JPS6233415A - Manufacture of single crystal semiconductor film - Google Patents

Abstract

PURPOSE:To make it possible to single-crystallize the polycrystalline or amorphous semiconductor film of large area and high quality located on the first insulating film by a method wherein the single crystal semiconductor film, having the substrate of a longitudinal aperture part as a seed and the equal crystal axis distribution, is formed on the first insulating film while the polycrystalline or amorphous film is being melted successively. CONSTITUTION:When a laser beam 7 having specific power is scanningly applied to a thin oxide film 4 and a longitudinal tungsten film 5 from a longitudinal aperture part to the direction indicated by the arrow in the diagram, a polycrystalline silicon film 3 is melted and a melted part 30 is formed. Using the single crystal silicon substrate 1 of a longitudinal aperture part 6 as a seed, an epitaxial growth wherein the direction of crystal axle of said seed is taken over is generated continuously. As the direction vertical to the scanning direction the the temperature distribution in scanning direction of the melted part and the like of the polycrystalline silicon film 3 can be controlled on a thick oxide film 2 by the longitudinal tungsten film 5, the state of solidification and recrystallization is generated continuously from the solid-to-liquid interface of the melted part of the polycrystalline silicon film 3 on the region located under each longitudinal tungsten film 5 toward the region having no longitudinal tungsten film 5, and the appearance of a crystal grain boundary can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a single crystal semiconductor film, and particularly to a single crystal semiconductor substrate, a thick insulating film formed on the substrate,
A sample consisting of a polycrystalline or amorphous semiconductor film formed on the thick insulating film is scanned while being irradiated with a continuous wave laser beam to melt the semiconductor film and to form a base single crystal semiconductor substrate. The present invention relates to a method of manufacturing a single crystal semiconductor film on the above insulating film as a seed.

[Prior Art] Conventionally, there has been a method shown in FIG. 4 for manufacturing a single crystal semiconductor film on an insulating film. In the figure, 1o is a sample. Single-crystal silicon substrate 1 has a (100) plane as a main surface,
A thick oxide film 2 made of silicon dioxide is formed on this main surface. The thick oxide film 2 has a longitudinal opening 6 extending perpendicularly to the plane of the paper in a part thereof, and the single crystal silicon substrate 1 extends n to the surface of the thick oxide film 2 in this part. A polycrystalline silicon film 3 is formed on the longitudinal opening 6 and on the thick oxide film 2 by chemical vapor deposition (hereinafter referred to as cVD). The polycrystalline silicon film 3 is irradiated with a laser beam 7, whereby the polycrystalline silicon film is J-melted. 7o is a laser irradiation surface of the laser beam 7. A melted portion 30 of the polycrystalline silicon film 3 is formed on the longitudinal opening 6 and on the thick oxide film 2 by the laser beam 7 . Further, on the thick oxide film 2, a silicon bulge 31 is formed in which the molten portion 3o traces the plane direction of the single crystal silicon substrate 1 and is made into a single crystal. Laser light 7 scans the upper surface of polycrystalline silicon film 3 in the direction of arrow 8 .

Therefore, when manufacturing a semiconductor single crystal film on the thick oxide film 2, the polycrystalline silicon film 3 on the longitudinal opening 6 and on the thick oxide film 2 is melted by irradiation with the laser beam 7, and this melting is further prevented. Single crystal silicon substrate 1 with longitudinal opening 6
By extending Q to the surface of the polycrystalline silicon film 3, the epitaxial growth of the single crystal silicon substrate 1 in the longitudinal opening 6 is disrupted during solidification, and the polycrystalline silicon film 3 becomes single crystal. Therefore, when the polycrystalline silicon film 3 is scanned in the direction of the arrow 8 while being irradiated with the laser beam 7, the polycrystalline silicon pattern 3 is melted to form a melted part 30, and epitaxial growth continues from this melted part in the scanning direction. A single crystal film can be grown even on the thick oxide film 2 as an insulating film.

