JPS63234579A - Excimer laser device - Google Patents

Abstract

PURPOSE:To eliminate the need for the exhaust of the whole medium gas in a laser chamber, and to reduce running cost by forming a first space isolating a region in the laser chamber in the vicinity of an optical element and mounting and dismantling the optical element. CONSTITUTION:Space is formed among a laser chamber 12 and optical elements 14, 16, valve means 24 capable of separating the space and space in the laser chamber 12 are set up among the laser chamber 12 and the optical elements 14, 16, and a gas discharge means 30 and a gas injection means 34 are connected respectively into space shaped by the valve means 24. Consequently, a space region in the laser chamber 12 is isolated by the valve means 24 arranged near the optical elements when the optical elements are exchanged, and a medium gas is exhausted only in space on the optical element 14, 16 sides and the medium gas in the laser chamber 12 is not exhausted. Accordingly, a mixed gas is not wasted, thus reducing running cost as an excimer laser device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an excimer laser device, and particularly to an improvement in a mirror exchange mechanism. - [Prior Art] Currently, excimer lasers are attracting attention among lasers used in optical devices and the like, and are being widely used.

This is largely due to the fact that excimer lasers are pulsed lasers excited by discharge or electron beams, and can provide high output at short wavelengths.

The medium gas used for oscillation of this excimer laser is usually a rare gas herolite, but as the laser oscillation is repeated, the medium gas gradually deteriorates. For example, in the case of discharge excitation, this is relatively often caused by arc discharge or the like.

When the laser medium gas deteriorates in this way, impurities such as fluoride are generated and adhere to the windows of the resonant mirror or external mirror, resulting in a decrease in laser output or uneven beam intensity. Ta.

The above-mentioned inconveniences are usually dealt with by replacing the mirror or window.

Furthermore, when replacing such a mirror or window, conventionally, the mixed gas inside the laser chamber has been completely exhausted before replacing the mirror or window.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, when the cycle of gas exchange in the chamber due to deterioration of scum is shorter than the cycle of gas exchange due to the adhesion of impurities on the mirror or window. , or even if the period for replacing the mirror or the like is longer, if the replacement time does not coincide with the gas replacement, the usable mixed gas will have to be exhausted wastefully.

Therefore, since the medium gas used for oscillation of the excimer laser is relatively expensive, there is a problem that the running cost becomes high.

The present invention has been made in view of these points, and aims to solve the above problems and reduce the running cost of an excimer laser device.

[Means for Solving the Problems] The excimer laser device according to the present invention forms a space between a laser chamber and an optical element, and separates the space from the space inside the laser chamber. The technical point is that a valve means capable of 1111 is provided between the laser chamber and the optical element, and a gas exhaust means and a dregs injection means are respectively connected to the space formed by the valve means. .

[Operation] In the present invention, when replacing the optical element, the spatial region within the laser chamber is separated by the valve means disposed near the optical element. At this time, a space is formed on the optical element side by the valve means.

The medium gas is exhausted only to the space on the optical element side, and the medium gas inside the laser chamber is not exhausted.

Therefore, the mixed gas is not wasted, and the running cost of the excimer laser device can be reduced.

[Example code] Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, and FIG. 2 shows a cross section of the main part of this embodiment. In addition,
The basic structure of a laser oscillator itself is well known.

In the figure, 10 is an excimer laser device main body, and 12 is a laser chamber installed inside the excimer laser device main body, which is filled with a laser medium material made of a mixed gas of halogen gas and rare gas. 14 is a high reflection mirror, 16 is an output mirror, and these two mirrors constitute a resonator.

In the apparatus configured as described above, excimer excitation is performed by discharge of the mixed gas, laser light is oscillated between the high reflection mirror 14 and the output mirror 16, and a part of the oscillated laser is transmitted to the output mirror. 16 and is emitted as a radiation output.

The high reflection mirror 14 and the output mirror 16 are respectively disposed at both ends of the laser chamber 12 while being held by mirror holders 18 .

The mirror holder 18 is fixed to both ends of the laser chamber 12 and is configured to hold each mirror by being held by mirror hold screws 20. Furthermore, an O-ring 22 is interposed at the boundary between each mirror and the mirror holder 18 to strengthen sealing performance. Furthermore, the mirror hole screw 2o can also be used for fine adjustment of the position of each mirror.

A gate valve section 24 (first space) is formed as a part of the laser chamber 12 inside the high reflection mirror 14 and output mirror 16 fixed in this way.

The gate valve section 24 is used when replacing each mirror, and is used for gas exhaust and injection ports 2 provided at the bottom of the figure.
6 is connected to an external gas pipe 28, and the gas cylinder (actually He, Kr) is connected via this gas pipe 28.
(Multiple gas cylinders with inert gas and halogen scum)
30 and a rotary pump 32 for exhausting gas. Note that it is desirable that the volume of the gate valve section 24 be as small as possible. Note that the gas cylinder 30 is He in the case of a KrF laser.

It consists of three types of gas cylinders: Kr and F.

In the middle of the gas pipe 28, there are four valves 34a.

Two gas pressure gauges 34b, 34c, and 34d are provided, respectively, so that the gas pressure inside the gate valve section 24 can be adjusted.

