JPS6345199A - Vapor growth device - Google Patents

Abstract

PURPOSE:To contrive to make film thickness of crystal growth layer uniform and to improve product yield, by arranging an approximately pyramidal susceptor in a bell-jar having outer peripheral length lessening from the top toward the bottom and setting a light reflecting structure of spherical surface of polygon at the outer peripheral part. CONSTITUTION:An approximately pyramidal susceptor 10 having the top part opposing to the side of a gas inlet 14 is set in a bell-jar 12 equipped with the gas inlet 14 and a gas outlet 16 in the vertical direction, bases 1 are supported and a reaction gas is introduced to a reaction chamber 15. The gas is heated by a high-frequency coil 7 set at the outer peripheral part and a crystal layer is grown in vapor by chemical reaction on the bases 1. In the vapor growth device of a barrel type having the constitution, the reaction chamber 15 consists of the bell-jar 12 in the form wherein the outer peripheral length is gradually lessened from the top toward the bottom, and the reaction gas is made uniform. Further, a light reflecting structure 31 having a reflecting face made of spherical surface of polygon is set at the position opposing to the bases 1 at the outer peripheral part of the bell-jar and radiation heat is efficiently sent to the surface of the bases 1. Temperature gradient of the bases 1 at both sides is corrected and bending and crystallographic slippage are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application This invention relates to the improvement of a vapor phase growth apparatus for vapor phase growth of a desired semiconductor thin film on a substrate through a chemical reaction, and to the improvement of a vapor phase growth apparatus for vapor phase growth of a desired semiconductor thin film on a substrate through a chemical reaction. In addition, by effectively utilizing the radiant heat from the heating element, the temperature distribution of the substrate is made uniform, the uniformity of the film thickness is improved, and crystallographic slippage of the substrate is prevented. The present invention relates to a vapor phase growth apparatus that can improve product yield.

BACKGROUND ART Today, in the mass production of integrated circuits, raw material gas is introduced from one side into a bell jar containing a substrate heated to high temperature, and a thin film of a specific composition is formed on the substrate by a vapor phase chemical reaction.
A vapor phase growth apparatus is used in which exhaust gas is discharged from the other end of a bell jar.

Generally, in a vapor phase growth apparatus, in order to uniformly form a thin film to the required thickness on a substrate, it is necessary to optimally select and maintain various factors such as temperature, pressure, gas concentration, and substrate surface. It is said that

Various types of vapor phase growth equipment, such as horizontal, vertical, and barrel types, have been developed based on the fluid dynamics of the raw material gas in the bell jar and the heating method of the substrate.
It is known that the uniformity of thin film thickness is adversely affected, and in particular, temperature differences between multiple substrates and temperature gradients between the front and back surfaces of each substrate can cause thermal stress on the substrates, crystallographic smearing, etc. It has been pointed out that this can lead to the production of
-50095).

The barrel-type vapor phase growth apparatus shown in FIG. 3 has the advantages of horizontal and vertical types, and the susceptor (2) that holds the substrate (1) and is rotationally driven has a substantially pyramidal shape consisting of a plurality of inclined surfaces. The raw material gas is introduced into the cylindrical reaction chamber (
5) and is discharged from a gas outlet (6) provided at the center of the lower closed bottom, and a high-frequency coil (7) is arranged around the outer periphery of the bell jar (3). Further, as shown in FIG. 4, in the case of the barrel type using the dome-shaped bell jar, all the bell jars are arranged upside down except that the susceptors (2) are tilted in the same direction.

In such a vapor phase growth apparatus, there is a tendency to increase the number of substrates processed in one batch, but uneven gas flow and uneven gas concentration distribution pose problems, so it is necessary to increase the uniformity of the substrates and susceptor, which are the heated bodies. For the purpose of heating, the distance between the high frequency coil (7) of the heating source and the susceptor (2) is adjusted,
High-rise: Measures such as controlling the total heat to the heated object by considering the arrangement method of the leather coil (7), making the temperature distribution on the substrate (1) uniform, and reducing the pressure. By increasing the gas flow rate and increasing the supply amount of raw material gas, the film on each substrate in the gas flow direction is increased! A method was taken to improve the non-uniformity of 7.

However, even with the above method, the non-uniformity of the gas concentration distribution cannot be resolved and the thickness of the grown thin film becomes non-uniform. Therefore, the susceptor is placed approximately parallel to the gas flow, and the gas concentration in the vertical direction on the substrate is fixed at 1IIJ. A method has been proposed (Japanese Unexamined Patent Application Publication No. 75999/1989) to supply supplementary raw material gas based on the results, but in order to perform such gas concentration pressure determination and automatic II charging in real time, sophisticated calculations are required. , 'J control was required, which caused some operational problems.