[Problems to be Solved by the Invention] However, in such a conventional method for manufacturing a single crystal semiconductor film, the polycrystalline silicon film 3 melted by the laser beam 7
When the molten part 30 moves away from the longitudinal opening 6, the flow of heat from the thick oxide film 2 to the single crystal silicon substrate 1 becomes dominant, and solidification and recrystallization no longer occur continuously from the opening 6. Therefore, there was a problem in that the epitaxial single crystal from the elongated opening 6 grew only about 100 to 200 μm.

Further, since the heat distribution in the lateral direction perpendicular to the scanning direction of the laser beam 7 is not controlled, even small fluctuations in the power distribution of the laser beam 7 may stop epitaxial single crystal growth. To further explain this mechanism with reference to FIGS. 5(A) and 5(B), the power distribution of the laser beam 7 is
As shown in Figure (A), it usually has a normal distribution or a shape close to it.
When I 3 is melted and crystallized 11, the temperature distribution within the polycrystalline silicon film 3 and its r8M portion 30 becomes a distribution similar to the power distribution of the laser beam 7 shown in FIG. 5 (Δ).

Therefore, polycrystalline silicon l! by laser beam 7! J3
The solid-liquid interface 9 moves as shown by the dotted line in FIG. Since the scanning direction passes through the center of the laser irradiation surface 70,
There was a problem in that grain boundaries appeared and single crystallization was not possible.

This invention was made to solve the above-mentioned problems, and its purpose is to provide a method for manufacturing a single-crystal semiconductor film that enables formation of a large-area, high-quality single crystal on an insulating film. do.

[Means for Solving the Problems] The vJib method for a single crystal semiconductor film according to the present invention includes a single crystal semiconductor substrate and a longitudinal opening formed on the substrate through which the substrate is exposed at least in part. 1st
In a sample composed of an insulating film and a polycrystalline or amorphous semiconductor +1Q formed on the substrate d3 and the longitudinal opening, a second W is formed on the polycrystalline or amorphous semiconductor film.
A edge film is formed, and a plurality of longitudinal reflective films are formed on the second insulating panel at intervals and in a direction intersecting the longitudinal opening. The reflective film is scanned while being irradiated in the longitudinal direction of the longitudinal reflective film from the longitudinal opening, thereby sequentially melting the polycrystalline or amorphous semiconductor layer while the substrate in the longitudinal opening is heated. A single crystal semiconductor film with the same crystal axis direction as a seed is v81
This is a method of forming on top of insulation.

[Function] In this invention, when scanning a sample while irradiating it with light from a light source, the light from the light source is reflected by the longitudinal reflective film, and the polycrystalline or amorphous semiconductor in the region under the longitudinal wiping film fJ31jJ is The temperature of the melted part of the film is kept lower than the temperature of the melted part of the polycrystalline or amorphous semiconductor film in the area without the longitudinal reflective film, so that solidification and recrystallization are less likely to occur under the longitudinal reflective film. This occurs continuously from the area to the area where there is no longitudinal reflective film. The second insulating film also prevents atoms of the longitudinal reflective film from being squeezed into the polycrystalline or amorphous semiconductor film as impurities during melting and recrystallization of the polycrystalline or amorphous semiconductor film. prevent.

*Example] Embodiments of the present invention will be described below with reference to the drawings.

In the description of this embodiment, the description of parts that overlap with the description of the conventional technology will be omitted as appropriate.

1, 2, and 3 are plan views for explaining a method for manufacturing a single crystal semiconductor film that is an example of the present invention, and A-AI in FIG. FIG. 1 is a partially enlarged cross-sectional view, and a partially enlarged cross-sectional view taken along line 8-Ba in FIG. This example is the same as the conventional method for manufacturing a single crystal semiconductor film except for the following points. That is, on the polycrystalline silicon 1113 of the sample 10, a thin oxide 1114 with a film thickness of about 500 Å is formed by the CVD method. Also, on the oxidized oxide M4, the eldest of the longitudinal openings 6 are spaced apart from each other. A plurality of longitudinal tungsten films 5 having a film thickness of approximately 3000λ are formed by CVD in a direction substantially perpendicular to the direction, and the longitudinal end of each longitudinal tungsten film 5 is formed into a longitudinal anti-whitening portion 6. They are separated from each other by the upper width. 70 is a laser irradiation surface of the continuous wave laser beam 7, and this laser irradiation surface includes a plurality of long-grain tungsten s5.

