JPH01721A - Manufacturing method of single crystal thin film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for manufacturing a single crystal thin film, and more particularly, to a method for manufacturing a single crystal thin film such as an amorphous or polycrystalline thin film formed on a non-single crystal insulating film. The present invention relates to an improvement in a method for converting a non-single crystal thin film into a single crystal by applying energy beam irradiation such as laser beam or electron beam irradiation or heating with a lamp, heater, etc.

<Conventional technology> Conventionally, a non-single crystal thin film such as amorphous or polycrystalline is formed on an insulating film having a partial opening formed on a single crystal substrate, and a laser is applied to this non-single crystal thin film. Irradiation with beams, electron beams, etc. or lamps.

A method has been proposed in which a single-crystal thin film whose crystal orientation matches that of a single-crystal substrate is produced by applying energy beam irradiation such as heating with a heater or the like to melt and recrystallize the film.

This conventionally proposed method is usually shown in Fig. 2 (at
(As shown in bl, an insulating film 22 having a partial opening 21a is formed on a single crystal substrate 21, and an amorphous or polycrystalline non-single crystal thin film 23 to be made into a single crystal is formed on the insulating film 22.
After forming the surface protective film 24, the non-single-crystal thin film 23 is directly contacted with the exposed portion 21a of the single-crystal substrate 21 using an energy beam irradiation 25 such as laser beam or electron beam irradiation or heating with a lamp, heater, etc. By performing this from the region, the non-single crystal thin film 23 is single crystallized using the single crystal substrate 21 as a seed for crystal growth to form a single crystal thin film 26 whose crystal orientation matches that of the single crystal substrate 21.

In addition, when trying to form two or more layers of single crystal thin film,
As shown in FIG. 3 (aJ and (bl), the single crystal substrate 21
There is a method in which the seed is directly used as a seed, and a method in which the single crystal thin film 26 formed so that the crystal orientation matches that of the single crystal substrate 21 is used as the seed, as shown in FIGS. 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 as a seed shown in FIG. Since the step difference becomes large, it is difficult to control the crystal orientation well. There is a method to eliminate the difference in level by filling the seed part with the same material as the thin film 23 to be made into a single crystal in advance, but if there is a large difference in thermal conductivity between the thin film 23 to be made into a single crystal and the interlayer insulating film 22. The temperature difference between the two parts becomes too large, and the thin film 23 in both parts, which is desired to be made into a single crystal, cannot be well melted without any unmelted parts or scattering.

In order to avoid this problem, the single crystal substrate 21 shown in FIG.
There is a method in which the patterned thin film 29 of the lower single-crystal thin film 26, which is formed so that the crystal orientation matches that of When, single crystal thin film 2
The single-crystal thin film 29 around the exposed portion 29a of 9 is also melted. If this molten region spreads over the entire area of the single crystal thin film 29 that is to be the patterned seed, only a thin film with a random crystal orientation will be obtained, even though the single crystal thin film 29 whose crystal orientation has been controlled is intended to be used as a seed. There was a problem.

In addition, Figure 4 fal to (elc oi (, Figure 2 fat
, (bl and FIG. 3 (al, fbl) The same parts are indicated by the same reference numerals, 21 is a single crystal substrate, 21a is an exposed part of the single crystal substrate 21, 22 and 27 are non-single crystal insulating films, 23 and 28 is a non-single crystal thin film to be made into a single crystal, 24
and 30 are surface protective films; 25 and 31 are energy beams Jut irradiated with laser beams, electron beams, etc. or heated by lamps, heaters, etc.; 26 and 33 are single crystal thin films; The crystal thin film 29a is an exposed portion of the single crystal thin film 29 serving as a seed, and 32 is a melted region.

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

Means for Solving the Problems In order to achieve the above object, the present invention melts and remelts a non-single crystal thin film formed on a single crystal substrate covered with a non-single crystal insulating film by energy beam irradiation. In a method of forming two or more layers of single-crystal thin films whose crystal orientation matches that of a single-crystal substrate by crystallization, a layer that is lower than the non-single-crystal thin film that is desired to be single-crystal and whose crystal orientation already matches that of the single-crystal substrate A method for controlling the crystal orientation of a non-single-crystalline thin film that is desired to be single-crystalized using a single-crystalline thin film formed as a seed. The region directly in contact with the underlying single crystal thin film, which is formed so that the crystal orientation matches that of the single crystal substrate, is irradiated with the energy beam, and the melting region melts the contact region and the surrounding single crystal thin film. By forming a large pattern of the single crystal thin film, a single crystal thin film whose crystal orientation matches that of the single crystal substrate is obtained.

In the method using a single-crystal thin film formed so that the crystal orientation matches that of a single-crystal substrate, the non-single-crystal thin film that is desired to be made into a single crystal is formed so that its crystal orientation matches that of the single-crystal substrate. When the area directly in contact with the lower single crystal thin film is melted by energy beam irradiation, this contact area and the surrounding single crystal thin film are also melted. If the melting region of the single-crystal thin film that is desired to be used as a seed spreads over the entire patterned single-crystal thin film, there will be no seed to control the crystal orientation when it solidifies next time, making it impossible to control the crystal orientation. On the other hand, by configuring the melting region of the single crystal thin film to be used as a seed to be smaller than the pattern of this single crystal thin film as in the present invention, there will always remain a region whose crystal orientation matches that of the substrate. Since the crystal grows using the crystal as a seed, it becomes possible to stably form a single-crystal thin film with two or more layers having the same crystal orientation as that of the single-crystal substrate.

