JP2919145B2 - Laser light irradiation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser beam irradiating apparatus for performing processing using a laser beam, and more particularly to an improvement of a laser beam irradiating apparatus used for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art Hitherto, a so-called SOI (Silicon On Insulator) technique for forming a single crystal semiconductor layer on an insulator has been developed. Then, a laser annealing technique for irradiating the polycrystalline semiconductor layer deposited on the insulator with a narrowly focused laser beam to monocrystallize the polycrystalline semiconductor layer keeps the temperature of the semiconductor substrate during processing low. Therefore, it is used as an SOI forming technique for a three-dimensional circuit element. The above laser annealing technique is also applied to the activation of ion-implanted impurities and the laser CVD (chemical vapor deposition) technique for selectively forming a film on a semiconductor substrate using laser light. I have.

FIG. 4 is a configuration diagram of a laser annealing apparatus to which a conventional laser annealing technique is applied.
1 is a 20 W output argon ion laser oscillator (hereinafter referred to as
A light-blocking shutter 2 (hereinafter simply referred to as a laser) is provided on the optical path of the laser light and includes a mirror-rotating galvano scanner 2b and a cooling unit 2a, which turns on and off the laser light oscillated from the laser 1 at a high speed. , Simply referred to as a shutter),
2b is a mirror-rotating galvano scanner that does not require 10 msec to rotate an angle of about 20 degrees, 2a
Is a heat sink made of Al which has been subjected to black alumite processing for absorbing the laser light reflected by the galvano scanner 2b and forcibly cooling it. 3 is composed of two lenses, and has a diameter of 3 for the laser light not blocked by the shutter 2. A beam expander that has been enlarged about twice to make it easier to narrow the beam diameter of the laser beam during operation, 4a to 4d are fixed mirrors, 5a is λ /
2 plate and 5b are polarizing prisms, 5 is a λ / 2 plate 5a and a polarizing prism 5b, a beam power adjuster for adjusting the output of the passing laser beam, 6 is a rotating mirror,
A galvano scanner that scans the laser light in the X direction, 7 is an fθ lens designed to narrow the laser light to a beam diameter of 50 μm to 100 μm, and that the beam diameter and the scanning speed are not changed by scanning in the X direction; A single-axis precision stage in which a galvano scanner 6 and an fθ lens 7 are installed and movable in the Y-axis direction, 9 is a semiconductor wafer, 10 is an installation table for holding the semiconductor wafer 9 by a vacuum chuck, and 11 is an installation table 10 400 to 50 semiconductor wafers 9
An infrared lamp for heating to a temperature of 0 ° C .;
Reference numeral 13 denotes an N ₂ gas introduction pipe provided in the chamber 12 so as to fill the inside of the chamber 12 with an N ₂ atmosphere so that the surface of the semiconductor wafer 9 is not oxidized during laser light irradiation. It is a panel that covers components.

Next, the operation will be described. The laser light oscillated from the laser 1 is expanded into a beam having a diameter of about 10 mm by the beam expander 3, adjusted to an appropriate power by the beam power adjuster 5, and guided to the galvano scanner 6. And galvano scanner 6
Is reflected by the fθ lens 7 to have a diameter of 1 mm.
500 μm by infrared lamp 11
Irradiates the semiconductor wafer 9 that has been heated. Here, the laser light is scanned in the X direction in a predetermined area of the semiconductor wafer 9 by the rotation of the galvano scanner 6, and when one scan is completed, the galvano shutter 2b is rotated and the laser light is transmitted to the cooling unit 2a. The shutter 2 is closed. Then, while the laser beam is shut off, the galvano scanner 6 is returned to the initial position of the scanning,
The stage 8 moves by 80 μm in the Y direction. After the stage 8 moves in the Y direction and completely stops, the shutter 2 opens again, the galvano scanner 6 rotates, and the second scanning of the laser beam starts. In this way, the entire area of the semiconductor wafer 9 is irradiated with the laser light while scanning with the laser light,
Processing is performed.

[0005] Here, FIG.
fθ lens 7, stage 8, semiconductor wafer 9, installation table 1
0, infrared lamp 11, chamber 12, gas inlet tube 13
Is a side view of the arrangement portion of, as can be seen from the figure, the laser light during irradiation of the laser beam is in a state of intersecting always perpendicular to the semiconductor wafer 9 sides, irradiation morphism light to the semiconductor wafer by scanning the X-direction May be incident perpendicularly.

FIG. 6 is an enlarged view in which the beam power adjuster 5 is partially enlarged. The mechanism for adjusting the laser power by the power adjuster 5 is such that the polarizing prism 5b is used for a polarized light having a wavefront in the YZ directions. 97% of that
Is reflected and 2% is transmitted. In addition, 2% of the polarized light having a wavefront in the XZ direction is reflected and 97% is transmitted.
By rotating the λ / 2 plate 5a, the ratio between the polarized light having the wavefront in the YZ direction and the polarized light having the wavefront in the XZ direction is changed, and only the transmitted light from the polarizing prism 5b reaches the semiconductor wafer 9 surface. The output of the laser light on the semiconductor wafer 9 is adjusted.

