JPS6265410A - Formation of single crystal thin film - Google Patents

Abstract

PURPOSE:To form a single-crystal thin film of high quality having crystal azimuth identical with a single-crystal substrate on an insulating film, by forming a non-single crystal thin film having a specific difference in film thickness with regard to the insulating film on an exposed area of the single crystal substrate, and making the thin film in this region become single-crystallized, and then forming the non-single crystal thin film as an active layer all over the surface and heating it. CONSTITUTION:Only an exposed region 1a of a single-crystal silicon substrate 1 is embedded with a non-single silicon thin film 3 having thickness nearly equal to that of an insulating film 2. And, the difference in thickness between the thin film 3 and the insulating film 2 is made to be 1.0mum or less. Then, energy beam radiation or heating 5 by a heater, a lamp, or the like is performed to obtain a thin film 4 having a crystal azimuth identical with the substrate 1, with the exposed part 1a serving as a core on the thin film 3. Then, after a non-single crystal silicon thin film 6 is formed as an active layer over both the upper part of the thin film 4 and that of the insulating film 2, heating 8 is performed again with the thin film 4 serving as a core so that the non-single crystal silicon thin film 6 as an active layer is made single-crystalline so as to obtain a single-crystal silicon thin film 7. Hence, the single-crystal thin film of high quality having a crystal azimuth identical with the substrate 1 even if the insulating film grows 1.0mum or more thick.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for forming a single crystal thin film used in the field of manufacturing semiconductor devices, and more specifically relates to a method for forming a single crystal thin film formed on an amorphous substrate. Or CW on non-single crystal thin film such as polycrystalline.
This invention relates to improvements in methods for converting non-single crystal thin films into single crystals by irradiating energy beams such as laser beams and electron beams, or by heating with heaters, lamps, etc.

Conventional technology> Conventionally, a non-single-crystal thin film of poor quality or polycrystalline material is formed on an insulating film that does not have crystallinity, and this non-single-crystal thin film is irradiated with an energy beam or exposed to a heater or lamp. A method of producing a single crystal thin film by melting and recrystallizing it by heating with etc. (so-called 501 (Silic
On On In5ulator) technology) has been proposed. The conventionally proposed method is usually the second one.
As shown in FIGS. (a) and (b), an insulating film I2 is formed on the silicon substrate 11, and an amorphous or polycrystalline non-single crystal silicon thin film 13 is further formed thereon (a second
In Figure (a)), the non-single crystal silicon thin film 13 is single-crystallized by heating 14 using a reheater or lamp that irradiates energy beams to obtain a single-crystalline film 15 (Figure 2 (b)). .

However, the silicon single crystal film 1 obtained by such a method
It is very difficult to control the crystal orientation of 5.

Therefore, as shown in FIGS. 3(a) and 3(b), an insulating film 1 is placed with a part 11a of the single crystal silicon substrate 11 exposed.
After forming 6, a non-monocrystalline silicon film 17 is formed, and the area where the non-monocrystalline silicon film 7 is directly exposed to the exposed portion 11a of the single-crystal silicon substrate 11 is heated by energy beam irradiation or heating 14 using a heater or lamp. By performing the steps from
A high-quality single-crystal silicon thin film 18 whose crystal orientation matches that of
I am getting .

<Problems to be Solved by the Invention> However, in the conventional method described above, the thickness of the insulating film 16 between the single crystal silicon substrate 11 and the non-single crystal silicon film 17 to be single crystallized is 1 μm or more. Because of the steep and large step difference that occurs in the exposed portion 11a of the single crystal silicon substrate 11, crystal growth occurs from the non-single crystal silicon thin film 17 in the area in contact with the single crystal silicon substrate 11 to the non-single crystal silicon thin film on the insulating film 16. will no longer occur continuously. Therefore, there are problems such as not being able to obtain a single crystal silicon thin film that matches the crystal orientation of the single crystal substrate 11.

The present invention was devised in view of these points, and provides a single crystal thin film forming method for forming a high quality single crystal thin film with a controlled crystal orientation by energy beam irradiation or heating with a heater or lamp. It is an object.

<Means for Solving the Problems> In order to solve the above problems, the single crystal thin film forming method of the present invention first forms a film with a thickness approximately equal to the thickness of the insulating film only on the exposed area of the single crystal substrate. After forming a non-single crystal thin film, irradiating the non-single crystal thin film in this region with an energy beam or heating it with a heater or lamp, the thin film in this region is made into a single crystal. Forms a crystal thin film. Next, a single crystal thin film is formed on the insulating film by irradiating the insulating film with an energy beam or heating it with a heater, lamp, or the like.

