JPH0795526B2 - Method for manufacturing single crystal thin film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a single crystal thin film, and more specifically to a non-single crystal thin film such as an amorphous or polycrystalline film formed on a non-single crystal insulating film. The present invention relates to an improvement in a method of single-crystallizing a non-single-crystal thin film by irradiating a laser beam, an electron beam, or the like or an energy beam such as heating with a lamp or a heater.

<Prior Art> Conventionally, a non-single-crystal thin film such as an amorphous or polycrystalline film is formed on an insulating film having a partial opening formed on a single-crystal substrate, and the non-single-crystal thin film is subjected to laser irradiation. A method has been proposed for producing a single crystal thin film whose crystal orientation matches that of a single crystal substrate by irradiating an electron beam or electron beam or by irradiating an energy beam such as heating with a lamp or heater to melt and recrystallize. There is.

This conventionally proposed method is generally shown in FIG.
And as shown in (b), a partial opening 21 is formed on the single crystal substrate 21.
After forming an insulating film 22 having a and further forming an amorphous or polycrystalline non-single-crystal thin film 23 and a surface protective film 24 to be single-crystallized thereon, irradiation with a laser beam, an electron beam or the like or a lamp. By performing energy beam irradiation 25 such as heating with a heater from the region where the non-single crystal thin film 23 is in direct contact with the exposed portion 21a of the single crystal substrate 21, the non-single crystal thin film is used as a seed for crystal growth. 23 is single-crystallized to form a single-crystal thin film 26 whose crystal orientation matches that of the single-crystal substrate 21.

When forming two or more single crystal thin films,
As shown in FIGS. 3 (a) and 3 (b), the single crystal substrate 21 is used as a direct seed, or as shown in FIGS. 4 (a) to 4 (e), the crystal orientation is the same as that of the single crystal substrate 21. There is a method of using the single crystal thin film 26 thus formed as a seed. 3 single crystal thin films
The same applies when forming more than one layer.

<Problems to be Solved by the Invention> However, in the method of forming two or more single crystal thin films using the single crystal substrate 21 shown in FIG. 3 as a seed, the seed portion (single crystal substrate 21
Since the step difference at the exposed portion 21b) of the above becomes large, it is difficult to control the crystal orientation satisfactorily. There is also a method of eliminating the step by embedding the seed portion in advance with the same material as the thin film 23 to be single-crystallized, but if the difference in thermal conductivity between the thin film 23 to be single-crystallized and the interlayer insulating films 22 and 27 is large, the seed portion Then, the temperature difference in other areas becomes too large, and the thin film 23 to be single-crystallized in both parts cannot be melted well without an unmelted part or scattering.

In order to avoid this problem, the lower single crystal thin film 26 formed so that the crystal orientation is the same as that of the single crystal substrate 21 shown in FIG.
There is a method of using the patterned thin film 29 of
In this method, when the thin film 28 to be single-crystallized by energy beam irradiation is melted and recrystallized, the single-crystal thin film 29 around the exposed portion 29a of the single-crystal thin film 29 is also melted. When this molten region is used as a seed for the single crystal thin film 29 by controlling the crystal orientation over the entire area of the patterned single crystal thin film 29, only a thin film having a random crystal orientation can be obtained. There was a problem.

In FIGS. 4 (a) to 4 (e), the same parts as those in FIGS. 2 (a) and (b) and FIGS. 3 (a) and (b) are denoted by the same reference numerals, and 21 is a single crystal. Substrate, 21a is an exposed portion of the single crystal substrate 21, 22 and 27 are non-single crystal thin films, 23 and 28 are non-single crystal thin films to be single-crystallized, 24 and 30 are surface protective films,
25 and 31 are irradiation with an energy beam such as irradiation with a laser beam or an electron beam or heating with a lamp or a heater, 26 and 33 are single crystallized thin films, 29 is a single crystal thin film as a patterned seed, and 29a is a seed. The exposed portion of the single crystal thin film 29, and 32 are molten regions.

