JPH02166725A - Manufacture of polycrystalline silicon on semiconductor substrate - Google Patents

Abstract

PURPOSE:To reduce the diameter of the particle of particle shaped fused silicon by bringing reactive gas having etching effect for the fused silicon into the particle shaped fused silicon during the time until the sprayed and jetted fused silicon reaches a semiconductor substrate. CONSTITUTION:A nozzle 34 is provided at the upper part of the center of the surface of a single crystal silicon substrate 21. V grooves are formed on the substrate 21. The inside of a spray device 38 is filled with an inert gas B. The single crystal silicon substrate 21 is heated with a second heat source 37, and this state is maintained. Then, a turn table 36 is rotated, and another inert gas A is imparted on the fused surface of fused silicon 31. Then reactive gas C is made to flow in the direction of the tip of the nozzle 34 through a gap 32c and jetted through a jetting port 34b. Then, the fused silicon 31 is atomized and jetted through a jetting port 34a at the tip of the nozzle 34. The fused silicon becomes atomized fuzed silicon 31a. The silicon 31a is directed toward the single crystal silicon substrate surface 21. The temperature of the atomized fused silicon 31a becomes high by a first heating source 33. The silicon 31a drastically reacts with the reactive gas C in the vicinity of the output port of the nozzle 34. The outer part of the atomized fused silicon 31a is etched, and the diameter of the particle becomes more smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming a polycrystalline silicon layer on a semiconductor substrate, such as a single crystal silicon substrate, through an insulator. The present invention relates to a method for manufacturing a thick polycrystalline silicon layer that serves as a support layer for a body separation substrate.

[Conventional technology]

Conventionally, a CVD method using a reduction reaction of tl of chlorinated silane has been known as a method for rapidly forming a thick polycrystalline silicon layer suitable for the support of a dielectric separation substrate. Japanese Patent Application No. 63-134175 proposed a method of spraying silicon from a nozzle onto a single-crystal silicon substrate to form a polycrystalline silicon layer of a predetermined thickness.

FIG. 2 is a schematic diagram of a spray device used to carry out the above method. In the figure, 21 is a single crystal silicon substrate, 25 is a polycrystalline silicon layer, 31 is molten silicon,
32 is a melting tank for melting silicon; 33 is a first heating source installed around the melting tank 32 and made of a high-frequency heating coil or the like to heat the melting tank 32; 34 is a melting tank 3
A nozzle 31a is provided at the bottom of the nozzle 3 and injects molten silicon 31 toward the surface of the single crystal silicon substrate 21.
It was sprayed from 4! L-shaped molten silicon, 35 is nozzle 3
A turntable 35a, which is installed directly below the turntable 4 and rotates with the single crystal silicon substrate 21 placed thereon, is the substrate surface of the turntable 35 and always maintains a horizontal state with respect to the rotation of the turntable 35. 36 is a second heating source installed around the turntable 35 and made of a high-frequency heating coil or the like to heat the single crystal silicon substrate 21; 37 is a second heating source for introducing an inert gas, which will be described later, into the spray device, which will be described later. An inlet, 38 is a spray device whose components include the above-mentioned melting tank 32, first heating source 33, turntable 35, second heating source 36, and inlet 37, and A is applied to the melting surface of molten silicon 31. A gas inert to the molten silicon 31 (for example, argon), B is a spray device 38 from the inlet 37.
Indicates the inert gas filled inside.

Although the melting tank 32 is schematically shown in FIG. 2, its details are as in FIG. 1. That is, FIG. 1 shows the melting tank 32,
In particular, it is a structural diagram showing enlarged details of the nozzle 34 provided at the lower part of the nozzle 34, in which 32a is the melting tank 32.
The outer melting tank 32b is the inner melting tank of the melting tank 32. The inner melting tank 32 has an injection hole 34a at the tip of a nozzle for injecting molten silicon. Outer melting tank 32a
The inner melting tank 32b maintains a constant interval and forms a gap 32C, and for example, the inner melting tank 32b is adjacent to the injection hole 34a.
An annular injection hole 34a that surrounds and ejects spray gas.
has. C is a spray gas that is injected from the injection hole 34a to inject and atomize the molten silicon 31, and an inert gas is used.