Effect> By forming in advance a single crystal thin film having a thickness almost equal to the thickness of the insulating film only on the exposed area of the single crystal substrate and forming a single crystal, it is possible to form a single crystal thin film with a thickness of 1.0 μm or more, for example, 5.
．． Even if the thickness is about 0 μm, a high-quality single-crystal thin film with the same crystal orientation as the single-crystal substrate can be obtained using the above-mentioned single-crystalline thin film as a seed.

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

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

First, an insulating film 2 is formed on a single crystal silicon substrate 1 shown in FIG. 1(a) with a portion of the single crystal silicon substrate 1 exposed (exposed portion 1a) as shown in FIG. 1(b). Next, a first film is applied only to the exposed region 1a of this single crystal silicon substrate 1.
As shown in FIG. 3(c), a non-single crystal silicon thin film 3 having a thickness substantially equal to that of the insulating film 2 is embedded.

Note that the difference in thickness of the non-single crystal silicon thin film 3 formed at this time from the thickness of the insulating film 2 is set to be 1.0 μm or less.

Next, in this state, as shown in FIG. 1(d), energy beam irradiation or heating 5 using a heater, lamp, etc. is performed to convert the non-single crystal silicon thin film 3 on the exposed portion la of the single crystal silicon substrate 1 into a single crystal. Exposed portion 1 of silicon substrate 1
A is used as a seed for single crystallization to obtain a thin film 4 whose crystal orientation matches that of the single crystal silicon substrate I. Next, as shown in FIG. 1(e), after forming a non-single-crystal silicon thin film 6 that will become an active layer on the upper part of the monocrystalline thin film 4 and the upper part of the insulating film 2,
Again, as shown in FIG. 1(f), the monocrystalline thin film 4 is irradiated with an energy beam or heated 8 with a heater, lamp, etc.
The non-single-crystal silicon thin film 6, which will become the active layer, is single-crystallized using the single-crystal silicon thin film 4 as a seed to obtain a single-crystal silicon thin film 7.

In this way, a single-crystal silicon thin film 7 whose crystal orientation matches that of the single-crystal silicon substrate 1 is obtained.

<Effects of the Invention> As described above, according to the present invention, for example, one
．． Even if an insulating film with a thickness of 0 μm or more is coated, the insulating film can be coated with a crystal orientation that matches that of a single crystal substrate. Figure 2 (a) is a process diagram showing the sample cross section for
, (b) and FIGS. 3(a) and 3(b) are schematic diagrams showing a cross section of a sample for explaining the conventional single crystal thin film forming method, respectively.

l...Single crystal silicon substrate, la...Exposed portion, 2
...Insulating film, 3...Non-single crystal silicon thin film, 4...
・Single crystal silicon thin film, 5 and 8...Heating with energy beam irradiation or heater lamp, etc., 6...
Non-monocrystalline silicon thin film serving as an active layer; 7... Single-crystalline silicon thin film serving as an active layer.

Agent: Patent Attorney Fuku Aihiko (2 others) No. 11 Figure 2 3rd yIJ

Claims (1)

[Claims] 1. A step of coating an insulating film on the single crystal substrate so that a portion of the single crystal substrate is exposed, and a step of coating a non-single crystal thin film only on the partially exposed region of the single crystal substrate. a step of irradiating the non-single crystal thin film with an energy beam or heating it with a heater, a lamp, etc. to single-crystallize the thin film using the exposed portion of the single-crystal substrate as a seed; and an upper part of the single-crystal thin film. and a step of forming a non-single-crystalline thin film to serve as an active layer in both areas above the insulating film, and a single-crystalline thin film formed on the exposed portion of the single-crystal substrate by irradiating an energy beam or heating with a heater, lamp, etc. A method for forming a single-crystal thin film, comprising the step of single-crystallizing the non-single-crystal thin film to become the active layer using as a seed. 2. A patent claim characterized in that the difference between the thickness of the non-single-crystal thin film formed on the exposed region of the single-crystal substrate and the thickness of the insulating film covering the single-crystal substrate is 1.0 μm or less. A method for forming a single crystal thin film according to scope 1. 3. The method for forming a single crystal thin film according to claim 1, wherein the single crystal substrate is a silicon single crystal, and the thin film to be single crystallized is a silicon thin film.