Thus, the thin oxide film 4 and the elongated tungsten film 5 are removed from the elongated opening 6 by the laser beam 7 with a constant power.
When scanning while irradiating in the direction, polycrystalline silicon II
3 is melted to form a molten part 30, and from this molten part epitaxial growth occurs continuously in the direction of the crystal axis using the single crystal silicon substrate 1 of the longitudinal opening 6 as a seed, and this epitaxial growth is performed using a laser beam. As the light 7 scans in the direction of the arrow 8, it travels over the thick oxide 112 in that direction. At this time, since the elongated tungsten film 5 acts as a reflective film for the laser beam 7, the temperature of the melted portion of the am polycrystalline silicon lI3 under each elongated tungsten j115 is lower than that of gAil! without the elongated tungsten l15. The concentration is kept lower than that of the melted portion of polycrystalline silicon group 3, and since the elongated tungsten film 5 has high thermal conductivity,
Heat flow occurs through this elongated tungsten film in its longitudinal direction towards the elongated opening 6. In this way, elongated tungsten 1! Thicker oxidation by II5! ! Since the temperature distribution in the direction perpendicular to the scanning direction and in the scanning direction of the melted portion of the polycrystalline silicon group 3 is controlled on the polycrystalline silicon s3 in the region under each longitudinal tungsten film 5, solidification and recrystallization This occurs continuously from the solid-liquid interface of the molten part toward the region where there is no elongated tungsten film 5, and the appearance of grain boundaries is suppressed. Further, as the laser beam 7 scans, the solid-liquid interface of the molten portion of the polycrystalline silicon group 3 moves in the scanning direction as a whole, so that epitaxial growth progresses on the thick oxide 12. Further, the thin oxide M4 prevents atoms of the elongated tungsten 115 from being mixed as impurities into the single-crystal silicon film when the polycrystalline silicon film 3 is melted and recrystallized. In this way, a high-quality single-crystal silicon film epitaxially inherited from the single-crystal silicon substrate 1 of the elongated entrance portion 6 in its crystal axis direction can be formed over a large area on the thick oxide 112.

In addition, in the above embodiment, a case was shown in which a tungsten film was used as a reflection film for laser light, but anti-G'1ll
1 reflects the laser beam and the melting point of silicon (1
The material does not matter as long as the metal film has a melting point higher than 420°C (420°C); for example, molybdenum film, titanium film, or a silicide film of these high-melting-point metals may be used, and the above-mentioned method may also be used in these cases. Qin effect similar to the example.

Furthermore, in the above embodiment, a case where a thin oxide film is provided between the polycrystalline silicon film and the reflective film is shown, but as a model in which a thin oxide film is provided between the polycrystalline silicon film and the reflective film, it is possible to provide a thin oxide film between the polycrystalline silicon film and the reflective film. During melt recrystallization, atoms in the reflective film become 74I.
Any film may be used as long as it can prevent the incorporation of impurities into the Fa crystallized silicon film; for example, a silicon nitride film may be provided, and in this case, the same effect as in the above embodiment can be achieved.

In addition, although the above example shows the case where a polycrystalline silicon film on a thick oxide film is made into a single crystal, the method for making a polycrystalline silicon film on a thick oxide film into a single crystal is also applicable to other polycrystalline semiconductor films or amorphous semiconductor films. Also in these cases, the same effects as in the above embodiments can be achieved.

Further, in the above embodiment, the case where the polycrystalline silicon film is formed on the silicon dioxide film is shown, but the polycrystalline silicon film may be formed on another insulating film.
In this case as well, the same effects as in the above embodiment can be achieved.

