularly to the substrate. Preferably, a cylindrical carrier gas flow path means is provided concentrically around stage f of the cylindrical flow path.Furthermore, the support means on which the substrate is mounted is integrated and rotates, and further, Preferably, a thin film growth layer with high homogeneity can be obtained.

The semiconductor thin film growth apparatus of the present invention comprises a reaction tube equipped with a supply gas inlet pipe and a gas exhaust port, a carbon sahibuter equipped with a compound semiconductor substrate arranged inside the reaction tube, and a carbon sahibuter mounted outside the reaction tube. The reaction tube is provided with an outer tube for cooling the reaction tube and a heating device for heating the compound semiconductor substrate. Then, inside the reaction tube, the heated gas flowing in contact with the substrate mounted on the carbon susceptor is heated so as to match the thermal convection caused by the buoyancy.
Install the supply gas inlet at the bottom and exhaust the gas []
can be installed on top. Furthermore, in this gas introduction structure, a cylindrical flow path means is provided between the gas introduction port and the support means so that the supplied gas flows uniformly over the substrate surface. The structure is such that the gas that is supplied and does not contribute to the reaction is quickly exhausted from the vicinity of the substrate surface. Therefore, the supplied gas flows perpendicularly to the substrate surface, and the gas that does not contribute to the reaction quickly flows toward the supporting means, that is, the side surface of the semiconductor. A gas of a constant composition and concentration is always supplied near the semiconductor surface, and the grown semiconductor thin film is highly homogeneous and of high quality.

Further, a cylindrical carrier gas flow path means is arranged around the cylindrical flow path means to further stabilize the flow of the supplied gas and to ensure uniform growth of the semiconductor thin film.

In addition, it is preferable that the support means on which the substrate is mounted be integrated and rotate on its own axis, so that the surface of the substrate rotates with respect to the fAE fluctuation of the supplied gas. Therefore, the gas supplied to the substrate surface becomes uniform, and the grown r-conductor thin film becomes uniform and homogeneous.

[Function] In the semiconductor thin film growth apparatus of the present invention, the raw material gas is supplied from the f direction by 1 Vl, L, and since the raw material gas is heated, it has buoyancy, and the thermal convection Jj direction of the gas and the −
・Because of this, the flow of raw material gas is uniform on the epitaxial growth surface of the semiconductor thin film (plate surface - L).
The temperature distribution also becomes uniform. Therefore, the growth layer of the semiconductor thin film becomes homogeneous, and as a result, the thin film that is grown has a uniform thickness, a uniform composition distribution, and other uniform electrical and optical properties. Therefore, a semiconductor thin film with better crystallographic quality can be produced.

Next, the semiconductor thin film vapor phase growth apparatus of the present invention will be explained using a specific example, but the present invention is not limited to the following example.

[Example] No. 11yJ is a 2-4 cross-sectional view of an example of the semiconductor thin film growth apparatus of the present invention. In this figure, the invention is shown in a simplified manner for easier understanding. The reference numbers used in the figures correspond to those used in the prior art described above.

In reaction case 1, a double structure made of quartz glass was used.
An outer tube 3 is provided around the outside of the reaction tube 2, and the outside of the reaction tube 2 is water-cooled by supplying cooling water from the water supply port 4 provided at the top of the tube 3 to the drain port 5. As shown in the figure, the gas inlet 6 for supplying gas into the reaction tube 2 is provided at the bottom, and the gas tJ[] 7 is provided at the top. The carbon susceptor 10 is arranged so that the carbon susceptor 10 is arranged so that the flow of the supply gas hits the surface of the substrate 80 placed there at right angles.
The flow of the supply gas is from the lower part to the upper part through the gas cylindrical channel means 12, and the substrate 8 is arranged at right angles thereto. That is, the gas introduction into the reaction tube 2 [1
The stage 6 has a gas cylindrical channel means 12 for the supply gas and is arranged at the bottom of the reaction tube 2 . This cylindrical flow path means 12 is provided perpendicularly to the carbon susceptor 10 from the gas inlet means 6 to the vicinity of the carbon susceptor 10.
The open portions of the IT path means 12 are arranged at appropriate intervals ξ4.

The removable cylindrical cup 14, the support rod 9 and the force holder 10 are suitably fixed as shown. In this specific example, the substrate 8 is capable of fixing one 2-inch wafer.