In addition, due to the raw material gas constantly flowing on the surface of the substrate (1) or depending on the thickness of the substrate, a temperature gradient occurs between the front and back surfaces of the substrate (1), causing the substrate to curve due to thermal stress, and the temperature at the center and periphery of the substrate to increase. There was a difference in product yield due to crystallographic slippage of the substrate.

For this reason, countermeasures have been taken, such as devising a method for holding the substrate in a susceptor (Japanese Patent Application Laid-Open No. 59-50095), but this did not fundamentally solve the temperature gradient between the front and back surfaces of the substrate.

Purpose of the Invention The present invention provides a vapor phase growth apparatus that can uniformize the substrate surface temperature, improve the uniformity of film thickness, prevent crystallographic slippage of the substrate, and improve product yield. It is an object.

Structure and Effects of the Invention As a result of various studies aimed at uniformly heating a substrate in a vapor phase growth apparatus, the present invention optimizes and secures the gas flow in the reaction chamber, and then heats the heated object (substrate). By actively utilizing the radiant heat from (and susceptor),
This eliminates the temperature gradient between the front and back surfaces of the substrate, greatly improving the uniformity of temperature distribution on the substrate, improving the uniformity of the formed thin film thickness, and preventing crystallographic slippage of the substrate, resulting in improved product quality. It was discovered that the retention rate was improved.

That is, this invention provides a bell jar with gas introduction and discharge ports provided in the vertical direction, and a substantially pyramid-shaped susceptor with its top facing the gas introduction port side, which allows chemical methods such as hydrogen reduction and thermal decomposition to be carried out. Due to the reaction,
In a barrel-type vapor phase growth apparatus for vapor phase growth of a crystal layer on a substrate, a reaction chamber is configured with a bell jar having a shape whose outer circumference gradually decreases from the gas inlet side toward the lower gas outlet, Furthermore, the vapor phase growth apparatus is characterized in that a light reflecting structure having a polyspherical reflecting surface is disposed on the outer periphery of the bell jar.

In this invention, the gas flow and concentration within the reaction chamber can be optimized by configuring the reaction chamber with a bell jar whose outer circumference gradually decreases from the gas inlet side toward the lower gas outlet. However, the relationship between the inclination and angle of the susceptor and the drawing inclination angle of the bell jar described above: Toge bell jar dimensions and susceptor shape 2 dimensions It is necessary to consider various conditions such as gas flow and gas flow, etc., and select appropriately.

The light reflecting structure, which is a feature of the present invention, heats the substrate to a required temperature with a high-frequency coil via a susceptor in such a vapor phase growth apparatus, and absorbs radiant heat from the substrate and the heated body of the susceptor. , it has the function of reflecting it in the desired direction without causing diffuse reflection and returning it to the substrate surface.This allows it to compensate for the temperature gradient on the front and back surfaces of the substrate that occurs in conventional equipment, so the substrate is curved and the surface temperature distribution is changed. Non-uniformity and crystallographic slippage are prevented from occurring.

The shape and dimensions of this light reflecting structure and the structure of the reflecting surface are appropriately selected depending on the type and configuration of the vapor phase growth apparatus to which it is applied. The above-mentioned effect can be obtained by arranging the light reflecting structure at a position facing the heated object, and by configuring the upper reflecting surface or the position facing the heated object of the light reflecting structure to be a polyspherical surface, the radiant heat is most efficiently transferred to the substrate surface. It is impossible to reduce it to .

In addition, the Ti'' quality of the light-reflecting rIW structure is preferably a material that does not induce high frequencies; for example, heat-resistant ceramics such as alumina can be used, and the reflective surface can be formed with a mirror finish, or gold, silver, Means such as depositing and forming a reflective film of rhodium or the like can be adopted.

DISCLOSURE OF THE INVENTION BASED ON DRAWINGS FIG. 1 is an explanatory diagram of a barrel-type vapor phase growth apparatus according to the present invention. FIG. 2 is a longitudinal sectional view of the pond vapor phase growth apparatus of the present invention.

In the air growth apparatus shown in FIG. 1, the susceptor (10) that holds the substrate (1) is composed of a plurality of slopes:
It is composed of a rectangular vertebrae, is rotatably held by being attached to a rotating shaft (11) suspended perpendicularly to a base, and is placed in a tulip-shaped bell jar (12). A member (13) that closes the upper opening of (12)
The raw material gas flows into the reaction chamber (1) from the gas inlet (14) provided in the
5) and is discharged from the gas outlet (16) provided at the center of the closed bottom of the bell jar (12).