FIG. 3 is a diagram showing the manufacturing process of the dielectric isolation substrate.

First, a V-groove 22 is formed on a single-crystal silicon substrate 21 using photolithography or the like (FIG. 3(a)).
. Next, after forming an isolation oxide film 23 on the V-groove 22, a polycrystalline silicon thin film 24 as a seed crystal is formed thereon using the CVD method (FIG. 3(b)). Then, the spray device 38 is filled with an inert gas, and the silicon is melted by heating from the first heating #, 33, and this molten silicon 31
Inert gas C is applied to the melting surface and the gap 32c at O1~0,5
By applying a pressure of Kg/cm2, the nozzle 34
From there, granular molten silicon 31a is injected in the direction of the single crystal silicon substrate 21 surface on the turntable 35.

This granular molten silicon 31a is a polycrystalline silicon thin film 24.
The molten silicon layer 25a is formed by reaching the top.

The single-crystal silicon substrate 21 is heated to about 1400°C by a second heat source 36, and the turntable 3
5 is rotating, a uniform molten silicon layer 25a is formed on the polycrystalline silicon thin film 24. When the molten silicon layer 25a reaches a predetermined thickness, the granular molten silicon 81a
In addition, the heating of the second heating source 36 is stopped (FIG. 3(C)).

Then, the molten silicon layer 25a is cooled and solidified to form a polycrystalline silicon layer 25, and then the single crystal silicon substrate 25a is
A dielectric material having isolation islands 26 of single crystal silicon separated from each other by mechanically and chemically polishing the surface opposite to the polycrystalline silicon layer 25 on the surface of the polycrystalline silicon layer 25 until the tip of the V groove 22 is exposed. A separated substrate is obtained (FIG. 3(d)).

[Problem to be solved by the invention]

However, in the method for manufacturing a polycrystalline silicon layer described above, the grain size of the granular molten silicon is larger than the depth of the grooves, and the wettability with flat areas on the polycrystalline silicon thin film is poor; Cavities may occur. When the dielectric isolation island is formed, the cavity within the V-groove is exposed, causing a problem in that it lacks the function as a dielectric isolation substrate. In addition, because the grain size of granular molten silicon is large, its heat capacity is large, and when forming a polycrystalline silicon layer, thermal distortion and crystal defects may occur due to the temperature difference between the dropped molten silicon and the single crystal silicon substrate. .

The present invention has been made to solve the problems of the prior art described above, and the method of claim 1 prevents the generation of cavities in the V-groove, and also prevents the generation of thermal strain and crystal defects on the semiconductor substrate. An object of the present invention is to provide a method for manufacturing a polycrystalline silicon layer that can prevent this.

In addition to the above object, the method of claim 9 also aims to provide a method capable of obtaining a polycrystalline silicon layer at high speed.

[Means for solving problems]

The method according to claim 1 of the present application is a method of forming a polycrystalline silicon layer by spraying molten silicon onto a semiconductor substrate and cooling and solidifying it on the semiconductor substrate, in which the sprayed granular molten silicon is applied to the semiconductor substrate. The present invention is characterized in that the particle size of the granular molten silicon is reduced by contacting the granular molten silicon with a reactive gas having an etching effect on the molten silicon until the molten silicon reaches the top. The method of claim 9 is a method of forming a polycrystalline silicon layer by spraying molten silicon onto a semiconductor substrate having a groove and cooling and solidifying the molten silicon on the semiconductor substrate, wherein the molten silicon on the semiconductor substrate has a predetermined shape. The thickness is achieved by contacting the granular molten silicon with a reactive gas having an etching effect on the granular molten silicon until the sprayed granular molten silicon reaches the semiconductor substrate. , reducing the particle size of the granular molten silicon and, after reaching the predetermined thickness, spraying the injected granular molten silicon so that it reaches the semiconductor substrate without contacting the reactive gas; It is characterized by

