JPS6334920A - Vapor growth apparatus - Google Patents

Abstract

PURPOSE:To uniformize the concentration gradients of material gas on the surface and periphery of a crystal substrate thereby to easily obtain a thin film crystal having a uniform thickness by supplying gas to be reacted substantially perpendicularly from below the surface of the substrate to be held by a susceptor. CONSTITUTION:Reaction gas which contains material gas is supplied from a reaction gas supply port 9 of a reaction furnace body 1 toward the surface of a crystal substrate 7 held on the lower surface of a susceptor 5. The supplied reaction gas is guided by a diffuser 13 to arrive at the substrate 7, heated to a predetermined temperature by a high frequency induction heater 17, reacted on the surface of the substrate 7 rotated by a rotational shaft 3, decomposed to become a crystal and grown on the substrate 7. The reaction gas which is finished to react and decompose on the substrate rises in a space 15 between the peripheral edge 5a of the susceptor 5 and the inner wall 1b of the body 1, and is led from an outlet 11 at the top of the body 1 to an exhaust gas processor.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a semiconductor vapor phase growth apparatus.

(Prior Art) As a conventional vapor phase growth apparatus of this type, there is one shown in FIG. 2, for example. That is, this vapor phase growth apparatus has a reactant gas supply port 101 at the top.

Reactor body 105 having a reaction gas outlet 103 at the bottom
It is equipped with This reactor body 105 includes a diff user 106 that is gradually expanded from the supply port 101 at a predetermined expansion rate, in other words, at a constant expansion angle α. This reactor body 10
A susceptor 109 for holding a crystal substrate 107 is installed within the diff user 5 at the same height as the enlarged end (lower end) of the diff user 106 . The susceptor 109 is the bottom wall 1 of the reactor body 105.
It is attached to a rotating shaft 111 that is rotatably supported by the motor 05a, and is rotated by a motor or the like (not shown). A high frequency induction heating device 113 is provided around the reactor body 105 as a heating means for heating the crystal substrate 107.

Then, a reactive gas (raw material gas and carrier gas) containing the raw material gas to be crystallized is introduced into the reactor body 105 from the reactive gas supply port 101 . The introduced reaction gas is guided by a diffuser 106, held on a susceptor 109, and heated to a predetermined temperature (
Flows toward the crystal substrate 107 heated to 700° C. to 800° C.).

Crystal growth is performed by reaction and decomposition action on the surface of the crystal substrate 107. The reaction gas that has been reacted and decomposed flows through the space 115 between the peripheral edge 109a of the susceptor 109 and the inner wall 105b of the reactor body 105, and is led from the reaction gas outlet 103 to an exhaust gas treatment device (not shown).

Incidentally, in this type of vapor phase growth apparatus, uniformity of the crystal film thickness on the surface of the crystal substrate 107 is required on the premise of mass production.

However, in the conventional vapor phase growth apparatus, since the diff user 106 gradually expands at a constant expansion angle α, the gap between the peripheral edge 109a of the susceptor 109 and the inner wall 105b of the reactor body 105 increases. The cross-sectional area of the space 115 becomes sharply narrower than the cross-sectional area of the upper part of the susceptor 109. Therefore, the reaction gas introduced into the reactor body 105 is accelerated when flowing through the space 115, and the isoconcentration line of the raw material gas contained in the reaction gas is located at the periphery of the susceptor 09 as shown in FIG. The portion 109a is swept downward. Therefore, the first isodensity line is the peripheral edge 1 of the susceptor 109.
09a, the film thickness distribution formed on the surface of the crystal substrate 107 has a monotonically increasing profile from the center to the outer periphery of the susceptor 109, as shown in FIG. 4, and the uniformity of the crystal film thickness is The problem was that it got worse.

In order to avoid this rapid acceleration of the reaction gas, for example, a method of increasing the internal pressure of the reactor body 105 to reduce the overall gas flow rate can be considered, but in this case, the density of the reaction gas increases, and as a result, The buoyant force acting on the heated gas near the crystal substrate increases, generating large thermal convection.

This thermal convection then disturbs the flow field near the crystal substrate.

This hindered the growth of thin film crystals with uniform thickness.