The present invention was devised in view of the above points, and it is possible to stably obtain two or more single crystal thin films that match the crystal orientation of the substrate on the non-single crystal thin film that covers the single crystal substrate. An object of the present invention is to provide a method for manufacturing a single crystal thin film.

<Means for Solving Problems> In order to achieve the above-mentioned object, the present invention is a non-single-crystal thin film formed on a single-crystal substrate coated with a non-single-crystal thin film is melted and recrystallized by energy beam irradiation. By converting
In a method of forming two or more single crystal thin films having crystal orientations identical to those of a single crystal substrate, a single crystal thin film which is located below a non-single crystal thin film desired to be made into a single crystal and whose crystal orientation is already identical to that of the single crystal substrate. A method for controlling the crystal orientation of a non-single-crystal thin film to be single-crystallized using a crystalline thin film as a seed, wherein a single crystal of a lower layer formed so that the crystallographic orientation matches the single-crystal substrate of the non-single-crystal thin film to be single-crystallized. The area directly contacting the crystal thin film is irradiated with the energy beam as described above, and by patterning the pattern of the single crystal thin film as a seed larger than the melting area that melts the contacting area and the surrounding single crystal thin film, a single crystal substrate is obtained. It is constructed so as to obtain a single crystal thin film having the same crystal orientation.

<Operation> In the method using a single crystal thin film formed so that the crystal orientation matches the crystal orientation of the single crystal substrate, the non-single crystal thin film desired to be single crystal is formed so that the crystal orientation matches the crystal orientation of the single crystal substrate. When the region directly contacting the lower single crystal thin film is melted by the energy beam irradiation, the contact region and the single crystal thin film around it are also melted. When the melted region of the single crystal thin film to be the seed is spread over the entire patterned single crystal thin film, there is no seed for controlling the crystal orientation at the time of the next solidification, so that the crystal orientation cannot be controlled. On the other hand, as in the present invention, the melting region of the single crystal thin film to be used as a seed is made smaller than the pattern of this single crystal thin film, so that the region where the crystal orientation coincides with that of the substrate always remains. Since the crystal is grown by using as a seed, it becomes possible to stably form a single crystal thin film having the same crystal orientation as that of the single crystal substrate even in two or more layers.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

1 (a) to 1 (f) are process diagrams for explaining one embodiment of the present invention.

First, as shown in FIG. 1A, a SiO ₂ film 2 having a thickness of 2 μm is formed on a single crystal silicon substrate 1 by an atmospheric pressure CVD method, and only a portion where the single crystal silicon substrate 1 is to be exposed is formed by a normal photolithography method. Patterning is performed to form a 2 μm square opening 1a. Next, the polycrystalline silicon film 3 is formed by the low pressure CVD method.
0.5 μm thick, and 0.26 SiO ₂ film 4 by atmospheric pressure CVD method.
After the formation of μm, the melting width is 60μ as shown in Fig. 1 (b).
An argon laser beam 5 having a laser power of 10 W and a scanning speed of 100 mm / sec was scanned from a region where the polycrystalline silicon film 3 was in direct contact with the exposed portion 1a of the single crystal silicon substrate 1, and the exposed portion 1a of the substrate 1 was seeded. As a result, the polycrystalline silicon film 3 is monocrystallized to obtain a single crystal silicon film 6 whose crystal orientation matches that of the single crystal silicon substrate 1.

Next, after etching the entire surface of the SiO ₂ film 4, as shown in FIG. 1C, the single crystal silicon film 6 is patterned by a normal photolithography method to form a single crystal silicon film 7 as a seed. The size of the single crystal silicon film 7 of this kind is 50 μm square. Next, a SiO ₂ film 8 having a thickness of 2 μm is formed thereon by an atmospheric pressure CVD method, and only a portion where the single crystal silicon film 7 as a seed is to be exposed is patterned by a normal photolithography method to form a 2 μm square opening 7a. Form.

