JPS60145987A - Manufacture of thin film single crystal - Google Patents

Abstract

PURPOSE:To manufacture a large thin film single crystal having improved crystallinity on an insulator, by melting a polycrystalline or amorphous semiconductor layer formed on the insulator by heat to give an interface between a solid and liquid in the form of two peaks with a valley part of an acute angle. CONSTITUTION:The beam diameter of a laser beam (B), e.g. Ar, emitted from a laser beam emitter 21 is enlarged in a beam expander 22, and the beam (B) is passed through a shit hole 24 of a light shielding plate 23 and led to a lens system 25 prepared by removing the central part of one convex lens at a given width, and bonding and integrating the resultant pair of lens pieces at the cut faces. The laser beam (B) after passing through the lens system 25 is a light beam in the form of two peaks, and a sample 28 prepared by coating an insulator with a polycrystalline or amorphous semiconductor layer is irradiated with the resultant laser beam to melt the semiconductor layer by heat. The position of the sample 28 is adjusted to give the interface berween the solid and the liquid in the form of two peaks with a valley part of an acute angle to the hot melt direction on melting by heat.

Description

Detailed Description of the Invention: Industrial Application Field: The present invention relates to a method for manufacturing a thin film single crystal, in which a polycrystalline semiconductor layer or an amorphous semiconductor layer formed on a substrate is irradiated with light to crystallize it. .

Background technology and its problems A single crystal thin film of silicon is made and this single crystal thin film is used to manufacture silicon semiconductor devices such as high-speed LSI (Large Scale Semiconductor Integrated Circuit), r-strip device, three-dimensional IC (Semiconductor Integrated Circuit), etc. Attempts are being made to create one. To solve this problem, currently a thin film of polycrystalline silicon or amorphous silicon is deposited on the insulating film, and this thin film is used as a carbine heater.
After heating and melting with laser light or electron beam,
5KI (5ilicon on engineering 5ulator) which is cooled and recrystallized from a seed crystal to form a thin film single crystal
The technology is being developed. As shown in the perspective view of FIG. 1 and the cross-sectional view of FIG.
, ), a 5i02 film (2) is formed as an insulating film,
Furthermore, a polycrystalline (or amorphous) silicon film (3) is deposited on top of it so as to partially contact the substrate (1), and this polycrystalline (or amorphous) silicon film (3)
The polycrystalline (or amorphous) silicon film (3) is melted by irradiating and scanning the surface of the polycrystalline (or amorphous) silicon film (3) with a laser beam or an electron beam B, and then while cooling. Crystallization is performed using the substrate (1) as a seed crystal. Furthermore, in the crystallization method using a Carpin heater, as shown in the perspective view of FIG. 3 and the cross-sectional view of FIG.
), polycrystalline (or amorphous) silicon film (7), 5i02
The film (6) and the Si 3N4 film (8) are firstly deposited, and a flat carpin heater α is arranged under the substrate (5), and a rod-shaped carpin heater α is placed on the substrate (5). The polycrystalline (or amorphous) silicon film (7) is crystallized by moving the Carmen heater (1B).

The problem with this SO technology is how a large crystalline thin film with good crystallinity can be formed on an insulating film.

In SOI technology using laser light, there are the following two methods for obtaining better single crystals.

The first method uses a Lede beam with a bimodal optical energy distribution. In this method, a bimodal beam is created from a Lede beam using various optical systems, and a linear single crystal film is formed by scanning this bimodal beam. By creating a bimodal beam, a single seed crystal grows in the scanning direction. The second method is to process the substrate to allow heat to escape. This is done by leaving the light energy distribution of the Lede beam as a Gaussian distribution, using a heat dissipating film and a substrate, and depositing an insulating film with a predetermined number of turns with different thicknesses on top of the film and substrate. The deposited polycrystalline (or amorphous) silicon film is melted and recrystallized by the Lede beam.

In this case, heat escapes from the thin insulating film portion, forming a crystal film according to the pattern.

By the way, in the first method of recrystallization using a bimodal Lede beam, it is not possible to easily obtain a single crystal film with good crystallinity using a bimodal beam; The problem is the shape of the boundary line between the same phase and the liquid phase when a polycrystalline silicon film is melted. Single crystals obtained by conventional recrystallization using a simple bimodal beam do not have very good crystallinity, and it is difficult to obtain large single crystals.