(Problem that the invention attempts to solve) As mentioned above, in the conventional vapor phase growth apparatus.

The concentration gradient of the raw material gas becomes non-uniform around the crystal substrate, and when the pressure of the reaction gas is increased to avoid this, thermal convection occurs, and in the end it is not possible to obtain a thin film crystal with a uniform film thickness distribution.

The present invention has been made in view of the above circumstances, and its purpose is to make the concentration gradient of the raw material gas on the surface of the crystal substrate and the surrounding area uniform, so that thin film crystals with uniform thickness can be easily obtained. An object of the present invention is to provide a phase growth device.

[Structure of the invention]

(Means for Solving the Problems) In the vapor phase growth apparatus of the present invention, the gas to be reacted is supplied from below substantially perpendicularly to the surface of the crystal substrate held by the susceptor.

(Function) In the device configured in this way, the gas for one reaction is supplied from the bottom to the top, so the heat generated when the pressure is increased in order to reduce the flow rate of the gas is reduced. No convection occurs.

Therefore, iso-concentration lines parallel to the crystal substrate, that is, uniform concentration gradients in the vertical direction are realized over the entire surface of the crystal substrate.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a cross-sectional view of a vapor phase growth apparatus according to the present invention,
A susceptor 5 supported on a rotating shaft 3 is disposed within the reactor body 1 . On the lower surface of this susceptor 5, a crystal substrate 7 is placed.
It is fixed via a presser plate 23, for example, with screws or the like. The rotating shaft 3 and the susceptor 5 are 1. The upper bottom wall 1 of the reactor body 1
A is rotatably supported by a thrust bearing 25 and rotated and driven by a motor (not shown) or the like.

A supply port 9 for supplying a reaction gas containing a raw material gas into the reactor body 1 is provided at the lower central portion of the reactor body 1 .

The reaction gas that is supplied upward from the supply port 9, passes through the first reaction gas passage 13, and reaches the vicinity of the crystal substrate 7 reacts and decomposes on the lower surface of the crystal substrate 7 while changing the flow direction from the vertical direction. change horizontally. A presser plate 23 having a smooth shape is placed on the outer periphery of the susceptor 5 so as not to disturb the gas flow. .

The vehicle is led to an exhaust gas treatment device (not shown).

In this embodiment, one reactor body 1 is equipped with a differential user 13 that is gradually expanded upward from the supply port 9 at a predetermined expansion rate. It is not limited. The reactor body 1 is supported by a furnace support 27, and around the reactor body 1, a crystal substrate 7 held by a susceptor 5 is heated to a predetermined temperature (7
A high frequency induction heating device 17 is provided as a heating means for heating to 00°C to 800°C.

In the vapor phase growth apparatus configured in this manner, the reaction gas containing the raw material gas is directed from the reaction gas supply port 9 of the reactor body 1 toward the surface of the crystal substrate 7 held on the lower surface of the susceptor 5. Supplied. This reaction gas is, for example, organometallic trimethylgallium ((CH*)mGa), a group II element.
It is composed of a mixed gas of arsine gas (AS-H3), a hydride of group V elements, and hydrogen gas (H3). The supplied reaction gas is guided by the diffuser 13 and reaches the top of the crystal substrate 7, where it is heated to a predetermined temperature (700°C to 800°C) by the high frequency induction heating device 17 and the crystal rotated by the rotating shaft 3. Reaction 1 on the surface of substrate 7
It decomposes, becomes a gallium arsenide (GaAs) crystal, and grows on the surface of the crystal substrate 7. The reaction gas that has completed the reaction and decomposition on the surface of the crystal substrate 7 rises in the space 15 between the peripheral edge 5a of the susceptor 5 and the inner wall 1b of the reactor body 1, and reaches the exhaust port 11 in the upper part of the reactor body 1. The gas is then led to an exhaust gas treatment device (not shown).

FIG. 2 shows another embodiment of the present invention, and shows the first embodiment.
The same parts as those in the figures or corresponding parts are given the same reference numerals, and the description thereof will be omitted.

In FIG. 2, a plurality of crystal substrates 7 (eg -2, 4, etc.) can be held on the lower surface of the susceptor 5, and is suitable for mass production.

