JPS6010621A - Depressurized epitaxial growing equipment - Google Patents

Abstract

PURPOSE:To make extremely high purity silicon single-crystal grow by forming at least the surface of a furnace wall of a reaction furnace with Si or SiC. CONSTITUTION:A reactive gas inlet 2 and a reactive gas outlet 3 are provided to a reaction furnace 1. Resistance heaters 4 are arranged around the reaction furnace 1 as furnace wall heaters. Wafers 6 are held on a holding means 5 in the furnace. Si or SiC is used as furnace wall material of the reaction furnace 1. With this constitution, the inside of the reaction furnace is depressurized to 5- 100Torr by evacuation through the outlet 3. Wafers 6 are heated to the temperature of approximately 1,100 deg.C. Reactive gas composed of SiHCl2 and PH3 is introduced with a carrier gas H2 into the furnace 1 through the inlet 2 and dispersed on the wafers 6 to make silicon single-crystal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reduced-pressure epitaxial growth apparatus in which a heating element is disposed around the outer periphery of a reduced-pressure reactor, and a silicon single crystal is grown on a substrate placed inside the reactor. In particular, the furnace wall surface is made of silicon (hereinafter referred to as Si) or silicon carbide (hereinafter referred to as SiC) and the furnace wall heating element is used to raise the temperature of the entire furnace body by heating the furnace wall. It is related to equipment.

Conventionally, in the field of semiconductor devices, low-pressure epitaxial growth equipment has been widely used for the production of silicon single crystals9. ,
It is known to be particularly advantageous for the growth of thin epitaxial layers, since autodoping can be avoided.

In the reduced pressure epitaxial growth apparatus, a reaction gas is passed through a reduced pressure reactor, and a heating element is disposed around the outer periphery of the reactor, and the wafer in the reactor is heated by the heating element. , a silicon single crystal is grown on the wafer, and quartz (hereinafter referred to as 5i
n2 and ML) have been adopted.

However, if a furnace wall heating element made of a resistance heating element such as a nichrome wire heater is used as the heating element in the above-mentioned reduced-pressure epitaxial growth apparatus, the furnace wall itself is also heated by the heating element (hereinafter, such an apparatus will be referred to as a hot There was a drawback that 02 oozed out from the 5i02 which was the furnace wall material, forming a continuous nucleus on the wafer, and the crystal structure was disturbed. Furthermore, since the crystal structure of 5i02 is not dense, N2, etc. can permeate into the furnace from the outside by tracing the furnace wall, making the disturbance of the crystal structure even more serious. Ta.

In addition, flakes formed on the furnace wall due to an undesired reaction slip and fall from the furnace wall due to the difference in expansion coefficient between the old furnace wall and the flakes, and are deposited and mixed onto the wafer. It also had some flaws.

Moreover, the reaction temperature is high (approximately 1100℃), and the reactor sea material (
Since it is close to the melting point of Sin2), there was also the disadvantage that the furnace wall was softened and deformed, shortening the life of the equipment.

As a solution to the above-mentioned problems of the hot wall type, a cold wall type is used, which selectively heats only the wafers inside by irradiating infrared rays from the outer periphery of the reactor, without increasing the temperature of the reactor wall itself. However, in the cold wall type device, the infrared irradiation device is large, so it requires a large space and has the drawbacks of high cost.Furthermore, the infrared lamp has a short lifespan. Another drawback was that maintenance work was complicated.

In view of the problems such as deterioration of crystal quality caused by the structure of the hot wall type reduced pressure epitaxial growth apparatus based on the above-mentioned conventional technology, an object of the present invention is to coat at least the wall surface of the reactor wall with Si or SiC. By creating a structure in which the
The present invention aims to provide an excellent low-pressure epitaxial growth apparatus capable of growing silicon single crystals of extremely high purity.

The structure of the present invention in accordance with the above object is that a heating body is disposed around the outer periphery of a reactor into which a reaction gas is introduced, and in a reduced pressure epitaxial growth apparatus for growing a silicon single crystal on a wafer in the reactor in a vapor phase, the heating By using the body as a furnace wall heating body and forming the furnace wall of the reaction furnace from Si or [SiC, it is possible to eliminate the protrusion of 02 from the furnace wall when the furnace wall is heated, and further, It prevents flakes formed on the furnace wall from falling, and also eliminates softening and deformation of the furnace wall.
The gist of the invention is to make it possible to grow high-quality silicon single crystals with high purity, and further,
The structure of the second invention, which is common to the above invention, is that the furnace wall is formed of a laminated material in which both sides of a carbon layer are coated with Si or SiC layers, thereby achieving high performance without impairing the various effects of the invention. Although it is possible to grow silicon single crystals of high purity and high quality, it is possible to save expensive Si or SiC as a furnace wall material and to increase the mechanical strength of the reactor. The gist of this is that

Next, embodiments of the present invention will be described below based on the drawings.

1 and 2, a reactor 1 is provided with a reactant gas inlet 2 and a reactant gas outlet 3.
A resistance heating element 4 such as a nichrome wire heater is disposed around the outer periphery of the reactor as a furnace wall heating element.A support 5 is provided inside the reactor 1, on which a wafer is placed. 6 is supported. As the furnace wall material of the reactor 1, S
1 or SiC is used.

In the above configuration, the pressure inside the reactor 1 is reduced to 5 to 100 torr by exhaust air from the exhaust port 3, and the wafer 6 is heated to about 1100°C, and S i'Hc 12, PHs
A reaction gas consisting of ``is introduced into the furnace 1 through the inlet 2 together with the carrier gas (H2), and is scattered on the wafer 6 soil.
Silicon single crystal grows.

