JPH079891B2 - Laser annealing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] A gantry on which an XY stage is mounted and a gantry on which a laser oscillator is mounted are configured so that their relative positions do not change in the low speed scanning direction but can move in the high speed scanning direction. It is an annealing device.

[Industrial application field]

The present invention relates to a laser annealing apparatus, and more particularly to a laser annealing apparatus provided with a means for absorbing vibration when a laser beam is scanned in a high speed scanning direction in laser annealing.

[Conventional technology]

An oxide film (SiO ₂ film) is formed on the surface of a silicon wafer (hereinafter simply referred to as a wafer), and polysilicon is deposited on it.
A silicon on insulator (SOI) that forms a single crystal silicon on a SiO ₂ film by irradiating this polysilicon with a laser beam to melt and cool it.
The technology is known.

The apparatus for laser beam annealing (laser annealing) described above is shown in a sectional view in FIG. 5, in which 31 is a pedestal, on which XY stage 32 is arranged, and a hot chuck is placed thereon. The wafer 34 to be placed and laser annealed 33 is shown mounted on a hot chuck. For example, an oscillator 35 that oscillates an Argon (Ar) laser with a laser power of 12 W is also fixed on the pedestal 31, and a laser beam 36 emitted from the oscillator 35 is focused by a mirror 37 and a lens 38 having a focal length (f) of 70 mm and a diameter of A spot of 40 to 150 μm is irradiated onto the wafer 34, and laser annealing is performed.

[Problems to be solved by the invention]

Referring to FIG. 4, the annealing of the wafer by the laser beam is performed by moving the XY stage 32 in the XY direction to move the wafer 34 with respect to the laser beam, and the laser beam spot on the wafer is indicated by an arrow in the figure. Scan as shown.

In such a laser beam scanning, the laser beam spot (hereinafter referred to as spot) has a diameter of 30 μm.
The spot size is about 5 μm, and high-speed scanning is performed in the Y direction while overlapping (overlapping) the spots by about 5 μm, followed by deceleration, stop, and movement in the X direction, followed by high-speed scanning in the opposite direction. The positioning accuracy in the X direction requires ± 1 μm to surely realize the above-mentioned overlap, while the scanning in the Y direction is performed at a high speed of about 400 mm / sec in order to increase the throughput of laser annealing. The acceleration during deceleration is about 10 m / sec ² , but this deceleration motion needs to be shortened to improve the throughput of laser annealing.

The laser annealing oscillator 35 and the XY stage 32 are fixed to the same pedestal 31 in the conventional example. However, since the vibration due to the high-speed scanning described above is transmitted to the laser oscillator 35, there is a problem that the stability of laser annealing is impaired. The XY stage generally weighs about 10 kg, and the vibration due to its high-speed motion is considerable, and the optical diameter for introducing the laser beam vibrates, causing the spot to swing relative to the wafer. In order to solve such a problem, it was proposed to firmly fix the laser beam oscillator and the XY stage. In that case, it is necessary to fix the oscillation mirror in the laser oscillator. In that case, a mirror for laser oscillation is required. It was found that that method would not solve the problem as it would not be possible to fine-tune.

The present invention was created in view of the above points, and an object thereof is to provide a structure in which the vibration of the XY stage in the laser annealing apparatus due to the high-speed movement does not affect the optical system of the laser beam.

[Means for solving problems]

1 and 2 are views showing an embodiment of the present invention, in which 11 is a first mount, 12 is a second mount, 13 is a spring, 14 is an XY stage, and 15
Is a hot chuck, 16 is a wafer, 17 is a lens, 18 is a laser oscillator, and 19, 20 and 21 are first, second and third mirrors.

In the present invention, the first pedestal 11 and the second pedestal 12 are provided in place of the pedestal that is conventionally provided, and the second pedestal 12 is provided.
Is configured to be movable in the Y direction, which is the direction of high-speed scanning,
The first mirror 19 and the second mirror 20 are fixed to the first mount 11, and the third mirror 21 and the lens 17 are fixed to the second mount 12. The second mount 12 further moves in the X direction while straddling the guides provided on the first mount 11, and at that time, the second mount 12
The horizontal and vertical vibrations of the are suppressed by the rollers 26 and 25.

[Action]

The above-mentioned structure requires the axis (X
It was devised by paying attention to the difference between the axis) and the axis for performing high-speed scanning (Y-axis) so that vibration in the Y direction due to high-speed scanning is not transmitted to the laser oscillator 18.