[0007]

In order to manufacture an SOI (three-dimensional circuit element) at a high yield, it is necessary that beam scanning is uniform and laser power is stable during processing. is there. However, in the conventional laser beam irradiation apparatus, the semiconductor wafer 9, the mounting table 10, and the chamber 12 are heated to 400 ° C. to 500 ° C. by the infrared lamp 11.
The heat generated by the infrared lamp 11 caused convection in the atmosphere in the panel 14, and the convection disturbed the atmosphere in the panel 14. Then, due to the disturbance of the atmosphere, the optical path of the laser beam irradiated on the semiconductor wafer 9 is bent, causing a meandering of the beam to generate a crystal defect, thereby reducing the yield of the three-dimensional circuit element. was there.

In the above-mentioned conventional apparatus, when 10 W of laser light is perpendicularly incident on the substrate, 39% of the light is reflected from the substrate. Then, the reflected light is reflected and blocked by the polarizing prism 5b so that the reflected light does not return directly into the laser main body.
Approximately 2% was transmitted and returned to the laser body. Therefore, when returning to the laser main body, the return light having an output of about 0.1 W of 1% of the incident light interferes with the laser light emitted from the laser, and the laser light is irradiated vertically on the substrate wafer 9. In this case, there is a problem that an output fluctuation of about 1% is caused within a range of ± 1 cm with respect to the position of the center, thereby causing a crystal defect at the time of recrystallization and lowering the yield of the three-dimensional circuit element. Was.

Although the first problem can be solved by exhausting the atmosphere around the chamber 12, the flow of the atmosphere due to the exhaust is conversely caused by the N ₂ gas flowing on the surface of the semiconductor wafer 9. Disturb the atmosphere of the laser beam and cause the laser beam to meander. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. A laser capable of reducing meandering of a laser beam and, for example, reducing generation of crystal defects in the manufacture of an SOI (three-dimensional circuit element). It is intended to obtain a light irradiation device. Still another object of the present invention is to provide a laser beam irradiation apparatus which does not cause fluctuations in the laser beam output and does not cause an uneven portion in the laser beam output.

[0010]

According to a first aspect of the present invention , there is provided a laser beam irradiation apparatus , comprising: an installation table for installing a workpiece; and heating means provided near the installation table for heating the workpiece. a chamber provided so as to cover the periphery of the mount base and heating means, separating the chamber, provided with a laser optical system having a laser oscillator that is disposed apart from the above the installation base and heating means An insulating wall is provided between the chamber and the optical system, and an air introduction pipe is provided so as to fill the atmosphere around the optical system with a laminar airflow having a constant flow rate, and the air introduction pipe faces the air introduction pipe. In the laser light irradiation device provided with the arranged air discharge pipe,
The area on the chamber side of the two areas separated by the hot wall
And a stage provided on the stage.
Optical components on which laser light from the
The laser oscillating from the laser oscillator provided in the optical system
An adjustment system for adjusting the output of the laser beam;
By moving the laser and the optical component, the laser
Scans the laser beam that has reached the above optical components from the oscillator
The workpiece is irradiated with the laser light,
Make sure that the laser light does not enter the surface of the workpiece vertically.
The stage and the above optical components are arranged respectively.
is there.

[0011]

In the laser light irradiation apparatus according to the present invention,
The insulation wall blocks the chamber from the optical system, and
Around the optical system with the air introduction pipe and air discharge pipe
Atmosphere can be filled with a constant flow of laminar airflow.
Wear. This makes the atmosphere in the chamber stable.
And the atmosphere around the optical system can be
It is possible to achieve a stable state without disturbance,
As a result, meandering of the laser light on the traveling path can be suppressed. Further, in the laser beam irradiation apparatus according to the present invention, the laser beam is prevented from being vertically incident on the surface of the workpiece.
Since it is possible that the reflected light overlaps with a laser oscillator side
Therefore, interference of laser light can be prevented.
In addition, it has an optical system that adjusts the output of laser light.
Therefore, suppose that the laser beams overlap on the laser oscillator side.
Even if reflected, this optical system suppresses the output of reflected light.
As a result, laser light interference can be suppressed .

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a configuration diagram of a laser beam irradiation apparatus according to an embodiment of the present invention. The same reference numerals as those in FIG. 4 denote the same or corresponding parts, 1 is a laser, 2 is a shutter, 3 is a beam expander, 4a, 4b, 4c, 4d are fixed mirrors, 5 is a beam power adjuster, 6 is a galvano scanner, 7 is f
Theta lens, 8 is a stage, 9 is a semiconductor wafer, 10 is a mounting table, 11 is an infrared lamp, 12 is a chamber, and 13 is N
_{2 is an} introduction pipe, 14 is a panel, 15 is a heat insulating wall, 16 is an air introduction pipe, and 17 is an air exhaust pipe.