The bell jar (12) has a shape in which the outer circumference gradually decreases from the gas inlet (14) side toward the lower gas outlet (16), and
A ceramic light-reflecting structure (31) whose inner reflective surface is a polyspherical surface is arranged in a layer opposite to the surface to which the light-reflecting structure (31) is attached. The high frequency coil (17) has this light reflecting groove structure (+
(31) is arranged on the outer periphery.

The barrel type vapor phase growth apparatus shown in FIG.
The holding susceptor (20) has the same substantially polygonal pyramid shape, and also has a rotating shaft (21) vertically supported on the base.
The bell jar (22), which is rotatably held and arranged to cover the bell jar, has a gas inlet (24) in the center of the head, and a horizontal outer circumference toward the lower opening. It has a shape in which the length decreases temporarily, and the raw material gas enters the reaction chamber (in the bell jar (22)) from the upper gas inlet (24).
25) A gas outlet (26) provided in a member or base that descends inside and closes the opening at the bottom of the bell jar (22).
more excreted.

Furthermore, so as to cover the entire bell jar (22),
A light reflection structure (32) made of a polyspherical surface of a ceramic shank is arranged, and a high frequency coil (27) of 8j5 sources is wound around the outer periphery of the structure (32).

As mentioned above, by making the shape of the bell jar (12x22) into a unique shape according to the present invention according to the slope, angle, etc. of the susceptor (10x20), there are the following advantages.

That is, in general, the raw material gas is heated and expands as it goes downward in the conventional cylindrical reaction chamber (5) (see Figure 3), which creates buoyancy and disrupts the flow velocity on the downstream side.
There was a tendency for the concentration of the raw material gas to be high on the upstream side and low on the downstream side, resulting in uneven film thickness formed on the downstream substrate. By making the shape of the reaction chamber (15 x 25) smaller, the cross-sectional area of the passage on the downstream side becomes smaller, so the flow rate becomes faster, the influence of buoyancy is reduced, and a uniform film thickness can be achieved.

Note that if the bell jar is made cylindrical and the inclination angle of the susceptor is made gentler, the situation is considered to be relatively similar to the above case, but the shape of the susceptor changes, the holding area of the substrate changes,
This is not preferable because the gas concentration also changes, which eliminates the problems mentioned above.

In addition, the light reflection structure r 3 l, 1 has its entire reflection surface, and the light reflection structure Qj' t:Yi structure 32) has its head 1 and bottom inner reflection surfaces, respectively, from the polyspherical surface (' In order to effectively return the radiant heat from the susceptor <10M20) and the substrate (1) to the substrate (1),
Since it is possible to compensate for the temperature gradient on the front and back surfaces of the convex slope,
It is possible to prevent crystallographic slippage from occurring due to the substrate being curved and the surface temperature distribution becoming non-uniform.

Example Using the barrel type vapor phase growth apparatus shown in Fig. 1, susceptor: hexagonal pyramid diagonal length upper side 250 mm, lower side 280 mm, rotation speed 6/min Bell jar: upper diameter 335 mm, lower diameter 310 mm
Light reflection IIW structure; diameter 435mm, high frequency coil and light reflection i, l, l; distance between structures: 20~
35mm Heating time: 1 hour Heating temperature: 1200°C1 Reaction time: 30 minutes Semiconductor f + gas;
・14. The return of radiant heat from the liquid heating body by the structure: +=: 25% of 71 1
A 5% reduction was achieved, and the average percentage on the substrate surface was improved, the crystallographic slippage was significantly reduced, and the product retention was improved by 8%.

In addition, compared to the conventional device with a cylindrical inflatable bell jar with a diameter of 335 mm, the formed thin film thickness was more uniform and the film thickness variation was reduced by 10%.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a barrel-type iron mesh growth apparatus according to the present invention. FIG. 2 is a vertical cross-sectional view of a pond vapor phase growth apparatus according to the present invention. 1 is a vertical cross-sectional view of a conventional barrel-type vapor phase growth apparatus; 1...substrate; 10.
20...Susceptor, 12.22...Quartz bell jar, 14,24...Gas inlet, 15.25...Reaction chamber, 16.26...Gas outlet, 17.27...
High frequency coil, 31.32...Light reflecting structure.

Claims (1)

[Claims] A substantially pyramid-shaped susceptor with the top facing the gas inlet is placed inside a bell jar with gas inlet and outlet ports in the vertical direction, and chemical reactions such as hydrogen reduction and pyrolysis are used to
In a barrel-type vapor phase growth apparatus for vapor phase growth of a crystal layer on a substrate, a reaction chamber is configured with a bell jar having a shape whose outer circumference gradually decreases from the gas inlet side toward the lower gas outlet, Furthermore, a vapor phase growth apparatus characterized in that a light reflecting structure having a polyspherical reflecting surface is disposed on the outer periphery of the bell jar.