JPH06291050A - Vapor growth si film and method and device for vapor growth - Google Patents

Abstract

PURPOSE:To form an improved Si film which does not incorporate a fine flake or mound by forming a single-crystal Si film which is the Si film formed in one piece on a wafer while a negative potential is applied to the wafer by the vapor growth by thermal decomposition of SiH4. CONSTITUTION:A bell jar body 1 is removed from the surface of a substrate 1. Then, a wafer 3 where Si film is allowed to grow, namely Si wafer, is placed on a susceptor 2. Then, after the bell jar body 1 is fitted to the surface of the substrate 8 airtightly, the pressure inside of the bell jar body 1 is evacuated and set to approximately 0.2 Torr. Then, a heat source 4 is operated and the wafer 3, etc., are heated to the retained at a required temperature and at the same time a negative potential and a positive potential are applied to the wafer 3 and the bell jar body 1 by a potential application means 5. Then, single-crystal Si film is deposited and is allowed to grow on the surface of the water 3 after thermal decomposition inside the bell jar body 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Si film formed by vapor phase growth, a vapor phase growth method for this Si film, and an apparatus suitable for vapor phase growth of a Si film.

[0002]

2. Description of the Related Art A Si single crystal film grown on a surface of a single crystal substrate has attracted much interest as a constituent of, for example, a transistor element. This type of Si single crystal film is generally formed on the wafer surface by vapor phase growth such as low pressure CVD. By the way, as a means for forming a Si single crystal film by a vapor phase growth method, generally, the following are summarized as follows: (a) thermal decomposition method, (b) unequalization method, (c) reduction method It is divided into

(A) Pyrolysis method, SiH ₄ → Si + 2H ₂ growth temperature: 1000 to 1100 ° C., growth rate: 5 to 10 μm / min, (b) Unequalization method, 2SiH ₂ Cl ₂ → Si + SiCl ₄ + 2H ₂ → 2Si + 4HCl growth temperature: 1050 to 1,150 ° C., the growth rate: 10~15μm / min, (c) reduction _{method, 2SiHCl 3 + 2H 2 → 2Si} + 6HCL growth temperature: 1,100-1,150 ° C., the growth rate: 5 to 10 [mu] m / min,

[0004]

However, in the formation of the Si single crystal film by the conventional vapor phase growth method, the following practically inconvenient problems are recognized.

First, in the case of (a) the thermal decomposition method, it is easy to form a good quality epitaxial layer (film) with few crystal defects at a relatively low temperature, but on the other hand, Si microcrystals deposited in the vapor phase are formed on the wafer ( For example, it tends to adhere to the surface of a single crystal si wafer), and the adhered Si microcrystals (micro Si flakes) form a region called “mound” in the subsequently grown Si film, and the crystal structure is distorted. However, it causes the formation of a film. That is,
It is preferable that the thickness of the growth film be up to about 10 μm, but if the thickness is larger than that, there is a problem that it is not suitable for forming semiconductor elements.

On the other hand, in the case of (b) the nonuniformization method and (c) the reduction method, the adhesion of fine Si flakes is avoided or reduced by the etching effect of HCl generated during the vapor phase growth. (a) Although the problems seen in the case of the thermal decomposition method are solved, there are problems in cost, such as preparation of raw materials, working environment, mass productivity, and corrosion resistance of growth equipment.

The present invention has been made in view of the above circumstances, and is a single crystal Si film that does not contain (contains) fine flakes or mounds, a method for forming a high-quality Si film, and an apparatus suitable for carrying out the forming method. For the purpose of providing.

[0008]

A single crystal Si film according to the present invention is a Si film integrally formed on a wafer surface,
The Si film is characterized by being formed by vapor phase growth by thermal decomposition of SiH ₄ in a state where a negative potential is applied to the wafer, and the vapor phase growth method of the Si film according to the present invention is Means for mounting a wafer in the region, means for applying a negative potential to the case body or wafer forming the vapor phase growth region, and SiH ₄ gas supplied to the wafer surface to which the negative potential has been applied. And a step of depositing and growing a Si film by thermal decomposition, and further, a vapor phase growth apparatus for a Si film according to the present invention has a SiH ₄ gas supply port and an exhaust port. A case body provided with the susceptor, a susceptor on which the wafer placed in the case body is placed, a heating heat source capable of heating and holding the wafer placed on the susceptor at a predetermined temperature, and a susceptor mounted on the susceptor. Potential applying means for applying a negative potential to the placed wafer, Characterized by comprising comprises.

According to the present invention as described above, when the negative potential is applied to the substrate to be grown in the vapor phase growth of Si using SiH ₄ (monosilane) gas as a raw material,
This is based on the finding that the adhesion phenomenon of fine flakes precipitated in the gas phase to the substrate to be grown is effectively avoided and the formation of mounds is greatly reduced or eliminated.

[0010]

As described above, the Si vapor-phase growth film according to the present invention is heated by the negative potential applied to the wafer during the process of forming the film on the growth substrate (wafer) surface. The microflakes (Si microcrystals) that decompose and precipitate in the vapor phase preferentially or selectively move to the case side in a so-called vapor phase growth chamber, so Si that is deposited / deposited on the wafer surface The problem of the formation of mounds in the film is completely avoided. In other words, since a good quality single crystal Si film having a film thickness and no distortion in the crystal structure is held,
It can be said that it is suitable for manufacturing or configuring various semiconductor devices.