The operation will be described below. The basic operation of the above laser light irradiation device is the same as that of the conventional laser light irradiation device shown in FIG. 4, and the description of the basic operation is omitted.

The atmosphere in and around the chamber 12, the light blocking shutter 2, the beam expander 3,
The heat insulating wall 15 provided so as to block the atmosphere around the optical system including the fixed mirrors 4a to 4d, the beam power adjuster 5, etc., makes 80% of the total laser beam path length of the laser beam emitted from the laser 1 80%. Since the occupied atmosphere is cut off from the heated atmosphere around the chamber 12 and the air flows from the air introduction pipe 16 to the air exhaust pipe 17 in a layered manner, 80% of the total laser optical path length is obtained.
Becomes a laminar flow atmosphere, and the laser light traveling in this atmosphere is a laser light having a small meandering within ± 4 μm. Then, the laser beam having little meandering passes through an opening formed in a part of the heat insulating wall 15 and is irradiated on the semiconductor wafer 9 by the galvano scanner 6 and the fθ lens 7.

FIG. 2 is a side view showing the arrangement of the galvano scanner 6, the fθ lens 7, the stage 8, the semiconductor wafer 9, the mounting table 10, the infrared lamp 11, and the chamber 12. In the laser beam irradiation apparatus of this embodiment, The stage is inclined obliquely to prevent the laser beam from being vertically incident on the surface of the semiconductor wafer 9. FIG. 3 is an enlarged view of the incident light and the reflected light on the surface of the semiconductor wafer 9, and in FIG.
Represents incident light, 19 represents reflected light, θ and φ represent angles, and x represents length.

Here, in order to prevent the interference of the laser light, the incident light 18 and the reflected light 19 are shifted from the fθ lens 7 toward the laser body so that the return light 19 from the semiconductor wafer 9 does not enter the laser body 1. Must not overlap. Therefore, the incident angle θ needs to satisfy the range obtained by the following calculation.

For example, if the beam diameter is 6.0 mm (=
6.0 × 10 ³ μm) laser beam is incident on the fθ lens and is 30 cm (= 3.0 × 10 ⁵ μm) from the fθ lens.
The beam diameter is 100 μm on the remote semiconductor wafer 9 surface.
When condensing light so that
Here, the beam diameter on the surface of the semiconductor wafer 9 is 100 μm.
m is extremely small compared to other values, and it is considered that the beam is focused on the semiconductor wafer 9 at one point.

Tan (θ + φ) = ( 6.0 × 10 ³ + x ) /3.0×10 ⁵ (1) tan (θ−φ) = x / 3.0 × 10 ^5.・ ・ ・ ・ ・ ・ ・ ・ （２）

Then, in order for the incident light 18 and the reflected light 19 not to overlap, x> 0 must be satisfied. When x = 0, θ = φ, and θ 、 1 ° is obtained. Therefore, the incident angle θ
Is greater than 1 °, the return light will not return into the laser body. On the other hand, when the incident angle θ is larger than 14 °, the power density of the laser beam on the semiconductor wafer 9 decreases,
A temperature distribution occurs in the semiconductor wafer 9, making it difficult to control crystal defects. Therefore, the incident angle θ is 1 ° <θ.
It is preferable to select from the range of <14 °.

Here, experimentally, a laser beam having a diameter of 6 mm is focused on the surface of the semiconductor wafer 9 to a diameter of 100 μm, the fθ lens 7 is separated from the surface of the semiconductor wafer 9 by 300 mm, and the incident angle with respect to the surface of the semiconductor wafer 9 is changed. When the laser beam having a diameter of 6 mm is incident on the surface of the semiconductor wafer 9 to form a single-crystal semiconductor layer so that the angle always becomes 5 °, no interference occurs due to the laser beam, and the unstable laser beam Is not supplied, and a single-crystal semiconductor layer having good crystallinity is obtained.

In the laser beam irradiation apparatus of this embodiment, the atmosphere in and around the chamber 12, the light blocking shutter 2, the beam expander 3, the fixed mirrors 4a to 4d, the beam power adjuster 5, etc. The atmosphere surrounding the optical system consisting of
The atmosphere around the optical system is an air introduction pipe 16.
And the air exhaust pipe 17 are filled with air flowing at a constant flow rate in a laminar flow, so that the atmosphere around the optical system is not disturbed by heat and becomes an atmosphere in a laminar flow in a constant state. The atmosphere around the chamber can also be kept in a stable state. As a result, meandering of the laser light on the traveling path can be suppressed, and the occurrence of crystal defects and the like can be prevented, and the yield during manufacturing can be improved. .