Then, as shown in FIG. 1 (d), a polycrystalline silicon film 9 is formed to a thickness of 0.5 μm by a low pressure CVD method, and a SiO ₂ film 10 is formed to a thickness of 0.26 μm by an atmospheric pressure CVD method. ), The melting width of polycrystalline silicon 9 is 60μm, laser power is 8W.
Argon laser beam 12 is scanned at a scanning speed of 100 mm / sec from a region of the polycrystalline silicon film 9 that is in direct contact with the exposed portion of the single crystal silicon film 7 as a seed, and the single crystal silicon film 7 is used as a seed. 9 is single-crystallized to obtain a single-crystal silicon film 13 whose crystal orientation matches that of the single-crystal silicon substrate 1. At this time, the melting width of the single crystal silicon film 7 as a seed is
It was separately confirmed in a sample using a polycrystalline silicon film instead of the single crystal silicon film 7 that the entire region of the seed single crystal silicon film 7 was not melted at 30 μm.

<Effects of the Invention> As described above, according to the present invention, when forming two or more single crystal thin films having the same crystal orientation as that of the single crystal substrate, the seeds of the second or more thin films are formed from the single crystal substrate. There is no effect of a large step as in the case of, and the entire region of the single crystal thin film as a seed is melted when the upper-layer polycrystalline silicon is irradiated with an energy beam, and random nucleation does not occur, Since the crystal is always grown using the unmelted region of the single crystal thin film as a seed, it is possible to stably form a single crystal thin film having a crystal orientation that matches that of the single crystal substrate.

[Brief description of drawings]

1 (a) to 1 (f) are process charts showing sample cross sections for explaining one embodiment of the present invention, and FIG. 2 (a).
And (b) are process diagrams showing sample cross sections for explaining a method for controlling the crystal orientation of a single-layer thin film using a single crystal substrate as a seed, and FIGS. 3 (a) and 3 (b) and FIG. 4 ( 6A to 6E are process diagrams showing sample cross sections for explaining a conventional method for controlling the crystal orientation of a thin film having two or more layers. 1 …… single crystal silicon substrate, 1a …… exposed part of single crystal silicon substrate, 2,4,8,10 …… SiO ₂ film, 3,9 …… polycrystalline silicon film, 5,12 …… argon laser beam Irradiation, 6,13 ……
Single crystal silicon film, 7 ... Seed single crystal silicon film,
7a: exposed portion of the single crystal silicon film used as a seed, 11: molten region.

Claims (3)

[Claims] 1. A non-single crystal thin film formed on a non-single-crystal insulating film-coated non-single-crystal thin film is melted and recrystallized by energy beam irradiation to obtain a single crystal whose crystal orientation matches that of the single-crystal substrate. In a method of forming two or more thin films, a non-single-crystal thin film that is formed below the non-single-crystal thin film that is to be single-crystallized and that has already been formed so that its crystal orientation matches that of the single-crystal substrate is used as a seed. A method for controlling the crystal orientation of a crystal thin film, wherein the region of the non-single-crystal thin film to be single-crystallized that directly contacts the lower single-crystal thin film formed so that the crystal orientation matches that of the single-crystal substrate The pattern of the seed single crystal thin film is made larger than that of the melted region where the contacting region and the surrounding single crystal thin film are melted by irradiation. The magnitude of the substantially 50μm square, the thickness of the non-single-crystal thin film formed thereon is approximately 2μm thick, the size of the opening formed in the non-single-crystal insulating film substantially 2μ
A method for manufacturing a single crystal thin film, characterized in that it is m square, the thickness of the non-single crystal thin film to be recrystallized is approximately 0.5 μm, and the power of the energy beam to be irradiated is approximately 8 W. 2. The method for producing a single crystal thin film according to claim 1, wherein the single crystal substrate is silicon. 3. The method for producing a single crystal thin film according to claim 1, wherein the non-single crystal thin film to be single crystallized is silicon.