JPH0817153B2 - Method for manufacturing silicon thin film crystal layer - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for producing a semiconductor thin film crystal layer in which a single crystal layer, particularly a semiconductor single crystal layer, is grown on an insulating film.

[Technical background of the invention and its problems]

So-called SOI for growing a single crystal silicon layer on an insulating film
The (silicon layer on insulating film) technology is the most important technology for realizing a three-dimensional IC. Among the SOI technologies, the annealing technology using an electron beam is extremely promising because it can anneal a large area. However, the electron beam annealing technique requires the substrate to be placed in a vacuum, which causes the following problems.

4 (a) and 4 (b) are sectional views for explaining the conventional electron beam annealing method. In this method, first, as shown in FIG. 4A, a SiO ₂ film 42 having an opening 42a is formed on a Si substrate 41, and a polycrystalline Si film 43 is formed thereon. Then, the polycrystalline Si film 43 is irradiated with an electron beam 44, and the beam 44 is scanned in one direction. The opening 42a serves as a so-called seed crystal region that propagates crystal information from the single crystal region of the substrate 41 to the polycrystalline Si film 43. In order for the information on the seed crystal region to propagate to the polycrystalline Si film 43 without interruption, it is necessary to solidify the molten layer melted by the irradiation of the electron beam 44 in order from the one closer to the seed crystal. For example, in FIG. 4 (a), A
It is necessary to solidify in the order of → B → C.

However, in the electron beam annealing technology,
Since the system is placed in a vacuum, there is a problem that the temperature distribution for solidifying in the order of A → B → C cannot always be obtained. That is, as shown by arrows 45 and 46 in FIG. 4A, the heat of the melted polycrystalline Si film 43 is transferred to the insulating film 42 by the heat conduction 46.
Alternatively, the heat radiation 45 from the surface of the polycrystalline Si film 43 causes diffusion, but the thermal conductivity of the insulating film 42 is low in the first place, and the heat radiation 45 is smaller than the heat dissipation by the heat conduction 46. As a result, heat is hard to be accumulated and hardened in the polycrystalline Si film 43, and depending on the shape of the element formed on the substrate under the insulating film, heat conduction may occur depending on the case, although it is far from the seed crystal region. Fast solidification occurs at some good points. Therefore, the fourth
As shown in FIG. 6B, there is a problem that the single crystal is broken to form a polycrystalline region 47.

[Object of the Invention]

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to make it possible to solidify sequentially from the side close to the seed crystal in the melting region by electron beam annealing, and to perform stable single crystallization. It is to provide a method for manufacturing a single crystal layer.

[Outline of Invention]

The essence of the present invention is to use a heat absorber, arrange the heat absorber near the irradiation region on the electron beam irradiation side, and cool the melted region in order from the side closer to the seed crystal.

That is, the present invention forms a SiO ₂ insulating film having an opening portion to be a seed crystal region on a single crystal silicon substrate, deposits an amorphous or polycrystalline silicon thin film on the SiO ₂ insulating film, In a method of manufacturing a silicon thin film crystal layer in which a silicon thin film is irradiated with an electron beam, and the thin film is sequentially melted and recrystallized from the seed crystal region, a silicon thin film rear side of the electron beam irradiation region with respect to a traveling direction of the electron beam A heat absorber that absorbs a part of the heat of the silicon thin film, and the heat absorber is moved together with the movement of the electron beam, whereby the molten silicon thin film is melted into the seed crystal region. The cooling is performed in order from the one closest to

〔The invention's effect〕

According to the present invention, the heat absorber is moved immediately after the electron beam so that the heat absorber is moved along with the electron beam, so that heat is effectively absorbed from the surface of the silicon film in a molten state, and the silicon film becomes a seed crystal region. An ideal steep temperature distribution in which the near side becomes lower is always formed, and the seed crystal can be reliably solidified with the seed crystal as the nucleus. Therefore, stable single crystallization can be performed without breaking the single crystal.

Example of Invention

Hereinafter, the details of the present invention will be described with reference to the illustrated embodiments.

