JPH11111640A - Laser annealing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser annealing apparatus, in which the frequency of cleaning of its transparent window is reduced by making the window movable for making the position of the incidence of the laser beam on the transparent window capable of being shifted. SOLUTION: A transparent window 7 at an upper part of an annealing chamber is made movable in the direction parallel to the width (the shorter side) of the laser beam, which has a rectangular shape. As a first step for shifting the transparent window 7, a tunnel 14 is shut off from the inside with a gate valve 17 which has been provided inside an airtight chamber 15 for keeping the chamber 15 airtight. Then, an inert gas 19 is introduced into the tunnel 14 from a gas inlet hole 18 to make the pressure in the tunnel 14 atmospheric. Next, the transparent window 7 is to be lifted up to remove from a packing 16, while the inert gas 19 is set supplying continuously, so that outer air does not enter the tunnel 14. After the transparent window 7 has been moved laterally by a distance larger than the width (the shorter side) of the laser beam 6, the transparent window 7 is pressed against the packing 16 on the outer wall 13 and is fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION

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.

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. The laser annealing apparatus used for such processing (for example, Japanese Patent Application Laid-Open No. Hei 8-316169) includes a laser oscillator for generating an excimer laser, a chamber serving as a processing chamber for an insulating substrate, and a substrate installed in the chamber for processing a substrate to be processed. And a mounting table on which the substrate is mounted. The chamber can form an airtight space so that the substrate to be processed can be shielded from the outside air. In order to introduce the laser light into the hermetic space, at least a part of the chamber is provided with a transmission window which is transparent to the laser light, and the laser light is introduced into the chamber through the transmission window and covered. Irradiation is performed on the surface of the processing substrate. For this transmission window, quartz glass or the like is usually used.

Although the inside of the chamber, which is an airtight space, is filled with a vacuum or an inert gas such as N2, when the substrate to be processed is irradiated with a laser beam, the substrate is processed before the process. The impurities adhered by any processing that may have been performed are atomized, and the atomized impurities adhere to the inner wall of the chamber and the inner surface of the transmission window. Then
Irradiation of the adhered impurities with the laser beam causes some photochemical reaction, and only the portion of the inner surface of the transmission window that is irradiated with the laser beam is stained white according to the number of processing lots. When the contamination becomes severe, the energy of the laser beam is attenuated to cause a variation in manufacturing. Therefore, in order to remove the contamination, cleaning processing is usually performed several times every month for each chamber. However, there is a drawback in that the time required for the process is required each time cleaning is performed and the time required for raising the apparatus to a stable state again after the cleaning is required, thereby reducing the actual operation time of the apparatus. Was.

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 having a mounting table for fixing and moving, the transmission window is movable so as to shift a portion through which a laser beam passes. According to the present invention, since the white spot is only the portion irradiated with the laser beam and the surrounding area is not discolored, the cleaning cycle of the entire apparatus can be greatly lengthened by shifting the dirty spot.