[Effect]

In the method according to claim 1 of the present invention, the outer peripheral portion of the granular molten silicon injected from the nozzle reacts violently with the reactive gas and is etched to reduce the particle size. Therefore, by the time it reaches the semiconductor substrate, the grain size has become sufficiently small compared to the depth of the V-groove, so the inside of the V-groove is filled with granular molten silicon and hardly any cavities are formed. Furthermore, as the grain size decreases, the heat capacity decreases, and the possibility of thermal strain and crystal defects occurring during formation of the polycrystalline silicon layer decreases.

In the method of claim 9, a reactive gas is used for spraying until a predetermined thickness is reached (for example, until a V-groove is filled), and an inert gas is used for spraying after a predetermined thickness is reached. Since it is sprayed, the outer periphery of the granular molten silicon is not etched. Therefore, at this time, granular molten silicon having a relatively large particle size reaches the surface of the semiconductor substrate. Therefore, a polycrystalline silicon layer can be formed more quickly. As a result, the time required to form the polycrystalline silicon layer can be shortened.

〔Example〕

The present invention will be explained below with reference to the drawings. In this example, the manufacturing process diagram of the polycrystalline silicon layer and the schematic configuration diagram of the spray equipment used to form the polycrystalline silicon layer are the contents of Figures 1, 2, and 3 used to explain the conventional example. It is similar to

Embodiment of Chopsticks The first manufacturing method in this embodiment is to form an isolation oxide film and CV
After forming the polycrystalline silicon thin film 24 by the D method (third
(b)) The method is characterized in that a reactive gas having an etching effect on the molten silicon 31 is used as the spray gas C to spray the molten silicon.

That is, the nozzle 34 is installed above the center of the surface of the single-crystal silicon substrate 21 on which the V-groove 22 is formed. Then, the inside of the spray device 38 is filled with inert gas B, and the single crystal silicon substrate 21 is heated to about 1100 to 1300° C. by the second heating source 37.
Heat to a temperature of and maintain this state. Next, the turntable 36 is rotated at a rotational speed of 50 to 1100 RP, and inert gas A is applied to the melting surface of the molten silicon 31 by 0.1 to 0.0 RP.
Apply with a pressure of 5 kg/cm2.

Next, a reactive gas C (for example, hydrogen chloride gas) as a spray gas is flowed into the gap 32c at a pressure of 0.1 to 0.5 Kg/cm2 toward the tip of the nozzle 34, and the injection hole 34b is
By spouting the molten silicon 31 from the nozzle 3
It is atomized and ejected from the injection hole 34a at the tip of 4, becomes granular molten silicon 31a, and is applied to the single crystal silicon substrate surface 21.
Head to.

The granular molten silicon 31a is heated to a high temperature by the first heating source 33, and reacts violently with the reactive gas C near the exit of the nozzle 34, and the outer periphery of the granular molten silicon 31a is etched to make the particle size smaller. The granular molten silicon 31a having a reduced particle size reaches the single crystal silicon substrate 21, and is adsorbed and deposited in the V-groove 22 or flat portion of the polycrystalline silicon thin plate 24. Granular molten silicon 31
Since a is sufficiently smaller than the depth of the groove 22, it fills the V groove 22 without creating a cavity within the V groove 22. When the polycrystalline silicon layer 25 reaches a predetermined thickness (for example, about 500 μm when the single crystal silicon substrate 21 has a diameter of 41 nch), the rotation of the turntable 36 is stopped and the supply of heat from the second heating source 37 is stopped. Stop and allow the molten silicon layer to cool and solidify.

A polycrystalline silicon layer 25 is thereby obtained.

In the above method, the particle size of the granular molten silicon 31a depends on the tip shape of the nozzle 34, the flow rate of the reactive gas C applied to the gap 32c, and the temperature of the molten silicon 31 in the melting tank 32. It is also possible to make the size about 10 μm.

