JPH11111641A - Laser annealing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser annealing apparatus in which the actual operation rate is significantly improved by covering the optical window and resonator mirrors with an enclosure, and filling the inside of the enclosure with an inert gas for isolating the optical components from the outer air environment. SOLUTION: A laser tube 21, discharge electrodes 22, optical windows 23, and resonator mirrors consisting of a reflecting mirror 24 and an output mirror 25, are provided in a laser oscillator 11 the entire structure of which is covered with a cover 20. The optical windows 23, the reflecting mirror 24, and the output mirror 25 inside the laser oscillator 11, are covered with a pair of rigid enclosure 28 made of stainless steel, for example, which is combined with the laser tube 21 to form a pair of clean space 29. In the clean spaces 29, N2 gas is supplied as an inert gas, cutting off the optical windows 23, the reflecting mirror 24 and the output mirror 25 from the outer side air. An opening 30 is provided on the enclosure 28 of the output mirror 25 at a position where the laser beam is to pass through. The inert gas is supplied continuously to the clean space 29 inside the enclosure 28 of the output mirror 25 so as to keep the inert gas pressure always higher than that of the outer air pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus for manufacturing a thin-film semiconductor device, and more particularly to a laser annealing apparatus for heating a silicon film formed on an insulating substrate.

[0002]

2. Description of the Related Art In a liquid crystal display device or the like, a TFT (Thin) in which a silicon film formed on an insulating substrate such as glass is polycrystallized and the polycrystallized silicon film is formed as an active layer.
Film Transistor) has been experimentally used as a liquid crystal drive element and its peripheral circuit elements. An excimer laser annealing method is used on a trial basis as one method for polycrystallizing the silicon film. In this laser annealing method, an amorphous silicon film formed on a glass substrate is irradiated with excimer laser light to be heated, melted, cooled, and recrystallized.
In addition to being able to process at a low temperature of less than 10 degrees Celsius, inexpensive non-alkali glass can be used as a glass substrate,
The performance of the device can be improved.

As shown in FIG. 2, a laser annealing apparatus used for such a process (for example, Japanese Patent Application Laid-Open No. 8-316169) has a laser oscillator 1 for generating an excimer laser and a laser beam emitted from the laser oscillator 1. A beam shaper 2 for shaping a laser beam, an airtight chamber 3 for introducing the laser beam shaped by the beam shaper into the inside, and a substrate 4 to be processed placed on the surface of the chamber 3 The laser oscillator 1 includes a laser tube 6 filled with a luminescent gas, an optical window 7 provided at both ends of the laser tube, and a resonance tube provided at both ends of the laser tube. A device mirror 8 is provided, and outside air in a clean room is introduced into a main body cover 9 which covers them.

[0004]

However, at a manufacturing site of a thin film semiconductor device, ammonia, sulfur, moisture, etc. emitted by an operator are scattered in a vapor state in the outside air, and furthermore, a variety of types used in the manufacturing process are used. A variety of chemicals are also being atomized in vapor form. Therefore, these chemical substances adhere to the optical window 7 of the laser oscillator 1 and the surface of the resonator mirror 8, and the product gradually adheres only to a portion irradiated with the laser light by some photo-CVD reaction. When such "white stain" adheres, the transmittance and reflectivity of the laser beam are reduced, and this has been a factor of variation in the production of the thin film semiconductor device. These "white stains"
Is composed of ammonium sulfate caused by ammonia or the like emitted from the human body, silicon oxide or low molecular siloxane caused by a chemical (silicon-based adhesive or the like) used in manufacturing a thin film semiconductor layer.

Usually, cleaning is performed several times a month to remove the dirt. However, since the production line is stopped every time cleaning is performed, there is a drawback that the actual operation time of the apparatus is shortened. .

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has a laser oscillator, a beam shaper, a chamber for introducing laser light through a transmission window, and a substrate to be processed in the chamber. In a laser annealing apparatus comprising a mounting table for fixing and moving, an optical window and a resonator mirror in the laser oscillator are covered with a cover,
The main point is to make it possible to introduce an inert gas into the cover and to shut it off from the causal environment.

According to the present invention, the optical system through which the laser beam passes is completely shielded from the outside air, whereby the occurrence of the photo-CVD reaction can be prevented.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail. FIG. 1 is a view schematically showing a laser annealing apparatus according to the present invention. In the figure, a laser annealing apparatus includes a laser oscillator 11 for generating a pulse laser.
A beam shaper 12 for shaping a laser beam mainly emitted from a laser oscillator; an airtight chamber 13 for introducing the laser beam shaped by the beam shaper into the inside; A mounting table 15 on which a substrate to be processed 14 is mounted, a transmission window 17 provided in a part of the chamber 13 above the mounting table 15 and transmitting a laser beam 16;
A cover 18 covers a path of laser light between the laser oscillator 11 and the beam shaper 12 and a cover 19 covers a path of laser light between the beam shaper 12 and the chamber 13.