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 1 for generating a pulse laser,
A beam shaper 2 for shaping a laser beam mainly emitted from a laser oscillator, a confidential chamber 3 for introducing the laser beam shaped by the beam shaper into an interior, Mounting table 5 on which substrate 4 to be processed is mounted
A transmission window 7 provided in a part of the chamber 3 above the mounting table 5 and transmitting the laser light 6, a cover 8 covering a path of the laser light between the laser oscillator 1 and the beam shaper 2, and a beam shaping. And a cover 9 for covering the path of the laser light between the vessel 2 and the chamber 3. Here, the laser oscillator 1
Generates, for example, a KrF excimer laser (oscillation wavelength: 248 nm, pulse width: 25 ns) in the ultraviolet region. The generated laser light has a high energy intensity near the center, 2 × 3c
m having a rectangular shape of 0.04 to 0.1 cm on the short side and 10 to 30 cm on the long side by the beam shaper 2.
6 cm long, linear laser light 6 with flat intensity distribution
Processed into The laser beam 6 is made linear, for example, by 3
This is because uniform processing is performed on a large glass substrate as large as 0 × 60 cm. 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 3 is made 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 3 is connected to a transfer mechanism for placing the substrate 4 placed outside on a mounting table 5 inside and discharging the processed substrate 4 outside. And
The transmission window 7 is arranged at a portion of the upper part of the chamber 3 facing the substrate 4 to be processed, and functions as a partition wall for keeping the inside of the chamber airtight together with the chamber 3. Transmission window 7
It is itself made of quartz glass having a size of about 40 cm long × 20 cm wide × 1 cm thick. FIG. 2 is an enlarged view showing the vicinity of the transmission window. In the manufacturing process of the TFT-LCD device, a substrate 4 (glass substrate) on which an amorphous silicon thin film is formed is fixed on a mounting table 5 in a chamber 3 which is airtight and depressurized in a nitrogen atmosphere, and is shown in FIG. The substrate 4 is kept heated to about 400 degrees by a heater, and a linear pulse laser beam 6 shaped by the beam shaper 2 is irradiated from above through the transmission window 7 onto the surface of the substrate 4 to be processed. The energy density at this time is 200 to 500 mJ / c.
m2, and the amorphous silicon film is melted and cooled by the laser irradiation to be polycrystallized. Further, the laser irradiation is repeated in a pulsed manner at an interval of 200 to 300 pulses / s. At this time, the substrate 4 is horizontally moved by an XY drive mechanism (not shown) provided on the
0) at a speed of about 2 to 30 mm / s, and the above-mentioned pulse interval, the moving speed of the substrate 4 and the line width of the laser light 6 make the adjacent laser light 6 overlap only at the end. Irradiated intermittently. Then, the substrate 4 on which the entire substrate 4 has been subjected to the laser irradiation is discharged by the above-described transport mechanism. Thus, a feature of the present invention is that the transmission window 7 installed in the upper portion of the chamber 3 is movable in the width (short side) direction of the laser beam (reference numeral 11).
At the time of the above laser irradiation, the laser light 6 itself has no moving means, so the laser light 6 passes only through a specific portion (reference numeral 12) of the transmission window 7. The specific location 12
Is equal to the size of the beam of the laser light 6 and is sufficiently smaller (thinner) than the size of the transmission window 7 itself. Since the "white stain" described in the conventional example is generated only in the specific portion 12 of the transmission window 7 inside the chamber 3 through which the laser beam 6 passes, the transmission window 7 is formed at least on the short side of the linear beam. By displacing it more than the width, it is possible to use a transparent part that has not yet been soiled. 3 and 4
7 shows a state of the transmission window 7 when the transmission window 7 is shifted.
Referring to FIG. 3A, first, at the time of normal laser beam 6 irradiation, transmission window 7 is pressed and fixed by a mechanism (not shown) so as to close through hole 14 formed in outer wall 13 of chamber 3. As a result, the airtightness or vacuum of the airtight chamber 15 inside the chamber 3 is maintained. Reference numeral 16 denotes an annular packing for assisting the close contact between the transmission window 7 and the outer wall 13, and 17 denotes a gate valve provided on the airtight chamber 15 side of the chamber 3;
Reference numeral 8 denotes an introduction hole for the same inert gas (nitrogen gas, etc.) as the gas introduced into the hermetic chamber 15. Referring to FIG. 3B, when the transmission window 7 is shifted, first, the through hole 14 is sealed from the inside by the gate valve 17 provided on the airtight chamber 15 side, and the airtightness of the airtight chamber 15 is maintained. And gas introduction hole 1
From 8, an inert gas 19 is introduced into the through hole 14, and the inside of the through hole 14 is brought to atmospheric pressure. Referring to FIG. 3C, the transmission window 7 is moved upward by a mechanism (not shown) and lifted from the packing 16. At this time, the supply of the inert gas 19 is continued so that the atmosphere does not enter the inside of the through hole 14. Referring to FIG. 4A, the transmission window 7 is moved in the horizontal direction by a mechanism (not shown) so as to be larger than the width (short side) of the laser beam 6. Note that a mechanism in which the movement shown in FIG. 3C and the movement shown in FIG. 4A are integrated and the locus draws a loop may be used. It is assumed that the inert gas 19 is still supplied from the gas inlet 18. Referring to FIG. 4B, the transmission window 7 is again pressed against the packing 16 of the outer wall 13 and fixed. After fixing, delay the timing a little and
The supply of the inert gas 19 is stopped, and the inside of the through-hole 14 is depressurized through the introduction hole 18 in accordance with the state of the hermetic chamber 15 if, for example, a vacuum is applied. With reference to FIG.
The gate valve 17 which has been kept airtight is opened again, the airtight state by the transmission window 7 is restored, and the irradiation of the laser beam 6 is restarted. In this way, by cooperating with the gate valve provided on the airtight chamber 15 side, the transmission window 7 can be shifted while the airtightness (or degree of vacuum) of the airtight chamber 15 is maintained. This movement does not break the condition of the entire apparatus, and therefore, it is possible to continue the stable state before the movement and immediately process the next lot. Finally, such a movement of the transmission window 7 can be maintained in a stable state by moving the transmission window several times a month as in the conventional cleaning cycle. A cleaning process for the inside of the chamber 3 including the window 7 may be performed. As a result, the cleaning cycle of the chamber 3 could be extended to about five times the conventional one.

As is apparent from the above description, the present invention reduces the number of times of cleaning the transmission window 7 of the laser annealing apparatus, thereby extending the cleaning cycle of the chamber 3 and shortening the actual operation time of the apparatus. Can be extended significantly.

[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 the vicinity of a transmission window.

FIG. 3 is a diagram showing a procedure for moving a transmission window.

FIG. 4 is a diagram showing a procedure for moving a transmission window.

[Description of Signs] 1 laser oscillator 2 beam shaper 3 chamber 4 substrate to be processed 5 mounting table 6 laser beam 7 transmission window

Claims (5)

[Claims] 1. A laser oscillator for generating laser light, a beam shaper for shaping laser light emitted from the laser oscillator, a chamber for introducing the shaped laser light through a transmission window, and a chamber inside the chamber. And a mounting table for fixing and moving the substrate to be processed, wherein the laser is characterized in that the transmission window is movable so as to shift a portion where the laser light passes. Annealing equipment. 2. The laser annealing apparatus according to claim 1, wherein said chamber and said transmission window form an airtight space. 3. The substrate to be processed in the chamber is a glass substrate, and the object to be heated is a silicon thin film formed on the glass substrate.
A laser annealing apparatus as described in the above. 4. The laser annealing apparatus according to claim 1, further comprising a gate valve in the vicinity of the transmission window for maintaining airtightness in the chamber when moving the transmission window. 5. The laser annealing apparatus according to claim 4, further comprising a gas introduction hole for introducing an inert gas into a space between the transmission window and the gate valve.