Further, in the laser beam irradiation apparatus of this embodiment,
The galvanometer scanner 6, fθ lens 7, stage 8, semiconductor wafer 9, mounting table 10, infrared lamp 11,
Since the optical components such as the chamber 12 are arranged, the incident angle of the laser beam on the surface of the semiconductor wafer 9 becomes larger than 1 °, and the laser beam incident on the surface of the semiconductor wafer 9 (incident light 1)
8) and the reflected light 19 from the surface of the semiconductor wafer 9 can be prevented from interfering with the laser light without overlapping the fθ lens 7 on the laser main body side. As a result, the output fluctuation on the surface of the semiconductor wafer 9 does not occur and the crystal defect is not generated. It is possible to form a good crystal layer without any defects, and to improve the yield during manufacturing.

In the above embodiment, the air flows in the direction of arrow Z in the drawing by the air introduction pipe 16 and the air exhaust pipe 17, but the air may flow in other directions. The same effects as those of the above embodiment can be obtained. Further, in the above embodiment, the scanning of the laser beam is performed by the galvano scanner 6 and the stage 8, but another scanning method may be used, and the laser beam may be prevented from vertically entering the semiconductor wafer.

[0024]

As described above, according to the present invention, the atmosphere in and around the chamber and the atmosphere around the optical system are isolated from each other, and the atmosphere around the optical system is made to flow in a layered manner. Therefore, it is possible to obtain a laser light irradiation device that does not meander in the traveling of laser light. As a result, when this laser light irradiation device is applied to laser annealing technology, a good semiconductor crystal without crystal defects can be formed. Therefore, there is an effect that the yield at the time of manufacturing a three-dimensional circuit element or the like can be improved.

According to the laser beam irradiation apparatus of the present invention, the optical components are arranged so that the laser beam does not enter the surface of the workpiece such as the surface of the semiconductor wafer perpendicularly. The output fluctuation due to the interference is eliminated, and a laser light irradiation device having excellent laser light output uniformity can be obtained. When this laser light irradiation device is applied to the laser annealing technology, similar to the above, it is possible to obtain a good laser defect free crystal defect. Since such a semiconductor crystal can be formed, there is an effect that the yield at the time of manufacturing a three-dimensional circuit element or the like can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a laser beam irradiation device according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a laser light irradiation unit of the laser light irradiation device according to the first embodiment of the present invention.

FIG. 3 is a diagram of a laser beam irradiation unit according to the first embodiment of the present invention.

FIG. 4 is a block diagram of a conventional laser beam irradiation device.

FIG. 5 is a block diagram of a laser light irradiation unit in a conventional laser light irradiation device.

FIG. 6 is a detailed view of a beam power adjuster in a conventional laser light irradiation device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Laser oscillator 2 Shutter 3 Beam expander 4 Fixed mirror 5 Beam power adjuster 6 Galvano scanner 7 fθ lens 8 Stage 9 Semiconductor wafer 10 Installation table 11 Infrared lamp 12 Chamber 13 N ₂ gas introduction pipe 14 Panel 15 Heat insulation wall 16 Air introduction Pipe 17 Air exhaust pipe 18 Incident light 19 Reflected light

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Kazuyuki Sugahara 4-1-1 Mizuhara, Itami-shi, Hyogo Mitsubishi Electric Corporation, within SSI Research Institute (56) References JP-A-3-291674 (JP) JP-A-1-274001 (JP, A) JP-A-1-148485 (JP, A) JP-A-60-234790 (JP, A) JP-A-4-10614 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) H01S 3/00 B23K 26/08

Claims (1)

(57) [Claims] An installation table for installing a workpiece, a heating means provided near the installation table for heating the workpiece, and a heating means provided to cover a periphery of the installation table and the heating means. a chamber which is, at a said chamber, said installation base and the laser optics and the Bei <br/> example Rutotomoni having a laser oscillator that is disposed apart from the heating means, between the chamber and the optical system An air-insulating wall was provided therebetween, and an air introduction pipe was provided so as to fill the atmosphere around the optical system with a laminar airflow at a constant flow rate, and an air exhaust pipe arranged opposite to the air introduction pipe was provided. For laser light irradiation equipment
In addition, among the two regions separated by the heat insulating wall,
Stage provided in the region on the
Light into which laser light from the provided laser oscillator is incident
Parts and the laser oscillator provided in the optical system.
An adjustment system for adjusting the output of the laser light oscillating from
For example, to be moved and the stage and the optical components
The laser that reaches the optical component from the laser oscillator
Scans the laser beam and irradiates the workpiece with the laser beam.
In addition, the laser light is vertically incident on the surface of the workpiece.
So that the stage and the optical components are
A laser light irradiation device characterized by being placed .