KR100243348B1 - Selective single crystal thin film growth method without crystal defect and slope - Google Patents

Abstract

The present invention provides a selective single crystal growth method capable of preventing the presence of crystal defects and facets at the interface between the single crystal thin film and the silicon oxide film when the selective single crystal thin film is grown on the semiconductor substrate.

In the selective single crystal thin film growth method according to the present invention, a first silicon oxide film, a first silicon nitride film, a second silicon oxide film, and a second silicon nitride film are sequentially coated on a semiconductor substrate, and the formed silicon films are removed to a predetermined width. An opening for exposing the semiconductor substrate is formed, the second silicon oxide film is removed to a greater width than the other silicon film, and the sidewall of the opening is formed to have a recess, and then a single crystal thin film is formed on the exposed semiconductor substrate. A silicon oxide film was formed on the surface of the single crystal thin film, the second silicon nitride film was removed, the exposed side surface of the single crystal thin film was removed, and the side surface was thermally oxidized to form a sidewall thermal silicon oxide film. A thin film is formed, and the surface is planarized by removing the silicon oxide film on the single crystal thin film and the semiconductor thin film on the second silicon oxide film.

Description

Selective single crystal thin film growth method without crystal defect and slope

The present invention relates to a selective single crystal growth method, and more particularly, to a method for forming a single crystal thin film free of crystal defects and slopes at an interface between a single crystal thin film and a silicon oxide film to be formed.

The selective single crystal growth method has been proved experimentally by Endo et al., Which is designed to increase the density of integrated circuits (see Endo et al., Novel Device Isolation Technology with Selective Epitaxial Growth, IEEE Trans.Elect. Devices, vol. ED-31, No. 9, pp. 1283-1288, 1984). However, in this single crystal thin film growth process, a large amount of stacking fault occurs at the interface between the insulating film on the side and the growing semiconductor thin film, so that the reverse junction leakage current increases when the diode is fabricated. The problem was that the characteristics of the device were deteriorated.

In addition, although there is a difference depending on the direction of the pattern, there is a big limitation in that the facet is formed on the side of the single crystal thin film and the flatness is lowered, so that it is applied to the manufacturing process of the device.

1 is a cross-sectional view of a representative prior art disclosed in US Patent No. 4,758,531 to KD Beyer et al. Of IBM in 1988, wherein a selective single crystal is removed from an interface between an insulating film on a side surface and a growing semiconductor thin film. A thin film growth process is shown.

In Fig. 1, reference numeral 1 denotes a semiconductor substrate, 2 denotes a first insulating film on the semiconductor substrate 1, 3 denotes a single crystal thin film, and 4 denotes a thermal silicon oxide film.

In order to perform the selective single crystal thin film growth method of the structure shown in FIG. 1, after coating the first insulating film 2 on the semiconductor substrate 1, the pattern is selectively patterned to expose a predetermined region of the semiconductor substrate 1. To form an opening. Subsequently, a thin second insulating film (not shown) is applied to the entire surface of the substrate 1 and the first insulating film 2, and then anisotropically etched by an etch back process to form sidewall films (not shown) on the side surfaces of the openings. At the same time, all of the second insulating film on the upper surface is removed. Subsequently, the single crystal thin film 3 is grown by an epitaxial process so that the semiconductor substrate 1 exposed through the opening becomes a nucleation site for nucleation upon selective single crystal growth. At this time, crystal defects occur at the interface between the second insulating film and the grown single crystal thin film 3. Next, the second insulating film formed as a sidewall film between the first insulating film 2 and the single crystal thin film 3 is selectively removed, and the label surface and the side surface of the single crystal thin film 3 are separated by high temperature oxygen (O ₂ ). By thermal oxidation in the atmosphere, a thermal silicon oxide film 4 is formed on the trademark surface and side surfaces of the single crystal thin film 3 to remove crystal defects in the side region of the single crystal thin film 3. Thereafter, the thermal silicon oxide film (not shown) formed on the trademark surface of the single crystal thin film 3 is etched back or polished to remove the single crystal growth process.