On the other hand, inside the gate valve section 24, a gate 38 is provided inside the valve section 24 for separating only a minute space near the mirror (preferably a laser oscillation optical path) from a main space inside the laser chamber 12. At the boundary between the gate 38 and the inner wall of the gate valve portion 24, an O-ring 22 is interposed to strengthen sealing performance, similar to the mirror portion described above.

The gate 38 is connected to a drive bar 42 via a spring 40, and is configured to be slidable in the vertical direction in the figure by the drive bar 42, and the movement of the gate 38 allows movement of the inside of the laser chamber as described above. It is designed to separate the mixed gas space.

Further, the drive bar 42 protrudes outside the laser chamber 12 and is movable in the vertical direction by a drive means (not shown).

Next, the overall operation of the above embodiment will be explained.

Laser chamber 1 filled with mixed gas (about 3 gases)
When the gas is excited by a high voltage discharge in the laser beam 2, laser oscillation occurs between the high reflection mirror 14 and the output mirror 16, and part of the laser light passes through the output mirror 16 and is radiated out. .

During such laser oscillation operation, the drive bar 42 is moved upward in the figure, and the gate 38 is also moved upward so that the laser oscillation is not obstructed. Moreover, all four valves 34a to j4d are in a closed state.

At this time, the gas gradually deteriorates as the laser oscillations are repeated. As a result, impurities such as fluoride are generated and adhere to the high reflection mirror 14 and the output mirror 16.

This may result in reduced laser power or non-uniform beam intensity, requiring replacement or cleaning of the mirror.

When such a state occurs, the drive bar 42 is first driven downward. Then, the cage 38 slides downward via the spring 40, and the state shown in FIG.
That is, the gate valve section 24 is closed to the laser chamber 12, and the gate valve section 24 is separated from the laser chamber 12.

Next, open the valves 34a, 34b and 34c to
- The scum in the reactor tube 24 is exhausted through the gas pipe 28 by the rotary pump 32.

At this time, the pressure inside the laser chamber 12 is applied to the gate 38, and the gate 38 is pressed against the gate valve portion 24 side.

Then, after closing the post-exhaust valve 34c, the valve 34c is closed.
d, inject an inert gas such as helium gas into the gas cylinder at 30 until the pressure is equal to atmospheric pressure, and then close valve 3.
Close 4d. After this, the high reflection mirror 14 and the output mirror 16 are each replaced.

After replacing each of the mirrors described above, the valve 34d is opened again to replace the atmosphere inside the gate valve section 24 with inert gas such as helium gas, and the inert gas is transferred to the remaining parts of the laser chamber 12 and the Inject the gas so that it is equal to the pressure of the mixed gas in space 2. At this time, the manure is injected while checking the pressure inside the cat valve part 24 using the scum pressure gauge 36.

Next, when the injection of gas into the gate valve section 24 is completed and the differential pressure applied to the gate 38 is reduced, the valve 3
4a and 34b are closed, and the drive bar 42 is now driven upwards. Accordingly, the gate 38 is slid upward via the spring 40, and the separation state between the gate valve section 24 and the laser chamber 12 is released.

Furthermore, after adjusting the optical axis and injecting rare gas and halogen gas as appropriate by adjusting the valves 34a and 34b, depending on the output state of the laser, laser oscillation is restarted.

Note that when using an external mirror, the optical axis must be precisely adjusted because the window (not shown) of the laser chamber 12 is made of quartz fluorite, MgF2 material, or these materials coated with an anti-reflection film. It doesn't have to be.

On the other hand, when replacing all the gas in the laser chamber 12, the gate valve part 24 is removed in the same way as when replacing the mirror, except that the laser chamber 12 and the gate valve part 24 are separated from each other. gas exhaust installed in
It is also possible to perform the injection through the injection port 26.

As described above, on the wood flow side, the laser chamber 12
The gate valve part 24 is separated from the gate valve part 24.
Since the high reflection mirror 14 and the output mirror 16 are replaced by exhausting only the dregs inside the laser chamber 12, there is no need to exhaust all the gas inside the laser chamber 12, which has the advantage of reducing running costs.

Note that the present invention is not limited to the above embodiments,
Needless to say, the present invention can be applied to replacing the window section when an external mirror is used, and various design changes can be made to perform the outward-looking function.

[Effects of the Invention] As described above, according to the present invention, since the first space is provided to isolate the inner region of the laser chamber near the optical element and the optical element is attached and detached, all the medium gas inside the laser chamber is removed. There is no need to exhaust the air, which has the effect of reducing running costs.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, and FIG. 2 is a sectional view showing the main parts of the embodiment. [Description of symbols of main parts] 12... Laser chamber, 14... High reflection mirror,
16... Output mirror, 24... Kate valve part, 2
8... Gas pipe, 30... To gas cylinder, 32... Rotary pump, 38... Gate, 4o... Spring, 42... Drive bar

Claims (1)

[Claims] An excimer comprising a laser chamber, an optical element for resonance, a gas injection means for injecting gas into the laser chamber, and a gas exhaust means for exhausting the gas inside the laser chamber. In the laser device, a first space forming a part of the inner region of the laser chamber is provided near the optical element, and a second space is formed between the first space and the second space isolated from the first space. An excimer laser device characterized in that the excimer laser device comprises a valve means for communicating and cutting off the gas between the two spaces, and the gas exhaust means and the gas injection means are respectively connected to the first space.