JPH0754857B2 - Gas laser device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas laser device such as an excimer laser.

2. Description of the Related Art In an apparatus using a laser as a light source, for example, an excimer laser stepper, it is very important to maintain a high operating rate of the laser.

On the other hand, conventionally, when the laser has to be stopped due to maintenance or failure of the laser, maintainability and repairability are improved to shorten the stop time.

If possible, a replacement laser device is prepared and light is supplied from the replacement laser device during the stop time.

Problems to be Solved by the Invention In a gas laser device such as an excimer laser, which has low reliability for long-term operation and requires frequent maintenance, stopping the laser for maintenance or repair is an important problem. The stop time varies depending on the situation, and even if the repairability is improved, the stop may be required for a long time due to a failure.

Further, when the replacement laser device is used, in the conventional laser device, the laser head for generating the laser medium by the discharge and the laser resonator are integrally supported. Each time it is necessary to adjust the optical system, it takes a long time for the precision optical system, and when the replacement laser device is not moved to another position without moving the stop laser, the performance of the entire device is not May be damaged.

Means and Actions for Solving Problems The present invention has been conceived in view of the above, and when the laser head is stopped, the laser head for replacement can be promptly replaced and the operation can be continued. It is intended to provide a gas laser device that can significantly reduce the decrease in operating rate due to the stop of the laser device of the device using, and that does not impair the performance of the entire device by replacing the laser device. The configuration is such that a fixed laser resonator includes windows at both ends in the optical axis direction, and the laser head for gas excitation by discharge can be moved in a direction perpendicular to the optical axis. A plurality of laser heads can be exchanged and used for the laser resonator.

Embodiment An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an excimer laser stepper showing a usage example of a gas laser device. In FIG. 1, reference numeral 1 is an excimer laser device for generating an excimer laser beam, and this excimer laser device 1 determines the optical axis of the laser beam. A laser resonator 2 and a laser head (discharge tube) 3 for generating a laser medium by electric discharge are independently supported by a machine frame 4.
The laser head 3 is detachably attached to the machine frame 4 in a direction perpendicular to the optical axis.

The laser resonator 2 is composed of an etalon 5 and a rear mirror 6 located below the laser head 3, and a front mirror 7 located above. The laser medium excited by the laser head 3 is located at both ends of the laser head 3 in the optical axis direction. Window
The mirrors 6 and 7 of the laser resonator 2 are resonated through the laser beams 3a and 3b to be extracted as laser light.

In this embodiment, an example in which an etalon is installed as an example of the laser resonator 2 is shown, but a plurality of etalons and gratings may be installed as wavelength selecting elements, or a combination of these may be installed.

The laser light is reflected by the mirror 8, the integrator 9, the mirror 10, the condenser lens 11, the reticle 12, and the projection lens.
The image is projected onto the wafer 14 via 13.

The relationship between the laser head 3 and the machine casing 4 is as shown in FIGS. The laser heads 3 are placed on the free-standing tables 15, 15a, 15b, and the laser heads 3 can be set or taken out on the optical axis by moving the tables 15, 15a, 15b by rotation or sliding. I'm running. The tables 15, 15a and 15b are insulated from vibrations and the like. Although not shown in the drawing, an accessory device such as a power source or a gas circulating device is switchably connected to each of the laser heads 3.

In the above configuration, when the laser head 3 set on the optical axis must be stopped, the bases 15, 15a, 15b are rotated or slid to move the laser head 3 on the optical axis to the outside of the machine frame 4. The laser head 3 is moved, and another laser head 3 is set on the optical axis to operate this laser head 3. As a result, the operation is restarted after a short rest time.

In the above embodiment, an example in which two laser heads 3 are prepared in one laser device and one of them is used as a spare is shown. However, for a plurality of laser devices, one spare laser head is used. May be. The gas laser device is not limited to the vertical type, but may be a horizontal type.

EFFECTS OF THE INVENTION According to the present invention, when the operating laser head 3 fails and is stopped, the laser head 3 can be promptly replaced with another laser head 3 to continue the operation. For example, it is possible to significantly suppress the decrease in the operating rate due to the stop of the laser device of the working machine such as the excimer laser stepper. Further, according to the present invention, since only the laser head 3 is replaced, the laser resonator 2 does not change even when the laser apparatus is stopped and the operation is restarted, and accordingly, the adjustment of the optical system is unnecessary. Thus, the same laser light as before the replacement of the laser head 3 can be supplied, and the performance of the entire device is not impaired.

Further, by making the laser head movable in a direction substantially perpendicular to the laser resonator, the laser becomes very compact, the installation area of the laser in the clean room is small, and the cost is greatly reduced. It also facilitates window replacement and cleaning.

[Brief description of drawings]

FIG. 1 is a schematic configuration explanatory view of an excimer laser stepper using a gas laser device according to the present invention, FIG. 2, and FIG.
The drawing is a perspective view showing an embodiment of the supporting portion of the laser head. 2 is a laser resonator, 3 is a laser head, and 3a and 3b are windows.

Claims (1)

[Claims] 1. A laser head, which includes windows at both ends in the optical axis direction with respect to a fixed laser resonator, and which is gas-excited by discharge is movable in a direction substantially perpendicular to the optical axis. Characteristic gas laser device.