According to the above-described conventional single crystal growth method, the fact that the crystal defect region formed on the side of the single crystal thin film 3 and the width of the facet formed at the same time is formed to have a width similar to the thickness of the grown single crystal thin film. (Ishitani et al., Silicon Epitaxial Growth and Electrical Properties of Epi / Sidewall Interfaces, Jap. J. Appl. Phys., Part 1, May, pp. 841-848, 1989).

Therefore, in the above prior art, in order to remove the crystal defects formed on the side surfaces of the single crystal thin film, it is necessary to thermally oxidize the single crystal thin film 3 having a very thick layer, so that the process is difficult to control. On the other hand, during the thermal oxidation of the single crystal thin film 3, since the portion to be thermally oxidized is a curved surface or a plane having a right angle (that is, a plane having two horizontal and vertical directions), this causes severe thermal stress around the thermal silicon oxide film. (thermal stress) is generated and there is a problem that can not eliminate the leakage current in this area.

An object of the present invention for solving the above problems of the prior art is to obtain a single crystal semiconductor thin film having no crystal defects and slopes regardless of the crystallographic orientation of the semiconductor substrate, which is rarely accompanied by thermal stress generation, The present invention provides a method for growing a single crystal thin film.

Another object of the present invention is that even when an insulating film made of a silicon oxide film is etched and lost in a reaction gas such as hydrogen chloride during the growth of the selective single crystal thin film, the pattern size does not change, so that the single crystal thin film can be grown with high reliability. It is to provide a single crystal thin film growth method.

In the single crystal thin film growth method according to the present invention for achieving the above object, after applying the first silicon oxide film, the first silicon nitride film, the second silicon oxide film and the second silicon nitride film on the semiconductor substrate, the second silicon nitride film is predetermined Etching the second silicon oxide film exposed through the second silicon nitride film, but etching the second silicon nitride film to a width wider than the width of the second silicon nitride film, and the first silicon nitride film and the first silicon oxide film. Etching the film to the same width as the second nitride film to form an opening for exposing the semiconductor substrate; forming a single crystal thin film on the semiconductor substrate exposed through the opening; and then thermally oxidizing to form a thermal oxide film on the surface thereof. And removing the second silicon nitride film, and removing side surfaces of the single crystal thin film exposed by removing the second silicon nitride film. A step of exposing the silicon nitride film to a predetermined width; and thermally oxidizing the exposed side surfaces of the single crystal thin film to form a thin sidewall thermal silicon oxide film, applying a semiconductor thin film to the entire surface of the substrate, and then And removing the thermal oxide film to planarize the surface of the substrate.

1 is a cross-sectional view showing a single crystal thin film growth process without a crystal defect produced by the prior art;

2 is a cross-sectional view of a semiconductor device without crystal defects and slopes, which is produced by a selective single crystal thin film growth process according to a preferred embodiment of the present invention;

3A to 3H are cross-sectional views sequentially illustrating a selective single crystal thin film growth process according to a preferred embodiment of the present invention.

<Explanation of symbols for main parts of drawing>

1,11 semiconductor substrate 2: first insulating film

3,16: single crystal thin film 12: first silicon oxide film

4,18,19: thermal silicon oxide film 13: first silicon nitride film

17 slope 14: second silicon oxide film

15: second silicon nitride film 20: semiconductor thin film

Hereinafter, with reference to the accompanying drawings a preferred embodiment of the selective single crystal thin film growth method according to the present invention will be described in detail.

FIG. 2 is a cross-sectional view of a semiconductor device without crystal defects and slopes prepared by a selective single crystal thin film growth process according to a preferred embodiment of the present invention. As shown in FIG. 2, FIG. In the device manufactured according to the present invention, the first silicon oxide film 12, the first silicon nitride film 13, and the second silicon oxide film 14 are sequentially stacked on the semiconductor substrate 11, and then patterned to form the semiconductor substrate 11. And a single crystal thin film 16 having no crystal defects and slopes formed on the exposed semiconductor substrate 11, wherein the first silicon oxide film 12 and the first silicon nitride are patterned. A thin thermal silicon oxide film 19 that forms sidewalls perpendicular to the side of the single crystal thin film 16 in contact with the film 13 is formed, and is formed between the thin thermal oxide film 19 and the second silicon oxide film 14. The semiconductor thin film 20 has a structure formed.