Moreover, as another embodiment, as shown in FIG. 3, the present invention can be applied to a reactor equipped with a heating zone and a cooling zone.

In the figure, the reactor 1 has a heating zone 7a and a cooling zone γb connected by a connecting ring 7c.
A cooling body 9 such as a Peltier effect element as a furnace wall cooling body is disposed around the outer periphery of the cooling zone 1b.

The support 5 is arranged so as to be able to reciprocate within the reactor T.

The furnace wall material in the heating zone 1a is made of Si or S.
iC is used as the furnace wall material in the cooling zone 1b,
The same S i02 as the conventional one is used.

In the above configuration, during single crystal growth, the support 5 is placed in the heating area la, the wafer 6 is heated by the resistance heating element 8, and the silicon single crystal is grown by the reaction gas. After the reaction is completed, the supply of the reaction gas is stopped, and the wafer 6 is moved to the cooling area γb and cooled there. At the same time, the carrier gas (N2) in the furnace γ is replaced with N2 gas, thereby preventing the carrier gas from igniting when the wafer 6 is taken out after cooling.

In this way, the use of expensive SL or SiC in the entire reactor is avoided, and these are used only in the heating region where it is not desirable to use 5io2 as a reactor wall material, making the entire device economical. Become something.

In the above embodiments, the wafer is supported by a support, but the present invention is not limited to this, and the wafer may be held on a thin plate-like susceptor supported horizontally in multiple stages in the furnace. There may be, and furthermore,
The multistage susceptor may be supported obliquely with respect to the gas flow direction. 1 Furthermore, in the above embodiment, a resistance heating element is used as the furnace wall heating element 4.8, but it is not limited to this, and the wafer inside the furnace is heated through heating of the furnace wall. All kinds of heating elements that raise the temperature are included in the furnace wall heating element referred to in this specification.

Next, a furnace wall of a reactor according to an embodiment of the second invention, which is related to the above invention, is extracted and shown in FIG. Nil
As a wall material of the reactor, S is applied on both sides of the carbon layer 10.
A laminate coated with i or SiC layer 11 can be used.

In the case where a Si layer is not formed in the upper B furnace wall material, 5
Using IC14 as a reaction gas, a Si crystal film is formed on the surface of the carbon layer by a gas phase reaction at approximately 1200°C. At this time, the Si crystal is only deposited and is not mixed with carbon. There is no chemical bond in the opening of

On the other hand, when forming 5iCJ, Si elements are sintered on the surface layer of the carbon layer by a gas phase reaction at about 1400°C using 5iC14 as a reaction gas. A compound of /Q> is formed on the surface layer of the carbon layer.

As described above, according to the present invention, in a low-pressure epitaxial growth apparatus for growing silicon single crystals on a wafer in the reaction furnace, the heating body is arranged around the outer periphery of the reaction furnace, and the heating body is used as the furnace wall heating body. By forming the reactor wall with St or SiC, 02 does not come out from the reactor wall during the low-pressure, high-temperature reaction because the reactor wall material does not originally contain 02. In addition, since the crystal structure of the furnace wall material is dense, gases such as N2 do not permeate through the furnace wall, and undesired nuclei are not formed on the wafer.
This has the excellent effect that no disturbance occurs in the crystal structure formed on the wafer.

In addition, the expansion coefficients of the flakes formed on the furnace wall and the furnace wall material are the same in the Si phase, and are very close to each other even in the SiC phase, so the flakes do not peel off from the furnace wall. Another effect is that high-quality silicon single crystals can be obtained by adhering to the wafer.

(10) Since SiC material is as high as 1500°C and about 4000°C, it is often softened and deformed at the reaction temperature (about 1100°C), which also has the effect of extending the life of the device.

Furthermore, according to a second aspect of the present invention, the above-mentioned effects of the present invention can be achieved by forming the front furnace wall with a laminate in which both sides of a carbon layer are coated with a Si layer or a SiC layer. In addition to the same effect as
The amount of i or SiC material used can be saved, and the presence of the carbon layer also has the effect of significantly increasing the mechanical strength of the furnace wall.

In addition, in the structure of this invention and the second invention that is common thereto, since the furnace wall becomes conductive in reaction M, unnecessary plasma is not generated inside the furnace body during the reaction process. It also has a positive effect.

Thus, the present invention has solved the problems of the prior art and made it possible to realize a hot wall type low pressure epitaxial growth apparatus for the first time.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing an embodiment of the invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, FIG. 3 is a side sectional view showing another embodiment, and FIG. FIG. 2 is a cross-sectional view of a main part of a second embodiment of the invention;

Claims (2)

[Claims] (1) A low-pressure epitaxial growth apparatus for growing a silicon single crystal on a wafer placed in the reactor, which is composed of a reactor whose interior is depressurized and a heating element disposed around the outer periphery of the reactor. A reduced pressure epitaxial growth apparatus characterized in that the heating body is a furnace wall heating body 4, and the furnace wall of the reaction furnace 1 is formed of Si or SiC. (2) A low-pressure epitaxial growth apparatus for growing silicon single crystals on a wafer placed in the reactor, which is comprised of a reactor whose interior is depressurized and a heating element disposed around the outer periphery of the reactor; The heating body is a furnace wall heating body 4, and the furnace wall of the reaction furnace 1 is coated with St or SiC on both sides of the carbon layer 10.
A low pressure epitaxial growth apparatus characterized in that it is formed by a vI layer body coated with layer 11.