JPH0719745B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] A laser beam is separated using a half-wave plate and a birefringent plate set so as to be rotatable with respect to an optical axis, and two separated beam intensities are separated. Adjustment.

[Industrial application field]

The present invention relates to a method of manufacturing a semiconductor device, and more specifically, a silicon-on-insulator (Silicon
con On Insualator (SOI) single-crystal laser beam irradiation method.

[Conventional technology]

In the formation of a semiconductor integrated circuit, polycrystalline silicon (polysilicon) is deposited on an insulator, for example, a semiconductor substrate, and the polysilicon is irradiated with an energy beam, for example, a laser beam to melt and recrystallize the polysilicon to form a semiconductor. A single crystal silicon layer is formed on a substrate and an element is formed thereon.

Irradiation of the laser beam described above is performed as shown in FIG. 3, and a Gauss type, linearly polarized laser beam 31 is used.
(The upper curve of the laser beam 31 schematically indicates that the laser beam is Gaussian) and passes through the 1/4 wavelength plate 32,
A linearly polarized light is converted into circularly polarized light to obtain a gas-type circularly polarized laser beam 31a. The laser beam 31a is passed through a quartz crystal birefringent plate 33 to be birefringent according to the direction of polarized light. A laser having two peaks instead of a Gauss type. Beam 31b, ie two laser spots of the same size and intensity are created. When this polysilicon is irradiated with the laser beam 31b, the crystallinity is improved in the portion between the two peaks of the laser beam, that is, the silicon single crystal with fewer crystal defects is directly irradiated with the laser beam 31. Crystals are obtained.

[Problems to be solved by the invention]

When the polysilicon 41 shown in the plan view of FIG. 4 is monocrystallized by expanding the region of the monocrystalline silicon 42 by scanning the laser beam a number of times as described above, the laser beam 31b is directed in the direction of arrow I. A grain boundary 43 is formed at the joint between the scans, and it is recognized that a crystal defect exists there.

The present invention was created in view of the above point, and in the process of scanning and recrystallizing polysilicon with a laser beam having two spots, a conventional laser beam scanning method for eliminating crystal grain boundaries is provided. The purpose is to provide.

[Means for solving problems]

The above problem is that in the method of recrystallizing non-single-crystal silicon to obtain single-crystal silicon, a Gaussian, linearly polarized laser beam is passed through a half-wave plate, and a laser beam emitted from the half-wave plate is mixed with a quartz crystal. Of the two laser spots with different intensities, which are obliquely separated with respect to the scanning direction, obtained by adjusting the laser beam emitted from the crystal birefringent plate through the refraction plate by rotating the half-wave plate and the crystal birefringent plate. The problem is solved by providing a method for manufacturing a semiconductor device, characterized by forming non-single-crystal silicon into a single crystal by scanning with a spot having a low intensity first and then forming an element therein.

[Action]

FIG. 1 is a diagram for explaining an embodiment of the present invention, and FIG. 2 is a diagram for explaining the principle of the present invention.

In Figure 1, a Gaussian, linearly polarized laser beam
11 is passed through a rotating half-wave plate 12, the laser beam 11a exiting the half-wave plate 12 is passed through a rotating quartz birefringent plate 13,
The laser beam 11b exiting the quartz crystal birefringent plate irradiates the SOI to form a single crystal, thereby forming an element on the single crystal silicon.

In the above-described method, the laser beam 11b is composed of the spot 14 and the spot 15 larger than the spot 14 as shown in FIG. 2, and the spots 14 and 15 are obliquely arranged. Here, when the laser beam is scanned in the direction indicated by the arrow II, the crystal growth in recrystallization proceeds in the direction indicated by line 16 in FIG. 2, and the crystal grows obliquely with respect to the scanning direction from the already recrystallized region. It is difficult for grain boundaries to occur at the joints of scanning.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Referring to FIG. 1, a Gaussian, linearly polarized laser beam 11 (the upper curve of the laser beam 11 schematically indicates that the laser beam is Gaussian) is a half-wave plate 12.
Be passed through. By using a 1/2 wavelength plate, a linearly polarized laser beam 11 can
You get a different 11a. The rotation angle of this plane of polarization can be arbitrarily controlled by rotating the half-wave plate around the laser beam. When the conventional 1/4 wave plate is used, linearly polarized light changes to circularly polarized light, and when the 1/4 wave plate is used, it is decomposed only equally on the sample surface.
The decomposition ratio can be changed by using a wave plate.

The laser beam 11a emitted from the half-wave plate 12 is passed through the crystal birefringent plate 13 and two spots of two different sizes and intensities are obtained.
A laser beam 11b having 14, 15 is obtained (Fig. 2).
The direction in which the two spots are separated is controlled by rotating the quartz birefringent plate 13 with respect to the laser beam incident axis. Two
The relative intensity of the two spots is determined by the direction of the plane of polarization of the laser beam 11a with respect to the crystal birefringent plate 13. In FIG. 2, 17 is a polysilicon layer on the insulator, and 18 is a single crystal silicon layer formed by laser beam irradiation.

Rotation of the half-wave plate 12 can change the relative intensity of the two beams separated by the crystal birefringence plate 13, and rotation of the crystal refraction plate 13 can change the beam separation direction with respect to the scanning direction. Therefore, the rotations of the half-wave plate 12 and the crystal birefringent plate 13 are adjusted so that the ideal beam shown in FIG. 2 can be obtained.

〔The invention's effect〕

As described above, according to the present invention, single crystal silicon with few crystal defects can be obtained in recrystallization of SOI, and it is effective in improving the yield and reliability of semiconductor device manufacturing.

[Brief description of drawings]

 1 is a partial sectional view showing an embodiment of the present invention, FIG. 2 is a plan view showing the principle of the present invention, FIG. 3 is a partial sectional view of a conventional example similar to FIG. 1, and FIG. It is a top view which shows the problem of a prior art example. In FIGS. 1 and 2, 11, 11a and 11b are laser beams, 12 is a half-wave plate, 13 is a crystal birefringent plate, 14 and 15 are laser spots, 16 is a line indicating the crystal growth direction, 17 Is a polysilicon layer and 18 is a single crystal silicon layer.

Claims (1)

[Claims] 1. A method of recrystallizing non-single crystal silicon (17) to obtain single crystal silicon (18), wherein a Gaussian, linearly polarized laser beam (11) is passed through a half-wave plate (12), The laser beam (11a) emitted from the half-wave plate (12) is passed through the crystal birefringent plate (13), and the laser beam (11b) emitted from the crystal birefringent plate (13) is halved.
Of the two laser spots with different intensities separated obliquely with respect to the scanning direction obtained by adjusting the rotation of the wave plate (12) and the crystal birefringent plate (13), the spot with the weaker intensity is scanned first. A method for manufacturing a semiconductor device, which comprises monocrystallizing non-single-crystal silicon to form an element thereon.