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

FIG. 1 (al to (fl) are process diagrams for explaining one embodiment of the present invention, respectively.

First, as shown in FIG. 1 (al), an S+02 film 2 of 2 μm thickness is formed on a single crystal silicon substrate 1 by atmospheric pressure CVD, and the exposed portion of the single crystal silicon substrate 1 is patterned by a normal photolithography method. , a 2 μm square opening 1a is formed.Next, a 0.5 μm thick polycrystalline silicon film 3 is formed by low pressure CVD method, and a 0.26 μm thick 5102 film 4 is further formed by normal pressure CVD method. b
As shown in l, melting width 60 μm, laser power LOW
The T urgon laser beam 5 is scanned at a scanning speed of 100W11/s.
ec, the polycrystalline silicon film 3 is attached to the single crystal silicon substrate 1
The polycrystalline silicon film 3 is single-crystallized using the exposed portion 1a of the substrate 1 as a seed to form a single-crystalline silicon film 6 whose crystal orientation matches that of the single-crystal silicon substrate 1. obtain.

Next, after etching the entire surface of the 1c Si 02 film 4, the single crystal silicon film 6 is patterned by a normal photolithography method to form a single crystal silicon film 7 as a seed, as shown in FIG. 1(C). The size of this seed single crystal silicon film 7 is 50 μm square. Next, a 5102 film 8 with a thickness of 2 μm is formed thereon by atmospheric pressure CVD, and only the portion where the single crystal silicon film 7 to be used as a seed is to be exposed is patterned by normal photolithography to form a 2 μm square opening 7a. do.

Next, as shown in FIG.
After forming a 5i02 film 10 with a thickness of 0.26 pm by method D,
Fig. 1 (S melt 1 of polycrystalline silicon 9 as shown in e+)
An argon laser beam 12 of i 60 μm and a laser power of 8 W is scanned at a scanning speed of 100 W/sec from a region directly in contact with the exposed portion of the single crystal silicon film 7 which is seeded by the polycrystalline silicon film 9 to form the single crystal silicon film 7. A single crystal silicon substrate 1 is formed by monocrystalizing a polycrystalline silicon film 9 as a seed.
A single crystal silicon film 13 having the same crystal orientation is obtained. At this time, the melting width of the single crystal silicon film 7 used as a seed is 30 μm.
It was separately confirmed using a sample in which a polycrystalline silicon film was used instead of the single crystal silicon film 7 that the entire region of the single crystal silicon film 7 used as a seed was not melted.

<Effects of the Invention> As described above, according to the present invention, when forming two or more layers of single crystal thin films having the same crystal orientation as that of a single crystal substrate, the seeds for the second and higher layers of thin films can also be sourced from the single crystal substrate. There is no effect of large steps that would otherwise occur, and the entire region of the single crystal thin film used as a seed melts when the energy beam is irradiated to the upper layer polycrystalline silicon, and random nucleation does not occur. Since crystal growth always uses the unmelted region of the single crystal thin film as a seed, it is possible to stably form a single crystal thin film whose crystal orientation matches that of the single crystal substrate.

[Brief explanation of drawings]

Figure 1 (al to (fl) are process diagrams each showing a cross section of a sample for explaining one embodiment of the present invention, Figure 2 fal
and [b) are process diagrams showing sample cross sections to explain the method of controlling the crystal orientation of one layer of thin film using a single-crystal substrate as a seed, and Fig. 3 (al and [bl) and Fig. 4 (al to [e
1 is a process diagram showing a cross section of a sample for explaining a conventional method for controlling the crystal orientation of two or more layers of R films. 1... Single crystal silicon substrate, la... Exposed portion of single crystal silicon substrate, 2, 4, 8.10... 5i02 film, 3.9... Polycrystalline silicon film, 5, 12...・Argon laser beam irradiation, 6.13...Single crystal silicon film. 7... Single crystal silicon film used as a seed, 7a... Exposed portion of the single crystal silicon film used as a seed, 11... Melted region.

Claims (1)

[Claims] 1. By melting and recrystallizing a non-single-crystal thin film formed on a single-crystal substrate covered with a non-single-crystal insulating film by energy beam irradiation, the crystal orientation can be made to match that of the single-crystal substrate. In the method of forming two or more layers of single-crystalline thin films, single-crystalization is performed using a single-crystalline thin film, which is already formed in a layer below the non-single-crystalline thin film to be single-crystalized, and whose crystal orientation matches that of the single-crystal substrate, as a seed. A method for controlling the crystal orientation of a non-single-crystal thin film that is desired to be made into a single crystal, in which the crystal orientation of the non-single-crystal thin film that is desired to be made into a single crystal coincides with that of a single-crystal substrate when patterning a single-crystal thin film that is used as a seed. The area directly in contact with the lower layer single crystal thin film formed by the above-mentioned energy beam irradiation forms a pattern of the seed single crystal thin film larger than the melting area where the contact area and the surrounding single crystal thin film are melted. A method for producing a single crystal thin film, characterized by: 2. The method for manufacturing 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 or 2, wherein the non-single crystal thin film to be made into a single crystal is silicon.