By providing the gas cylindrical flow path means 12 as described above, after supplying the raw material gas etc. to the carbon susceptor 10 and the substrate 8, the part where the gas is radiated and exhausted at a wide angle (i.e., the gas expansion part) 15 and a portion 16 that can be separated from the source gas (ie, portion Ili portion) is formed in the reaction tube 2. The gas expansion section 15 connects the gas cylindrical flow path means 12 (and 13
) is heated in contact with one of the carbon susceptors 10 and the surface of the substrate 8, and as it rises to the top, contributing or not contributing to epitaxial growth, it is affected by the surrounding gas flow. Preventing mixed flows 11:
role.

-JT thermally decomposes and rises, and the products generated by the reaction of reactive W, raw gas, etc., which did not contribute to growth, land on the inner wall of reaction tube 2. However, the separating section 16 also plays the role of collecting the deposits that fall down.

Historically, according to the present invention, the Kirriya gas cylindrical flow path means 13 is provided outside the periphery of the gas cylindrical flow path means 12 (j), so that the above effects can be further improved. The gas rises, hits the surface of the substrate 8, etc., and keeps the surrounding area in a steady state so that a stable gas flow path can be maintained so as not to form convection that would reverse the flow.

The conductor thin film forming apparatus of the present invention further includes a conventional J/
Like f, it has a double tube structure, and the reaction tube 2 is cooled by water or other cooling medium.

Furthermore, it is equipped with a high-frequency induction coil 11 as a heating device to maintain the necessary growth temperature for epitaxial growth (for example,
Only the carbon susceptor 10 and the substrate 8 can be heated to 600°C to 800°C.

The operating principle of the reaction tube structure according to the present invention in the apparatus of the specific example below will be explained next.

In the semiconductor thin film growth apparatus of the present invention, the flow of various supply gases such as raw materials can be ideally controlled even when compared to conventional apparatuses, for example, the reaction tube type shown in FIGS. 6 and 7.

Immediately, since the direction of the flow jj of the gas from the introduction L'5 and the direction of convection of the flow of the gas heated and buoyant by the carbon susceptor 10 etc. coincide, the epitaxial growth surface (i.e., the substrate 8 Since the gas flow on the surface of the substrate 8 becomes uniform and the temperature distribution on the surface of the substrate 8 also becomes uniform, the growth layer becomes homogeneous.

FIG. 2 shows an example of the flow of the supply gas according to the apparatus of the present invention from a heat transfer engineering point of view. According to this, it can be seen that the supply gas flows in a laminar flow to the surface of the carbon susceptor 10 (substrate 8) in the apparatus shown in FIG. On the other hand, gas expansion 8? ! The gas discharged to 15 flows in the directions of pT and F to cool the outside of reaction tube 2, forming a vortex as shown. This vortex can be prevented from mixing with the mixed gas.

That is, in the apparatus 4 of the present invention, as shown in FIG. 1, the raw material gas cylindrical channel means 12 is provided perpendicularly to the surface of the substrate 8 and at an appropriate interval.

Furthermore, at the same time, the gear rear gas cylindrical flow path means 13 is
, are provided around the source gas flow path as shown in FIG.

Therefore, in the t-conductor thin film growth apparatus of the present invention, the substrate 8 is placed at right angles to the flow of various gases such as raw materials introduced through the introduction 11 means 6 and created by passing through the cylindrical flow path means 12 and 13. The arrangement is the most important feature of the present invention.

Furthermore, a feature of the present invention is that a carrier cylindrical channel means 13 is provided in order to eliminate the influence of the gas convection section 17 shown in FIG.

In addition, support rod 9, carbon susceptor 10. The substrates 8 and ':J/P 14 can be integrally fixed and rotated, so that the composition, concentration, etc. of the supply gas supplied from the right angle can be further averaged, and furthermore, it can have high homogeneity. A compound semiconductor thin film growth layer is obtained.