FIG. 1 is a schematic configuration diagram showing an electron beam annealing apparatus used in an embodiment method of the present invention. In the figure, 11 is an electron gun, and the electron beam emitted from the electron gun 11 is focused by the magnetic lenses 12, 13, and 14 and is irradiated onto the sample 16 placed on the stage 15. Reference numeral 17 is a blanking electrode that turns the electron beam on and off. Reference numeral 18 is a heat absorber whose tip is provided in the vicinity of the electron beam irradiation region. The heat absorber 18 is, for example, as shown in FIG. 2, a ceramic body 22 having a stainless tube 21 through which cooling water flows, the tip of which is about 10 [μm] away from the beam irradiation point, Moreover, it is located at a height of about 5 [μm] from the substrate surface.

The sample 16 has an opening 32a on the single crystal Si substrate 31.
Forming a SiO ₂ film (insulating film) 32 having
A Si film (semiconductor thin film) 33 is deposited.

Next, a method of manufacturing a Si thin film crystal layer using the above apparatus will be described.

Electron beam acceleration voltage 10 [KV], beam current 1
[MA], and the beam 34 is reflected on the sample 16 as shown in FIG.
The sample 16 is moved in the direction opposite to the arrow so that the sample 16 is scanned relative to the arrow. The moving speed at this time is 10 [cm
/ sec]. The temperature of the heat absorber 18 is 20
It was kept at [° C].

As a result, the melt flow region of the polycrystalline Si film 33 is forcibly cooled by the heat absorber 18 sequentially from the side closer to the seed crystal (opening 32a). That is, as shown in FIG. 3 (b), the molten region of the polycrystalline Si film 33 always has a temperature distribution that is solidified in the order of A → B → C. Therefore, a good quality single crystal layer could be obtained without the inconvenience that the single crystal was interrupted and a polycrystalline region was generated.

Thus, according to the method of the present embodiment, the heat absorber 18 is used, the heat absorber 18 is arranged behind the irradiation region of the electron beam 34 with respect to the traveling direction of the electron beam 34, and
By moving 18 along with the movement of the electron beam 34, it is possible to solidify sequentially from the side closer to the seed crystal in the molten region of the polycrystalline Si film 33 by beam annealing. Therefore, stable single crystallization can be performed, which is extremely effective for manufacturing a three-dimensional IC.

The semiconductor thin film to be beam annealed is polycrystalline.
The film is not limited to Si and may be an amorphous Si film. In addition, various modifications can be made without departing from the scope of the present invention.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an electron beam annealing apparatus used in an embodiment method of the present invention, FIG. 2 is a sectional view showing a specific structure of a heat absorber used in the apparatus, and FIG. 3 (a). )
FIG. 4B is a sectional view showing a manufacturing process of a Si single crystal layer using the above apparatus, and FIGS. 4A and 4B are sectional views for explaining problems of the conventional beam annealing method. 11 …… electron gun, 12, ～ .14 …… electromagnetic lens, 15 …… sample stage, 16 …… sample, 17 …… blanking electrode, 18 ……
Heat absorber, 21 …… Stainless steel tube, 22 …… Ceramics body, 31 …… Single crystal Si substrate, 32 …… SiO ₂ film (insulating film), 32
a …… Opening part, 33 …… Polycrystalline Si film (semiconductor thin film), 34…
… Electron beam.

Claims (1)

[Claims] 1. A sample obtained by forming an SiO ₂ insulating film having an opening portion serving as a seed crystal region on a single crystal silicon substrate, and depositing an amorphous or polycrystalline silicon thin film on the SiO ₂ insulating film. In a method of manufacturing a silicon thin film crystal layer in which a silicon thin film is irradiated with an electron beam, and the thin film is sequentially melted and recrystallized from the seed crystal region, an electron beam emitted from an electron gun is focused by a lens system on a stage. And an electron beam annealing device in which a tip of a heat absorber made of a stainless steel tube through which cooling water flows is disposed behind the electron beam irradiation region with respect to the traveling direction of the electron beam. The sample is placed on a stage, the heat absorber is moved along with the movement of the electron beam while irradiating the sample with the electron beam, and the sample is melted by the electron beam irradiation. A method for producing a silicon thin film crystal layer, wherein the silicon thin film is cooled by the heat absorber in order from a position closer to the seed crystal region.