[Effects of the Invention] As described above, according to the present invention, a single crystal semiconductor substrate,
a first insulating film formed on the substrate and having a longitudinal opening through which the substrate is exposed in at least a portion thereof; and a polycrystalline or amorphous semiconductor film formed on the substrate and the longitudinal opening. In the sample configured, a second insulating film is formed on a polycrystalline or amorphous semiconductor film, and a plurality of longitudinal reflections are formed on the second insulating film at intervals and in a direction intersecting the longitudinal opening. A film is formed and the second layer is exposed to light from the light source.
The insulating film and the longitudinal reflective film are scanned while being irradiated from the longitudinal opening in the longitudinal direction of the longitudinal reflective film, thereby sequentially melting the polycrystalline or amorphous semiconductor film.
Since a single crystal semiconductor film with the same crystal axis direction is formed on the first insulating film using the substrate having the longitudinal opening as a seed, the polycrystalline or amorphous semiconductor film can be melted on the first insulating film. In the scanning direction of the section! ! ! The concentration distribution in the vertical direction and the scanning direction can be controlled. Therefore, epitaxial growth from the longitudinal opening can be easily performed, and the polycrystalline or amorphous semiconductor film on the first insulating film can be grown over a large area. And it can be made into a single crystal with high quality.

[Brief explanation of the drawing]

1, 2, and 3 are a plan view for explaining a method for manufacturing a single crystal semiconductor film according to an embodiment of the present invention, a partial enlarged sectional view taken along line A-A1 in FIG. 1, and FIG. 8 in Figure 1
-B is a partially enlarged sectional view. FIG. 4 is a cross-sectional view for explaining a conventional method for manufacturing a single crystal semiconductor film. 5A and 5B are diagrams showing the power distribution of laser light and the state of single crystallization of a polycrystalline silicon film in the method for manufacturing a single crystal semiconductor film. In the figures, 1 is a single crystal silicon substrate. , 2 is a thick oxide film, 3 is a polycrystalline silicon film, 30 is a melted part, 31 is a single crystal silicon film, 4 is a thin oxide film, 5 is a longitudinal tungsten film, 6 is a longitudinal opening, 7 is the laser beam, 10 is the sample, and 70 is the laser irradiation surface. In each figure, the same reference numerals indicate the same or corresponding parts. Agent Yusuke Oiwa Figures 4 and 5

Claims (4)

[Claims] (1) A method of scanning a sample while irradiating it with light from a light source to single-crystallize a polycrystalline or amorphous semiconductor film contained in the sample, the sample comprising: a single-crystal semiconductor substrate; a first insulating film formed on the substrate and having a longitudinal opening through which the substrate is exposed in at least a portion thereof; and the polycrystalline or amorphous semiconductor formed on the substrate and the longitudinal opening. forming a second insulating film on the polycrystalline or amorphous semiconductor film; forming a plurality of longitudinal reflective films; scanning the second insulating film and the longitudinal reflective film with light from the light source while irradiating the longitudinal reflective films from the longitudinal openings; By this, while sequentially melting the polycrystalline or amorphous semiconductor film, a single crystal semiconductor film having the same crystal axis direction is formed on the first insulating film using the substrate in the longitudinal opening as a seed. A method for manufacturing a single crystal semiconductor film, comprising the steps of: (2) The method for manufacturing a single crystal semiconductor film according to claim 1, wherein the light source is an argon laser. (3) The single crystal semiconductor substrate is a silicon substrate, the first insulating film is a silicon dioxide film, and the second insulating film is a silicon nitride film, a silicon oxide film, or a silicon nitride film and a silicon oxide film. 2. A method for producing a single crystal semiconductor film according to claim 1, which is a double film of a single crystal semiconductor film. (4) The method for manufacturing a single crystal semiconductor film according to claim 1, wherein the longitudinal reflective film is a high melting point metal film or a high melting point metal silicide film.