In addition, reactive gas C is inert gas (for example, argon, etc.)
It is also possible to change the particle size by mixing and changing the mixing ratio.

Embodiment of Chopsticks λ Next, the method of the second embodiment will be explained. The method of this second embodiment consists of a step of injection of molten silicon, a first step and a second step.
It consists of stages.

In the first stage, a reactive gas is used for spraying as in the first embodiment. When a molten silicon layer of a predetermined thickness is formed by this, the process moves to the second stage. Whether a predetermined thickness has been reached is determined by the amount of molten silicon 31 dropped. The predetermined thickness here is, for example, such a thickness that the V-groove is filled with molten silicon.

In the second stage, the supply of the reactive gas C that was flowing into the gap 32c in the first stage is stopped, and instead, inert gas A is supplied at 0.1 to 0.
．． It is supplied to the gap 32c at a pressure of 5 kg/am2. As a result, the granular molten silicon 81a is no longer etched, and the granular molten silicon obtained in the first step, which has a larger particle size, reaches the single crystal silicon substrate. In the first step, a molten silicon layer 2 of a predetermined thickness is formed on the polycrystalline silicon thin film 24.
5a is formed and the V-groove 22 is filled, and there is no possibility that a cavity will be formed even if granular molten silicon 31a with a large particle size reaches there. On the other hand, as the particle size of the arriving granular molten silicon 31a becomes larger, the deposition progresses faster. Therefore, the time required to form the polycrystalline silicon layer can be shortened. Molten silicon layer 2 with a predetermined thickness
5a, the injection of the granular molten silicon 31a is stopped in the same manner as described above for the first embodiment, and further the heating from the second heat source 36 is stopped and the molten silicon layer 25a is
is cooled and solidified to form a polycrystalline silicon layer 25.

Example of Kakitan Next, the method of the third embodiment will be explained.

The spray device 38 is filled with inert gas A from the inlet 37 while being maintained at a reduced pressure (for example, 10 Torr), and the first
The method described in Example 1 and Example 2 is carried out.

By maintaining the inside of the spray device 38 at a reduced pressure, the wettability of the granular molten silicon 31a on the polycrystalline silicon thin film 24 is improved, so that it is easily adsorbed onto the polycrystalline silicon thin film 24, and the generation of cavities is further reduced.

In the above embodiment, the reactive gas C is supplied through the gap 32C, but it can also be supplied into the spray device 38 through an inlet 37 provided within the spray device 38. In this case, inert gas will flow through the gap 32c.

Further, the number of introduction ports 37 may be plural depending on the type of gas to be supplied.

〔Effect of the invention〕

As explained above, according to the present invention, the outer periphery of the granular molten silicon injected from the nozzle reacts with the reactive gas and is etched, so the particle size decreases and the V-groove is etched before reaching the semiconductor substrate. As a result, no cavity is formed in the V-groove on the polycrystalline silicon thin film.

Also, cavities are less likely to form in the flat portion. This eliminates the formation of cavities that previously occurred when the grain size of granular molten silicon was larger than the depth of the V-groove, and also reduces the grain size and heat capacity, causing thermal distortion and crystal defects due to temperature differences with the semiconductor substrate. will almost never occur.

In addition, spraying is carried out in two stages, first by contacting the granular molten silicon sprayed from the nozzle with a reactive gas to reduce the grain size by an etching effect, and when the polycrystalline silicon layer reaches a predetermined thickness (V-groove). Since we decided to stop the supply of reactive gas (after filling) and stop etching, the grain size increases and the deposition rate of the polycrystalline silicon layer can be increased. It can save time.

In addition, by filling the spray device with an inert gas atmosphere under reduced pressure and spraying, the wettability between the granular molten silicon and the polycrystalline silicon thin film is improved, and therefore cavities are less likely to form, resulting in a good polycrystalline silicon layer. can be manufactured quickly.