3A to 3H are cross-sectional views sequentially illustrating a selective single crystal thin film growth process according to a preferred embodiment of the present invention, with reference to this will be described in detail the selective single crystal thin film growth process without a crystal defect and no slope according to the present invention.

First, as shown in FIG. 3A, a first silicon oxide film 12, a first silicon nitride film 13, a second silicon oxide film 14, and a second silicon nitride film 15 are formed on a semiconductor substrate 11. Laminated in order to form.

3B, the second silicon nitride film 15 and the second silicon oxide film 14 are sequentially etched in order to form an opening for selectively growing a single crystal thin film. In this case, the second silicon oxide film 14 may be subjected to a wet etching method of isotropic etching after anisotropic etching, or may be etched using only an isotropic etching method. In other words, it is necessary to perform selective side etching under the second silicon nitride film 15 by isotropic etching. The depth of the side etch may be adjusted to be small or large depending on the crystal defects occurring on the sidewalls and the formation width of the slope, wherein the side etch depth of the second silicon oxide film 14 with respect to the second silicon nitride film 15 is 100 nm. It is preferable to keep it at -5000nm.

Next, as shown in FIG. 3C, the first silicon nitride film 13 and the first silicon oxide film 12 are etched to the same width as the second silicon nitride film 15 to expose the semiconductor substrate 1. To form.

At this time, since the second silicon oxide film 14 is etched in a wider width than the other films, the side surface of the opening has a side concave portion in the middle portion.

Next, as shown in FIG. 3D, the semiconductor substrate 11 exposed through the opening is made a nucleation site for nucleation upon single crystal growth, and the single crystal thin film 16 is selectively grown thereon. In this case, since a wide {311} slope 17 generated on the sidewall in the <110> direction may be formed, the etch depth of the side surface may be formed so that the formed slope 17 is hidden under the second silicon nitride film 15. It should be adjusted. On the other hand, an important point in this step is that if the sum of the thicknesses of the first silicon nitride film 13 and the first silicon oxide film 12 is small, there are almost no crystal defects generated at the interface with the selectively grown thin film. The fact is studied. Therefore, during the initial selective single crystal growth, since the first silicon nitride film 13 and the first silicon oxide film 12 become sidewall films, there are no crystal defects on the grown sidewall of the single crystal. In the subsequent growth, the second silicon nitride film 15 and the second silicon oxide film 14 become sidewall films, and in this case, they are usually larger than the thickness of the first silicon nitride film 13 and the first silicon oxide film 12. At this time, crystal defects exist on the grown sidewall of the single crystal.

However, this region is removed in a subsequent process, eventually allowing selective single crystal growth without crystal defects and slopes.

Then, as shown in FIG. 3E, the single crystal thin film 16 exposed by the second silicon nitride film 15 is heat-treated in a high temperature oxygen atmosphere to form a thermal silicon oxide film 18, and the second silicon nitride The membrane 15 is removed. In this way, the single crystal thin film 16 which is not thermally oxidized by being covered with the second silicon oxide film 15 in the concave portion of the side surface of the opening is exposed to the outside and removed. At this time, the exposed single crystal thin film 16 has a slope 17 and is a region in which crystal defects are concentrated, as detailed in FIG. 3D.

Subsequently, as shown in FIG. 3F, the side surfaces of the exposed single crystal thin film 16 are anisotropically etched using the second silicon oxide film 14 and the thermal silicon oxide film 18 as an etch mask to form the single crystal thin film 16. By removing the side surfaces, the crystal defects and the slopes 17 present on the side surfaces are physically removed, and a portion of the first silicon nitride film 13 is exposed. In this case, the first silicon nitride layer 13 may serve as an etch stop layer during anisotropic etching of the single crystal thin film 16, and also act as a mask during thermal oxidation. This process is a core process of the present invention. In the prior art, a method of removing a crystal defect by thermal oxidation of a region in which crystal defects exist and removing a crystal defect by formation of a thermal silicon oxide film provides a large amount of crystal defects. Although the part had to be thermally oxidized and the part being thermally oxidized was a curved or perpendicular surface (ie, a plane having two directions, horizontal and vertical), there was a problem of serious thermal stress generation around the thermal silicon oxide film. In the present invention, the above-mentioned problem can be solved by physically removing the crystal defect region by performing anisotropic etching, and on the other hand, both the crystal defect and the slope can be completely removed regardless of the formation width of the defect region.