Purpose of the Invention In view of the above-mentioned points, the present invention provides a method for producing a thin film single crystal that more reliably obtains a large thin film single crystal with good crystallinity in a method for producing a thin film single crystal by recrystallizing using a Lede beam. This is what we provide.

Summary of the Invention The present invention provides a method for producing a thin film single crystal in which a polycrystalline semiconductor layer or an amorphous semiconductor layer formed on an insulator is heated and melted, and then cooled to grow a single crystal from a seed crystal. A method for producing a thin film single crystal in which the shape of the solid-liquid phase interface formed by heating a semiconductor layer or an amorphous semiconductor layer is bimodal in the direction of heating and melting, and the angle formed by the valley of the bimodal shape is an acute angle. It is.

In the present invention, a large single crystal with good crystallinity can be obtained during recrystallization of a polycrystalline semiconductor layer or an amorphous semiconductor layer.

EXAMPLE Hereinafter, an example of the method for producing a thin film single crystal according to the present invention will be described with reference to FIG. 5 and subsequent figures.

FIG. 5 shows an embodiment of a manufacturing apparatus applied to the present invention. In the figure, eυ is a Lede beam generator that generates a Lede beam B of Ar, for example, and the Lede beam B from this generator 12υ is a beam extractor mother beam C! After enlarging the diameter of the beam, the lens system 125 passes through the slit-shaped hole (2) of the light shielding plate 123 to create a bimodal beam.
I am guided by 1. The Lede beam B transmitted through the lens system f29 is reflected by a reflecting mirror C, and then irradiated onto a sample 2ip placed on a stage 127) movable in the X and Y directions. Sample 12 is made by depositing a polycrystalline silicon film or an amorphous silicon film on a glass or silicon crystal substrate as described above through a 5i02 layer.

An example of a lens system (2ω) that creates a bimodal beam light is shown in Figure 6. In this example, when two convex lenses with the same radius of curvature are superimposed on the same plane, the shared part of both lenses is (The part surrounded by a solid line corresponds to a composite lens using
A pair of lens pieces L1. It can be made by preparing L2 and combining Ll and L2 with a transparent adhesive or the like. When the combined lens L is irradiated with the Lede beam B, the parallel Lede beam B incident on Ll is focused on Fl, and the parallel Lede beam B incident on L2 is focused on F1.
Focus the light on 2. That is, this composite lens L creates two Radhe beams B whose optical axes are offset from each other by d,
The Lede beam B before entering the composite lens L has a Gaussian optical energy distribution with a peak at the center, so after passing through the composite lens L, the optical energy distribution will be different before and after the position F'1'-F2. A bimodal beam with different values is created. For example, at the A-A' position before 1i11-F2, Ll and the end of the beam incident on Ll enter the center, so a bimodal beam with a small concavity in the center is obtained, and Fl-F2 At the far rear position B-8', a bimodal beam with a large concavity in the center is obtained.

Now, in the manufacturing apparatus shown in Fig. 5, the Radhe beam B that has passed through the slit-shaped hole (C) has the cross-sectional shape shown in Fig. 7, and passes through the lens system (C) to become a bimodal beam to be sampled. (
irradiated to). At this time, if the distance between the lens system i2!9 and the sample 210 is adjusted so that the sample (to) is placed 9 points in front of the focal point of the lens system (c), 2
The divided radar beam B is irradiated onto the sample. Since the optical energy distribution of this laser beam B has a Gaussian distribution, the polycrystalline (or amorphous)
A melted region having the shape shown in FIG. 9 is formed on the silicon film. The shape of this melting region is determined by the slit width d1 of the hole in the second floor of the light-shielding plate t', the diameter D1 of the Lede beam when irradiating the sample (two barrels), the snolit width d2 of the focal point, etc. As shown in Fig. 11, the solid-liquid phase interface shape has a bimodal shape with respect to the heating and melting direction a, and the angle θ formed by the valley portion of the bimodal shape becomes an obtuse angle or an acute angle. In the case of the obtuse angle shown in Figure A, the recrystallized part (notch is the peripheral part (30b) as shown in Figure 10B).
), the crystal grain boundaries are densely populated, and in the central region (30a), the crystal grain boundaries become coarse, but the result is a crystal film containing grain boundaries. Figure 11A
In the case of an acute angle of , the recrystallized portion (end) becomes a single crystal film with almost no grain boundaries in the central portion (30a), as shown in FIG. 11B. Therefore, the shape of the melted region (c) during recrystallization is preferably such that it has a bimodal shape in the direction of heating and melting, and the angle θ formed by the valley portion is an acute angle.