Here, the mounting table 5 is fixed to a mounting table driving mechanism movable in the X and Y directions, and further includes a heater for preheating the installed glass substrate to about 400 degrees. The chamber 13 is formed of a sturdy housing such as stainless steel, and has a gas supply / exhaust mechanism for evacuating the inside to a vacuum and introducing an inert gas such as nitrogen into the inside. The chamber 13 is connected to a transfer mechanism for placing the substrate to be processed 14 placed on the outside on the mounting table 15 therein and discharging the processed substrate 14 to the outside. The transmission window 17 is provided on the substrate 14
And is disposed at a portion facing the chamber 13.
In addition, it functions as a partition for keeping the inside of the chamber airtight. The transmission window 17 itself is 40 cm long x 20 cm wide
× Made of quartz glass with a thickness of about 1 cm.

Further, the laser oscillator 11 is entirely covered by a main body cover 20. Inside the laser oscillator 11, a laser tube 21 filled with a luminescent gas, a pair of discharge electrodes 22 installed inside the laser tube 21, and a laser tube An optical window 23 installed at both ends of the laser tube 21 for keeping the inside of the laser tube 21 airtight, and a resonator mirror including a reflecting mirror 24 and an output mirror 25 provided further outside the optical window 23 are installed. Reference numeral 26 denotes a shutter provided on the main body.

A laser gas composed of a halogen gas and a diluent gas is supplied into a laser tube 21 from a gas supply system (not shown). The laser gas is discharged by a discharge electrode 22 to emit light. The light is amplified by being reciprocated in the resonator with the output mirror 25 and is output to the beam shaper 12 as pulsed excimer laser light 27. When outputting, the shutter 26 is opened.

For example, when xenon and neon are used as the rare gas and HCl is used as the halogen gas, the oscillation wavelength is 30.
An 8 nm excimer laser 27 is generated. The generated laser light has a rectangular shape with a high energy intensity of about 2 × 3 cm in the vicinity of the center, which is formed by the beam shaper 12 to have a short side of 0.4 to 1.0 mm and a long side of 10 to 30 cm.
The laser beam 16 is processed into a long and narrow linear laser beam 16 having a flat intensity distribution. The laser beam 16 is linearly formed by, for example, 3
This is because uniform processing is performed on a large glass substrate as large as 0 × 60 cm.

Thus, the optical window 2 inside the laser oscillator 11
3, the reflecting mirror 24 and the output mirror 25 are covered with a cover 28 made of a strong stainless steel casing, for example.
8 forms a static chamber 29 integrally with the laser tube 21.
N 2 gas is supplied into the interior of the static chamber 29 from a supply / exhaust mechanism (not shown) as an inert gas.
And the output mirror 25 are shielded from the outside air. The cover 28 on the output mirror 25 side has an opening 3 at a place where the laser beam 27 passes.
0 is provided, and the inert gas is continuously supplied to at least the inside of the cover 28 on the output mirror 25 side so that the pressure is always higher than the outside pressure. Furthermore, the main body cover 20
The inside is supplied with air from which ammonia, sulfur and the like have been removed through a chemical filter 31.

According to the present invention, since the optical window 23, the reflecting mirror 24 and the output mirror 25 constituting the optical system are shielded from the outside air, it is possible to prevent the photo-CVD reaction from occurring. Further, a chemical filter 3 is provided inside the main body cover 20.
By sending chemically clean air through 1, the above-mentioned photo-CVD reaction can be further prevented. As a result, the cleaning of the optical system was conventionally required about several times a month, but the cleaning cycle can be extended to about five times that of the related art by the present invention.

[0015]

As is apparent from the above description, the present invention can reduce the number of cleanings of the optical system of the laser oscillator 21, thereby greatly extending the actual operation time of the apparatus.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a laser annealing apparatus of the present invention.

FIG. 2 is a diagram showing a schematic configuration of a conventional laser annealing apparatus.

[Explanation of symbols]

 Reference Signs List 11 laser oscillator 12 beam shaper 13 chamber 15 mounting table 21 laser tube 23 optical window 24 resonator mirror reflecting mirror 25 resonator mirror output mirror 27 laser light 28 cover 29 static chamber 31 chemical filter

Claims (2)

[Claims] A laser beam is generated from a laser oscillator having an optical window and a resonator mirror provided at both ends of a laser tube, and the laser beam emitted from the laser oscillator is shaped by a beam shaper. In a laser annealing apparatus that irradiates a substrate to be processed set in a chamber, a cover covering the optical window and the resonator mirror is provided at both ends of the laser oscillator, and an inert gas can be supplied into the cover. A laser annealing apparatus characterized in that: 2. The laser annealing apparatus according to claim 1, wherein the laser oscillator and the resonator mirror are installed in a main body cover, and a chemical filter is installed in an air supply mechanism in the main body cover.