Furthermore, FIG. 3 shows a case where the carbon susceptor 10 and the substrate 8 are not oriented at a 1u angle with respect to the flow of various gases such as introduced raw materials. When such an arrangement structure is adopted,
It becomes impossible to form a highly homogeneous growth layer on a large area substrate surface. In other words, when a heated carbon susceptor or substrate (solid) is placed in a mixed gas flow (fluid), from the perspective of fluid dynamics, the fluid is completely static on the solid surface. At a point away from the solid surface, the fluid velocity increases rapidly and remains constant throughout the flow. That is, at some distance from the solid surface, the velocity in the fluid becomes high and becomes equal to the velocity of a constant velocity flow as the distance increases. The same thing applies to temperature; the temperature of a solid surface becomes rapidly lower at points far away from the solid surface. In this way, areas where the velocity and temperature gradient of a fluid are steep are called a velocity boundary layer and a temperature boundary layer, respectively.The velocity boundary layer and the temperature boundary layer are closely related, and the solid and fluid This has an important effect on heat transfer between The velocity boundary layer includes a laminar boundary layer and a turbulent boundary layer, and heat transfer to a flow on a solid surface with a laminar boundary layer and heat transfer to a flow on a solid surface with a turbulent boundary layer. By comparison, the case with a turbulent boundary layer has a much greater heat transfer.
For this reason, when the flow direction is angled or horizontal (as shown in Figures 3a and b), the 1-
As shown in the figure, a gas flow flows in the flow direction , when the layer thickness develops beyond a certain point, the flow becomes turbulent. Point B is the point where the flow changes to turbulence, and this point is called the transition point.

When the flow changes to turbulence, the heat transfer coefficient increases rapidly as shown in the figure. Furthermore, downstream from the transition point, this boundary layer develops, so that heat escape from the substrate becomes increasingly large. This layer is the turbulent boundary layer. The phenomenon shown in Figure 4 generally occurs, and the angle of the substrate surface relative to the gas flow is important in the reaction tube of the conductor thin film forming apparatus. The two boundary layers with different properties coexist within the substrate surface, and the temperature distribution and growth layer thickness distribution will be created depending on how heat escapes.

), (If a temperature distribution occurs within the plate surface, it becomes difficult to obtain a highly homogeneous growth layer. For a substrate surface with a large volume, the length of the substrate surface along the flow It can be seen that as the number increases, it becomes more significant.

Therefore, it is important to unify the velocity boundary layer into either laminar flow or turbulent flow, and as shown in the embodiment of the present invention,
Placing the substrate surface perpendicular to the gas flow is effective for achieving a highly homogeneous epitaxial growth layer on a large area substrate.

Furthermore, in the thin film growth apparatus of the present invention, as shown in FIG.
In order to eliminate the convection portion 17 and control the gas flow, the Kirriya gas cylindrical flow path means 13 is necessary and effective.

Furthermore, as a modification of the specific example shown in FIG.
5 is a top view from the direction of the gas inlet means 6, and shows a large number of substrates 8 incorporated in the carbon susceptor 10. Each substrate 8 rotates on its own axis, and The mounted part 18 rotates further. That is, it is a view of the carbon susceptor 10 having the revolution portion 18 viewed from below. By rotating each cutting board and causing the entire cutting board to revolve, the composition, concentration, etc. of the supply gas that comes into contact with it can be made uniform.

If the present invention described in L. below is applied to the growth of semiconductor thin films, it is possible to prevent the effects of thermal decomposition of various raw material gases before they reach the compound semiconductor substrate in the MOCVD reaction tube. The gas heated in contact with the heating section has buoyancy, and thermal convection occurs due to the buoyancy, which is actively used to exhaust the gas to the gas expansion section, thereby preventing the gas from reaching the substrate. By arranging the substrate at right angles to the mixed gas, a uniform temperature distribution is formed within the surface of the substrate, which prevents the gas from mixing with the raw material gas before it reaches the gas. It is possible to grow an epitaxially grown layer with good reproducibility, which has high homogeneity with good crystallinity, surface flatness, electrical properties, etc. even on the substrate, and has high quality. It exhibits excellent effects that cannot be seen with other growth equipment.

The t-conductor growth apparatus of the present invention is particularly effective for manufacturing compound semiconductors, but it is also useful for manufacturing high-efficiency light-emitting devices, high-speed FETs, and their integrated devices as basic materials or structures. It is also effective for forming things. That is,
Since the characteristics of the epitaxially grown layer can be improved, it can make a significant contribution to improving the performance of manufactured devices and the yield rate of device manufacturing.