〔Example〕

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

Referring again to FIG. 1, in the present invention, it is noted that the direction of high speed scanning (Y axis) is different from the direction (X axis) which requires precise positioning accuracy but can be moved by a short distance. Then, the mount on which the XY stage is mounted, that is, the second mount, is the same as the mount on which the laser oscillator is mounted (the first mount 11) and the second mount.
I installed two mounts.

The second mount 12 is arranged not only on the first mount 11, but also in order to absorb the vibration due to the acceleration until the Y-direction high-speed motion of the XY stage 14 slows down and stops, so that the vibration extending in the Y-direction is absorbed. It is fixed to the second mount via an absorbing member such as a spring 13.

On the other hand, the lens 17 for focusing the laser beam directed to the wafer and the mirror immediately before the lens 17, that is, the third mirror 21, are fixed to the second mount 12, and the laser oscillator 18 is also provided.
The first mirror 19 and the second mirror 20 for directing the laser beam emitted therefrom to the mirror 21 are fixed to the first mount. The laser oscillator 18 is mounted on the first mount 11 by the legs 27.
The fixing means for the three mirrors is not shown in FIG. 1, but they are fixed to the first and second mounts by a normal technique.

The second mirror 20 and the third mirror 21 are the second mirror 20
The laser beam reflected from is arranged so as to be parallel to the Y-direction movement direction of the XY stage 14.

In operation, the laser oscillator 18 is turned on to irradiate the laser beam and start operation of the XY stage.
The XY stage 14 makes a high-speed movement in the Y direction, and then decelerates.
It stops and vibrates in the Y direction, and the second gantry 12 responds to the Y
The third mirror 21 for reflecting the laser beam 22 traveling in parallel to the Y direction and the lens 17 for focusing the laser beam reflected from the second mirror 21 are the second mount
Since it is fixed to 12, the vibration of the laser beam becomes zero for the wafer 16 placed on the second pedestal 12, so that the spot fluctuation relative to the wafer does not occur.

In order to improve the accuracy of the movement of the XY stage 14 in the X direction, the means shown in FIG. 2 is used, in which the Y direction is the left-right direction of the figure and the X direction is the direction perpendicular to the paper surface.

The second pedestal 12 is arranged so as to straddle the guide 23 fixed to the first pedestal, and the second pedestal 12 has a pair of rollers 24 (rollers 24 are (Also shown in FIG. 1), an upper roller 25 that suppresses vertical vibrations in the Y-direction movement of the second mount and a pair of side rollers that suppresses Y-direction vibrations of the second mount 12 while suppressing X-direction vibrations. 26
And are provided.

The rollers 25 and the side rollers 26 enable the second pedestal 12 to move with high accuracy in the X-direction without vertical or horizontal vibration.

〔The invention's effect〕

As described above, according to the present invention, high-precision laser annealing can be performed by high-speed scanning, and there is an effect that reliability can be improved and throughput can be improved.

[Brief description of drawings]

 1 and 2 are sectional views of an embodiment of the present invention, FIG. 3 is a sectional view of a conventional example, and FIG. 4 is a plan view showing scanning with a laser beam. In FIGS. 1 and 2, 11 is a first mount, 12 is a second mount, 13 is a spring, 14 is an XY stage, 15 is a hot chuck, 16 is a wafer, 17 is a lens, 18 is a laser oscillator, 19 is a first mirror, 20 is a second mirror, 21 is a third mirror, 22 is a laser beam, 23 is a guide, 24, 25 and 26 are rollers, and 27 is a leg.

Claims (1)

[Claims] 1. An XY stage (14) having a fixed hot chuck (15) on which a wafer (16) is placed, a mirror (21) for reflecting a laser beam (22) toward the wafer, and a mirror (21) The lens (17) for focusing the laser beam is fixed to the second pedestal (12), and the second pedestal (12) is moved in the vertical direction and X by the rollers (25, 26).
The laser oscillator (18) and the laser beam are mirrored (21) fixed to the first frame (11) through a vibration absorbing member (13) capable of suppressing directional vibration and controlling Y-direction vibration.
The mirrors (19, 20) for irradiating the laser are fixed to the first frame (11), and the laser beam (22) traveling from the mirror (20) to the mirror (21) is arranged in the Y direction. Laser annealing equipment.