JPH0795525B2 - 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 for 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 a laser beam is applied to this non-single-crystal thin film. 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 the like or irradiating an energy beam such as heating with a lamp or heater to melt and recrystallize. .

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 a method of eliminating the step by embedding the seed portion in advance with the same material as the thin film 23 desired to be single crystallized, but if the difference in thermal conductivity between the thin film 23 desired to be single crystalized and the interlayer insulating films 22 and 27 is large, the seed portion The temperature difference between the above and 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.
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 26 around the exposed portion 26a of the single crystal thin film 26 is used in this method.
Also melts, and then solidifies at random, causing nucleation at random, and trying to use the single crystal thin film 26 with controlled crystal orientation as a seed, but the problem that only a thin film with random crystal orientation can be obtained was there.

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 and 21b are exposed portions of a single crystal substrate, 22 and 27 are non-single crystal insulating films, 23 and 28 are non-single crystal thin films to be single crystallized, 24 and 29 are surface protective films, and 25 and 30 are laser beams. Or irradiation with an energy beam such as electron beam irradiation or heating with a lamp or heater, 26 and 31 are single crystallized thin films, and 26a is an exposed portion of the single crystallized thin film.

The present invention has been devised in view of the above points, and stably obtains two or more single crystal thin films that match the crystal orientation of a substrate on a non-single crystal insulating film that covers the single crystal substrate. It is an object of the present invention to provide a method for producing a single crystal thin film that enables

<Means for Solving the Problems> In order to achieve the above-mentioned object, the present invention melts a non-single-crystal thin film formed on a single-crystal substrate covered with a non-single-crystal insulating film by energy beam irradiation. By recrystallizing, a single crystal thin film whose crystal orientation matches that of the single crystal substrate is obtained.
In the method of manufacturing a single crystal thin film to be formed in more than one layer, it is desired to single crystallize a single crystal thin film that is already under the non-single crystal thin film that is to be single crystallized and has a crystallographic orientation that matches that of the single crystal substrate. A method for controlling the crystal orientation of a non-single-crystal thin film, wherein the seed single-crystal thin film is patterned so that the seed single-crystal thin film further has a region in direct contact with a lower single-crystal thin film or a single-crystal substrate. Together with the non-single-crystal thin film to be single-crystallized, when the region in direct contact with the seed single-crystal thin film is melted by energy beam irradiation, the single-crystal thin film as the seed is a lower single-crystal substrate or a single-crystal thin film. The method for producing a single crystal thin film is characterized in that the region in direct contact is also melted at the same time.

<Operation> In a method in which a single crystal thin film formed so that the crystal orientation is the same as that of the single crystal substrate is used as a seed, when the single crystal thin film is patterned, the single crystal thin film is a lower single crystal thin film or a single crystal thin film. By leaving the region that is in direct contact with the crystal substrate, when the thin film that you want to single crystallize is melted by irradiation with an energy beam, the thin film you want to single crystallize up to the periphery of the region that directly contacts the lower single crystal thin film that is the seed. Even if the single crystal thin film melts, if the thermal conductivity of the single crystal thin film is higher than the thermal conductivity of the interlayer insulating film, the region where this single crystal thin film is in direct contact with the lower single crystal thin film or single crystal substrate Since heat easily escapes from the bottom layer to the lower layer, solidification starts from that portion, and it becomes possible to form a single crystal thin film having the same crystal orientation as that of the single crystal substrate even in two or more layers without random nucleation.

When the region of the thin film to be further monocrystallized that is in direct contact with the single crystal thin film, which is the seed of the lower layer formed so that the crystal orientation matches that of the single crystal substrate, is melted by energy beam irradiation, this single crystal thin film If the position where the single crystal substrate or the region in direct contact with the single crystal thin film is also melted at the same time is set, the seed single crystal thin film is further lower because of the difference in thermal conductivity between the single crystal thin film and the interlayer insulating film. Since solidification always begins in the region directly in contact with the single crystal substrate or the single crystal thin film, more random nucleation can be prevented, and a single crystal thin film having the same crystal orientation as the single crystal substrate can be stably formed even in two or more layers. Like

<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 the entire surface of the SiO ₂ film 4 is etched, FIG.
The single crystal silicon film 6 is exposed on the exposed portion 1a of the substrate 1 as shown in FIG.
Patterning is performed by a normal photolithography method so as to include a region which is in direct contact with, and a single crystal silicon film 61 as a seed is formed. The size of this kind of single crystal silicon film 61 is 20 μm square.