It is clear that the growth apparatus of the invention is not limited only to the embodiments described above; for example, the cylindrical channel means for the flow of the feed gas can also be used in other configurations. In other words, in a reaction tube where the gas flow is upward from the top, the substrate is perpendicular to the gas flow, and the structure is such that the flow of unnecessary gas and the flow of useful gas are effectively separated. Yes, as long as the gas expansion part and the gas separation part have a structure in which each has a flow path.Furthermore, the reaction tube can be made of a material other than quartz.

[Effects of the Invention] Firstly, since the semiconductor thin film growth apparatus of the present invention is arranged so that the supply gas flows in the same direction as the direction of thermal convection, the supply gas can be supplied to the substrate surface in a stable flow; A tL-length device is provided that does not mix with the gas to be evacuated.Secondly, by locating the substrate surface at right angles to the flow of the supply gas, high homogeneity can be achieved even for large area substrates. Thirdly, to provide a growth apparatus that can obtain an epitaxially grown layer that is suitable for use in epitaxial growth. Thirdly, it is possible to prevent the supply gas from causing a thermal decomposition reaction before reaching the substrate surface and adversely affecting the growth layer, and to perform the reaction using thermal convection. To provide a growth apparatus that can exhaust gases that do not give rise to a certain amount of gas and prevent gases from flowing before and after reaching a substrate.Fourthly, in metal-organic compound vapor phase growth, large The conventional fj method is capable of producing a highly homogeneous and high quality epitaxial growth layer with good crystallinity, surface flatness, electrical properties, etc. with good reproducibility even on a substrate with a large area.
, technical effects such as providing an excellent i-conductor thin film deposition apparatus ξ which cannot be seen in the present invention were obtained.

[Brief explanation of the drawing]

FIG. 1 is a 4" sectional view showing a specific example of the semiconductor thin film growth apparatus of the present invention. FIG. 2 is an explanatory diagram showing an example of thermal convection in the semiconductor thin film growth apparatus of the present invention. FIG. 3 is a 4' explanatory diagram showing the flow of the raw material gas that is not according to the present invention, and FIG. This is the case of a substrate placed in water at rM. Fig. 4 is an explanatory cross-sectional view showing the flow of source gas and the surface of the grown thin film. Fig. 5 is an apparatus for growing a conductive thin film of the present invention. 4 - Showing a cross section of a reaction tube for growing multiple semiconductor thin films'
1. FIG. 6 is a sectional view showing a vertical reaction tube type (a) and a barrel type vertical reaction tube type (b) as conventional semiconductor thin film growth apparatuses. FIG. 7 is a cross-sectional view showing a horizontal reaction tube system of a conventional semiconductor thin film forming apparatus. Figure 8 shows thermal convection of raw material gas in a conventional vertical reaction tube system. This is the fourth diagram. [Removal of codes of main parts] 2906 Reaction tube 391. Cooling outer tube 600. Gas inlet port a3. ．． Exhaust port 8, Semiconductor substrate 10, Carbon susceptor 11, Heating device 4 12), Gas flow pipe 13, Carrier flow pipe 15, Gas expansion section

Claims (3)

[Claims] (1) A reaction tube equipped with a supply gas introduction pipe and a gas exhaust port, a support means (carbon susceptor) for mounting a semiconductor substrate placed inside the reaction tube, and a reaction tube provided outside the reaction tube. In a semiconductor thin film growth apparatus comprising an outer tube for cooling the tube and a heating device for heating the semiconductor substrate, in the reaction tube (using convection of heated gas flowing in contact with the substrate), Gas inlet at the bottom,
The gas exhaust port is installed at the top, and a cylindrical flow path means is arranged between the gas inlet and the support means to uniformly supply the supply gas to the substrate surface, thereby contributing to the reaction. The semiconductor thin film is characterized in that a gas inlet structure is arranged so that the gas that does not pass through the substrate is immediately discharged, and the gas supplied from the cylindrical flow path means into the reaction tube is directed at right angles to the substrate. growth equipment. (2) The semiconductor thin film growth apparatus according to claim 1, further comprising a cylindrical carrier gas flow path means around the cylindrical flow path means. (3) The semiconductor thin film growth apparatus according to claim 1 or 2, wherein the support means for mounting the substrate is integrated and rotates on its axis.