Next, as shown in FIG. 3G, a thin sidewall thermal silicon oxide film 19 of 50 nm or less is grown on the sidewall of the single crystal thin film 16 etched and exposed in the above step, and the semiconductor thin film 20 is formed. Apply to the front. In this case, the semiconductor thin film 20 may be formed of a polycrystalline silicon thin film, a silicon oxide film or a silicon nitride film. Unlike the conventional technique of thermally oxidizing a curved surface or a surface having a right angle, the present process grows the thermal silicon oxide film 19 only on the sidewall of the single crystal thin film 16 (that is, in one vertical direction). It has the advantage of minimizing the occurrence of thermal stress.

Finally, as shown in FIG. 3H, the entire surface is planarized by etching back or polishing the thermal silicon oxide film 18 on the semiconductor thin film 20 and the single crystal thin film 16. To complete.

According to the selective single crystal thin film growth method of the present invention described above, since the crystal defects and the slopes present at the interface around the sidewall of the single crystal thin film are physically removed by anisotropic etching, the crystal defects are independent of the crystal direction of the semiconductor substrate. A single crystal thin film can be obtained without a slope, and since a thin thermal silicon oxide film having a thickness of 50 nm or less is grown only in the vertical direction, there is an advantage that thermal stress generation is hardly accompanied.

In addition, since the widths of the crystal defect regions and the slopes depend on the growth thickness of the single crystal thin film, in the present invention, the crystal defects and the slopes are adjusted by controlling the thickness of the second silicon oxide film with respect to the second silicon nitride film. It can be removed effectively.

Further, according to the present invention, even if the second silicon oxide film on the side is etched and lost by a reaction gas such as hydrogen chloride, the pattern size is determined by the second silicon nitride film which is not affected by the reaction gas, so that the size of the pattern Does not change, the single crystal thin film can be grown with high reliability.

Therefore, the selective single crystal thin film growth method of the present invention can be effectively used in the device isolation process, the collector of the dipole transistor, the MOS device and the like.

Claims (6)

Applying a first silicon oxide film, a first silicon nitride film, a second silicon oxide film, and a second silicon nitride film on a semiconductor substrate, and then etching the second silicon nitride film to a predetermined width; and exposing through the second silicon nitride film. Etching the second silicon oxide film having a width larger than that of the second silicon nitride film; Etching the first silicon nitride film and the first silicon oxide film to the same width as the second nitride film to form an opening exposing the semiconductor substrate; Forming a single crystal thin film on the semiconductor substrate exposed through the opening, followed by thermal oxidation to form a thermal oxide film on the surface thereof; Removing the second silicon nitride film and simultaneously removing side surfaces of the single crystal thin film exposed by removing the second silicon nitride film to expose the first silicon nitride film to a predetermined width; Thermally oxidizing the exposed side surfaces of the single crystal thin film to form a thin sidewall thermal silicon oxide film, applying a semiconductor thin film to the entire surface of the substrate, and then removing the surface portion and the thermal oxide film of the semiconductor thin film to planarize the surface of the substrate. Selective single crystal thin film growth method comprising a. The method of claim 1, And the second silicon oxide film is primarily anisotropically etched and isotropically etched second to laterally etch the lower portion of the second silicon nitride film. The method of claim 2, Selective single crystal thin film growth method, characterized in that the side etching depth of the second silicon nitride film is 100nm to 5000nm. The method of claim 1, And a polycrystalline silicon thin film, a silicon oxide film, or a silicon nitride film instead of the semiconductor thin film. The method of claim 1, And the sidewall thermal silicon oxide film is formed to a thickness of 50nm. The method of claim 1, And the sidewall thermal silicon oxide film is not in contact with the second silicon oxide film.

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