[0011]

Embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 is a sectional view showing a structural example of a main part of a single crystal Si film vapor phase growth apparatus according to the present invention. Reference numeral 1 is a bell jar body (case body), 2 is inside the bell jar body 1. This is a susceptor on which the wafer 3 on which the arranged Si film is grown is placed, and is made of a conductive material such as graphite or SiC. Further, 4 is a heating heat source capable of heating and holding the wafer 3 mounted on the susceptor 2 at a predetermined temperature, for example, a heating heat source including a high-frequency coil, and 5 is a negative heat source for the wafer 3 mounted on the susceptor 2. Is a potential applying means for applying a positive potential to the bell jar main body 1 and the like, and the airtight bell jar main body 1 is airtight to a base 8 having a SiH ₄ gas supply port 6 and an exhaust port 7. It is attached in a detachable manner in the form of a casing. In other words, this Si film vapor phase growth apparatus is characterized in that potential applying means 5 for applying a negative potential to the wafer 3 mounted on the susceptor 2 and a positive potential to the bell jar body 1 and the like is additionally provided. Since it is attached, the basic configuration and structure, and the operation are no different from the conventional vapor phase growth apparatus.

Next, an example of a method of forming a single crystal Si film by the Si film vapor phase growth apparatus having the structure shown in FIG. 1 will be described. First, the bell jar body 1 is removed from the surface of the base 8, and a wafer 3 on which a Si film is grown, for example, a Si wafer is placed on the susceptor 2. Next, the bell jar body 1
After air-tightly mounting the base on the surface of the base 8, the pressure inside the bell jar main body 1 is exhausted and set to about 0.2 torr through the exhaust port 7, while the heat source 4 for heating is operated and the required temperature such as the wafer 3 is reached. In addition to heating and holding, the potential applying means 5 applies a negative potential to the wafer 3 and a positive potential to the bell jar body 1 and the like. While rotating the susceptor 2 in the direction of the arrow in the figure, a mixed gas of, for example, SiH ₄ 75sccm and H ₂ 75sccm is supplied from the SiH ₄ gas supply port 6 and pyrolyzed in the bell jar body 1 to produce a single crystal. A Si film is deposited and grown on the surface of the wafer 3.

During the thermal decomposition of SiH ₄ and the deposition / growth of the single crystal Si film on the surface of the wafer 3, a negative potential is applied to the wafer 3 and a positive potential is applied to the bell jar body 1 by the potential applying means 5. Therefore, as shown schematically in FIG. 2, Si microcrystals (microflakes) that precipitate in the gas phase and are easily negatively charged are selectively and preferentially attached to the side of the bell jar main body 1 that has a positive potential. The risk of adhesion to the surface of the wafer 3 is completely eliminated. In other words, since the minute flakes do not adhere during the deposition / growth of the single crystal Si film on the wafer 3 surface, the mound generation caused by the minute flakes is inevitably eliminated during the film formation, and the crystal structure is distorted. High quality (high quality) single crystal Si suitable for forming semiconductors
It will function as a film.

In the above, in applying the negative potential to the wafer 3, the bell jar main body 1 and the bell jar main body 1 may be provided with the positive potential and the susceptor 2 may be provided with the negative potential. 2 and the wafer 3 may be partitioned (isolated) by an insulator and a positive potential may be applied to the susceptor 2. Further, a base to which a positive potential is applied may be arranged separately from the bell jar, and flakes may be deposited on the base. Further, the susceptor 2 mounted and arranged in the bell jar main body 1 and the wafer 3 mounted on the surface of the susceptor 2 may have a plurality of divided structures, and a plurality of embodiments may be adopted.

[0016]

As described above, according to the present invention,
The microflakes (Si microcrystals) deposited in the vapor phase due to the thermal decomposition of SiH ₄ during the vapor phase growth while the substrate (wafer) to be grown is applied with a negative potential are for so-called vapor phase growth. The bell jar and the case side of the machine are preferentially or selectively transferred. Therefore, the problem that a mound or the like is generated in the single crystal Si film deposited / formed on the surface of the substrate to be grown is completely avoided. In other words, the film thickness is of good quality with no distortion in the crystal structure.
Since the Si film is held, it can be said that a material suitable for manufacturing or configuring various semiconductor elements can be provided easily and in mass production.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structural example of a main part of a single crystal Si film vapor phase growth apparatus according to the present invention.

FIG. 2 is a cross-sectional view schematically showing the behavior of fine flakes deposited in the vapor phase by thermal decomposition in an embodiment example of vapor deposition of a Si film according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Bell jar main body 2 ... Susceptor 3 ... Growth substrate (wafer) 4 ... Heating heat source 5 ... Potential applying means 6 ... Raw material gas supply port 7 ... Exhaust port 8 ... Base

Claims (4)

[Claims] 1. A Si film integrally formed on a wafer surface, wherein the Si film is formed in a state where a negative potential is applied to the wafer.
A vapor-grown Si film formed by vapor-phase growth of iH ₄ by thermal decomposition. 2. A means for mounting a wafer in a vapor phase growth region, a means for applying a negative potential to a case body forming the vapor phase growth region, and a wafer surface to which the negative potential is applied. A means for depositing and growing a Si film by supplying SiH ₄ gas and thermally decomposing it.
Film vapor deposition method. 3. A means for mounting a wafer in a vapor phase growth region, a means for applying a negative potential to a wafer arranged in the vapor phase growth region, and a wafer surface to which the negative potential is applied.
A method for vapor phase growth of a Si film, comprising means for supplying SiH ₄ gas and thermally decomposing it to deposit and grow the Si film. 4. An airtight case body having a SiH ₄ gas supply port and an exhaust port, a susceptor for mounting a wafer arranged in the airtight case body, and a wafer mounted on the susceptor to a predetermined size. And a potential applying means for applying a negative potential to the wafer mounted on the susceptor.