FIGS. 3 and 4 are sectional views showing still another embodiment, and the same or corresponding parts as in FIGS. 1 and 2 are given the same reference numerals, and the explanation thereof will be omitted.

In the case 1 configured as shown in FIG. 3, the supply port 9
The reaction gas that is supplied from the crystal substrate 7 and reaches the vicinity of the crystal substrate 7 undergoes reaction and decomposition on the surface of the crystal substrate 7 while changing its flow direction from the vertical direction to the horizontal direction. An axially symmetrical exhaust duct 21 is provided on the outer periphery of the susceptor 5, and the gas after one reaction passes through the exhaust port 11'.

The vehicle is led to an exhaust gas treatment device (not shown). In this embodiment, the upper surface 21a of the exhaust duct 21 is
is set at substantially the same position as the lower surfaces of the crystal substrate 7 and the susceptor 5 in the vertical direction.

According to the configuration of this embodiment, the exhaust duct 21 is provided so that the concentration gradient of the source gas in the vertical direction is uniform on the crystal substrate 7, as shown in FIG. 4.

A nearly ideal, uniform concentration gradient is achieved, and therefore a thin film crystal with a uniform thickness can be easily obtained. In conventional equipment, this occurs near the outer periphery of the susceptor.

This is because the reaction gas is rapidly accelerated and the concentration distribution is disturbed, whereas in the configuration of this embodiment, the acceleration and deceleration of the reaction gas is very gradual.

Note that the exhaust ports 11 for the gas after the reaction may be provided on the entire outer circumference of the reactor body 1, or may be provided in plural on the outer circumference of the reactor body. If a plurality of pumps are provided, it is preferable to exhaust the air approximately axially symmetrically.

Further, for mass production, a plurality of crystal substrates 7 may be held on the lower surface of the susceptor 5.

According to the configuration of the present invention, the crystal substrate 7 is heated to a high temperature.
is located above the relatively low-temperature reaction gas supply port 9, so even if the pressure is increased to reduce the gas flow rate, thermal convection due to the density difference is unlikely to occur. Therefore, thin film crystals with uniform thickness can be easily obtained. Further, since the susceptor 5 is provided perpendicularly to the reactive gas supply port 9, the reactive gas is supplied vertically to the crystal substrate 7 on which a thin film is to be grown, so that the reaction efficiency of the reactive gas is good. Also.

Increasing the pressure increases the thin film growth rate.

A thin film crystal of a predetermined thickness can be obtained in a short time.

〔Effect of the invention〕

As detailed above, according to the present invention, a thin film crystal having a uniform thickness can be easily obtained.

[Brief explanation of the drawing]

8g1 is a cross-sectional view showing one embodiment of the vapor phase growth apparatus of the present invention, FIGS. 2 to 4 are cross-sectional views showing other embodiments of the vapor phase growth apparatus of the present invention, and FIG. A cross-sectional view of a conventional vapor phase growth apparatus, FIG. 6 shows an isoconcentration diagram of source gas in a conventional vapor growth apparatus, and FIG. 7 shows a film thickness distribution obtained by a conventional vapor phase growth apparatus. It is an explanatory diagram. DESCRIPTION OF SYMBOLS 1... Reactor body, 5... Susceptor, 7... Crystal substrate, 9... Supply port, 11... Exhaust port% 13...
Deaf user. 17... High frequency induction heating device% 23... Holding plate. Agent Patent Attorney Nori Ken Yudo Takehana Kikuo Pu Figure 1 q Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (3)

[Claims] (1) A vapor phase growth apparatus that deposits a vapor phase growth layer by supplying a gas to be reacted onto the crystal substrate while heating the crystal substrate, comprising a passageway for guiding the gas upward from the gas supply port. A reactor body, a susceptor that is disposed above the passage in the reactor body and holds the crystal substrate substantially perpendicular to the gas supply direction, and an exhaust port that discharges the gas after the reaction. A vapor phase growth apparatus characterized by: (2) The vapor phase growth apparatus according to claim 1, wherein the exhaust port is provided radially in the reactor body near the periphery of the susceptor. (3) The vapor phase growth apparatus according to claim 2, wherein the exhaust port is provided at substantially the same plane as the lower surface of the susceptor and the crystal substrate.