Next, S is formed on the single crystal silicon film 61 by the atmospheric pressure CVD method.
An iO ₂ film 7 having a thickness of 2 μm is formed, and only a portion where the single crystal silicon film 61 is to be exposed is patterned by a normal photolithography method to form a 2 μm square opening 6a. At this time, the distance between the exposed portion 1a of the single crystal silicon substrate 1 and the exposed portion 6a of the single crystal silicon film 61 is 5 μm.

Next, a polycrystalline silicon film 8 is formed on this by a low pressure CVD method.
0.5 μm thick, and 0.26 SiO ₂ film 9 by atmospheric pressure CVD method.
After the formation of μm, as shown in FIG. 1 (e), the single crystal silicon film 61 is formed on the single crystal silicon substrate 61 at a scanning speed of 100 mm / sec with an argon laser beam 10 having a melting width of 60 μm and a laser power of 8 W. Scanning is performed from a region directly contacting the exposed portion 1a, and the molten portion 11 is solidified in the direction of arrow 13. That is, first, using the substrate 1 as a seed, the melted portion 11 of the single crystal silicon film 61 is made into single crystal silicon whose crystal orientation is the same as that of the single crystal silicon substrate 1, and then using this portion as a seed, the polycrystalline silicon film 8 is made into a single crystal. A single crystal silicon film 12 having the same crystal orientation as that of the single crystal silicon substrate 1 is obtained. At this time, the melting width of the single crystal silicon film 61 is 30 μm, and the fact that the single crystal silicon substrate 1a has been melted means that the single crystal silicon film 61 is melted.
A sample using a polycrystalline silicon film in place of 61 was separately confirmed.

<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 also obtained from the single crystal substrate. In the case of a stable single crystal substrate, there is no influence of a large step as in the case of the above, and there is no random nucleation such as using a single crystal thin film already formed so that the crystal orientation matches that of the single crystal substrate. A single crystal thin film having the same crystal orientation can be formed.

[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, 2,4,7,9 …… SiO ₂ film, 3,8 …… polycrystalline silicon film, 5,10 …… argon laser beam Irradiation, 6,12 …… Single crystal silicon film, 61 …… Patterned single crystal silicon film as seed, 6a …… Exposed part of single crystal silicon film as seed, 11 …… Fused region, 13 …… Solidification direction.

Claims (5)

[Claims] 1. A non-single-crystal thin film formed on a single-crystal substrate coated with a non-single-crystal insulating film is melted and recrystallized by irradiation with an energy beam to obtain a single crystal whose crystal orientation matches that of the single-crystal substrate. In a method for producing a single crystal thin film in which two or more crystal thin films are formed through a non-single crystal insulating film, the crystal orientation is the same as that of the single crystal substrate, which is located below the non-single crystal thin film to be single crystallized. A method for controlling the crystal orientation of a non-single-crystal thin film that is desired to be single-crystallized using the prepared single-crystal thin film as a seed, wherein the single-crystal thin film as a seed further has a region in direct contact with the lower-layer single-crystal thin film or single-crystal substrate. While patterning the single crystal thin film as the seed as described above, when the region where the non-single crystal thin film to be single crystal is in direct contact with the single crystal thin film as the seed is melted by energy beam irradiation, the seed Method for producing a single crystal thin film characterized by single crystal thin film has no such melt further underlying single crystal thin film to a region in contact monocrystalline substrate directly at the same time. 2. The single crystal thin film according to claim 1, wherein the thermal conductivity of the non-single crystal thin film to be single crystallized is higher than the thermal conductivity of the non-single crystal insulating film. Production method. 3. The energy beam irradiation is performed by scanning an energy beam over a non-single-crystal thin film to be single-crystallized, and the seed single-crystal thin film is in direct contact with a lower single-crystal thin film or a single-crystal substrate. 3. The region according to claim 1, wherein the region is in front of the region in which the non-single-crystal thin film to be single-crystallized is in direct contact with the seeding single-crystal thin film in the energy beam scanning direction. Method for manufacturing single crystal thin film of. 4. The method for producing a single crystal thin film according to claim 1, wherein the single crystal substrate is silicon. 5. 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.