The reason for this can be considered as follows. As shown in Figure 12, when the crystal plane (paper surface) of the recrystallized film is (100), the solid-liquid phase occurs when a polycrystalline silicon film or an amorphous silicon film is heated and melted with a linear heating source. The interface has a zigzag mountain-shaped boundary line that is a combination of boundary lines 04 in the (110) direction. In order to promote this property, the melting point temperature distribution must be set at an angle more acute than the actual angle of 90° at the solid-liquid phase interface determined by the (110) direction (θ≦90°), as shown by the symbol (G).
) and scan the laser beam. By doing so, a single crystal film with good crystallinity can be obtained.

Effects of the Invention As described above, according to the present invention, the shape of the solid-liquid phase interface obtained by heating and melting a polycrystalline semiconductor layer or an amorphous semiconductor layer is made bimodal in the direction of heating and melting, and the valleys of the bimodal shape are A large single crystal film with good crystallinity can be obtained by controlling the bimodal laser beam to perform recrystallization so that the angles formed by the parts become acute angles.

[Brief explanation of the drawing]

Figures 1 to 4 show examples of conventional manufacturing methods; steel perspective views and cross-sectional views; Figure 5 is a configuration diagram showing an embodiment of the manufacturing apparatus applied to the present invention; An explanatory diagram showing an example of a lens system. Figures 7 and 8 are cross-sectional views showing the cross section of the laser beam after passing through the slit-like hole and lens system of the apparatus in Figure 5. 10 and 11 are diagrams showing the shape of the region, FIGS. 10 and 11 are explanatory diagrams showing the relationship between the shape of the melted region and the recrystallized state, and FIG. 12 is a diagram used to explain the present invention. (2υ is the Lede beam generator, (c) is the beam extractor/
1. (Incorporated) is the hole, (C) is the lens system, (Incorporated) is the sample, CI is the molten region, and B is the Lede beam. Agent Sadado Ito Hidemori Matsukuma Figure 1 Figure 2 Figure 3 Figure 5 Figures 2 and 6) Xi Figure 12 Procedural Amendments May 1980 101-1 1. Indication of the case 1988 Patent application No. 247802 2° Invention n Name Method for manufacturing thin film single crystal 3, relationship to the amended case '11〒1i71: Applicant address 6-7-35, Kitashinyo, Tokyo Parts Co., Ltd. Name (218) Sony Co., Ltd. Representative Director Nori Oga F4, Agent Tokyo Shoribane 11-ku Nishi-Shinjuku 1 'T I
"8-1 Uriti Hill) Tokyo (03) 343-5
82+ (Representative) 6. Number of inventions increased by supplementation 8. Contents in sleeve 1 (1)% The scope of claims is amended as shown in the attached sheet. (2) In the specification, page 3, line 17, "seed crystal" is corrected to 1-crystal nucleus. (3) Same, page 5, line 4, “From seed crystal” is deleted. Claims A method for manufacturing a thin film single crystal in which a polycrystalline semiconductor layer or an amorphous semiconductor layer formed on an insulator is heated and melted, and then cooled to grow a high-efficiency crystal. A method for manufacturing a #film single crystal, in which the shape of the solid-liquid phase interface obtained by heating and melting a crystalline semiconductor layer is bimodal with respect to the heating and melting direction, and the angle formed by the valley portion of the bimodal shape is an acute angle.

Claims (1)

[Claims] In a method for manufacturing a thin film single crystal in which a polycrystalline semiconductor layer or an amorphous semiconductor layer formed on an insulator is heated and melted, and then cooled to grow a single crystal from a seed crystal, the polycrystalline semiconductor layer or amorphous semiconductor layer is A method for producing a thin film single crystal, in which the shape of the solid-liquid phase interface obtained by heating and melting a semiconductor layer is bimodal in the direction of heating and melting, and the angle formed by the valley of the bimodal shape is an acute angle.