31a... granular molten silicon, A...Inert gas, B...Inert gas atmosphere, C...Spray gas.

[Brief explanation of the drawing]

FIG. 1 is a schematic structural diagram of a nozzle, FIG. 2 is a schematic structural diagram of a spray device, and FIG. 3 is a diagram of a manufacturing process of polycrystalline silicon on a semiconductor substrate. 21... Semiconductor substrate, 25... Polycrystalline silicon layer, 31... Molten silicon,

Claims (17)

[Claims] (1) In a method of forming a polycrystalline silicon layer by spraying molten silicon onto a semiconductor substrate and cooling and solidifying it on the semiconductor substrate, the period until the sprayed granular molten silicon reaches the semiconductor substrate A polycrystalline silicon layer on a semiconductor substrate, characterized in that the grain size of the granular molten silicon is reduced by contacting the granular molten silicon with a reactive gas having an etching effect on the molten silicon. How to form. (2) The method according to claim 1, characterized in that the reactive gas is used as a spray gas to contact the granular molten silicon. (3) In the method according to claim 2, a first injection hole through which the injection means used for the spray injection communicates with the melting tank of the molten silicon and ejects the molten silicon;
A method comprising: a second injection hole adjacent to the first injection hole for ejecting the gas for spray injection; and ejecting the reactive gas from the second injection hole. (4) In the method according to claim 1, the spraying means and the semiconductor substrate are placed in an inert gas atmosphere with respect to the molten silicon, and the spraying is performed in the inert gas atmosphere. How to characterize it. (5) The method according to claim 4, wherein the inert gas atmosphere is under reduced pressure. (6) The method according to claim 1, wherein the semiconductor is single crystal silicon. (7) The method according to claim 1, wherein the semiconductor substrate is a single crystal silicon substrate covered with a dielectric film. (8) The method according to claim 1, characterized in that, prior to forming the polycrystalline silicon layer by the spraying, a polycrystalline silicon thin film is formed by a CVD method. (9) In a method of forming a polycrystalline silicon layer by spraying molten silicon onto a semiconductor substrate having a groove and cooling and solidifying it on the semiconductor substrate, the molten silicon on the semiconductor substrate reaches a predetermined thickness. Until now, the granular molten silicon was sprayed by contacting the granular molten silicon with a reactive gas having an etching effect on the granular molten silicon before the granular molten silicon reached the semiconductor substrate. After reducing the particle size of the silicon and reaching the predetermined thickness, spraying is performed so that the reactive gas reaches the semiconductor substrate without contacting the injected granular molten silicon. A method for forming a polycrystalline silicon layer on a semiconductor substrate. (10) In the method according to claim 9, the reactive gas is used as the spray gas until the predetermined thickness is reached, and after the predetermined thickness is reached, the granular molten silicon is used. A method characterized by using an inert gas that has no etching effect. (11) In the method according to claim 10, the injection means used for the spray injection includes a first injection hole that communicates with the melting tank of the molten silicon and spouts out the molten silicon; a second injection hole adjacent to which the spray gas is ejected, and the reactive gas is ejected from the second injection hole until the predetermined thickness is reached. After that, the inert gas is ejected from the second injection hole. (12) In the method according to claim 11, the spraying means and the semiconductor substrate are placed in the inert gas atmosphere with respect to the molten silicon, and the spraying is performed in the inert gas atmosphere. A method characterized by: (13) The method according to claim 12, wherein the inert gas atmosphere is under reduced pressure. (14) The method according to claim 9, wherein the semiconductor is single crystal silicon. (15) The method according to claim 9, wherein the semiconductor substrate is a single crystal silicon substrate covered with a dielectric film. (16) In the method according to claim 9, prior to forming the polycrystalline silicon layer by the spraying, CVD
A method characterized by forming a polycrystalline silicon thin film by a method. (17) The method according to claim 9, wherein the predetermined thickness is such that the V-groove is filled with molten silicon.