JP2000294856A - Ultraviolet laser device and gas for ultraviolet laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve and stabilize a laser output by efficiently improving the burst characteristics and spike characteristics of an ultraviolet laser output in the case of executing a burst operation. SOLUTION: Xenon gas is doped from a compact Xe gas cylinder 15 to gas for an excimer laser in a chamber 10 supplied from an Ar/Ne gas cylinder 13 and an Ar/Ne/F2 gas cylinder 14, and the rate of the xenon gas is detected by an Xe gas sensor 16, and the supply of the xenon gas to be supplied from the Xe gas cylinder 15 is controlled by a gas controller 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet laser device for enclosing an ultraviolet laser gas in a chamber and performing pulse oscillation in the chamber to excite the ultraviolet laser gas to oscillate a pulse laser. More particularly, the present invention relates to an ultraviolet laser device and a gas for an ultraviolet laser in which xenon gas is added to improve a burst phenomenon and a spike phenomenon of a laser output.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor exposure apparatus using an excimer laser apparatus as a light source, exposure of an IC chip on a semiconductor wafer is performed by alternately repeating exposure and stage movement.
The ultraviolet laser apparatus performs a burst operation in which a continuous pulse oscillation operation in which laser light is continuously pulsed a predetermined number of times and an oscillation pause in which pulse oscillation is suspended for a predetermined time are repeated.

FIG. 6A is a diagram showing a relationship between energy and a burst number when a burst operation is performed by a conventional excimer laser device. As shown in FIG. In addition, there is a characteristic that the energy is initially high and the energy gradually decreases thereafter (hereinafter, referred to as "burst characteristic").

FIG. 6B is a diagram showing the relationship between the pulse and the energy in each burst. As shown in the figure, at the beginning of the continuous pulse oscillation operation, a relatively high energy is obtained, There is a characteristic that the pulse energy gradually decreases (hereinafter referred to as "spike characteristic").

As described above, when the burst operation using the conventional excimer laser device is performed, the burst characteristic and the spike characteristic usually occur.

[0006]

However, if burst characteristics occur in the laser output output from the excimer laser device, there arises a problem that variations in the amount of exposure due to fluctuations in energy for each burst occur.

Further, if the spike characteristic occurs in the laser output, the accuracy of the exposure amount is further reduced, so that there is a problem that complicated discharge voltage control must be performed.

That is, conventionally, the discharge voltage (charge voltage) of the first pulse of the continuous pulse oscillation in the burst mode is reduced, and the discharge voltage of the subsequent pulses is gradually increased. Since measures were taken to prevent the initial energy rise due to the spike phenomenon by changing each pulse, complicated discharge voltage control was required.

[0009] From these facts, it has been an extremely important issue how to efficiently eliminate the burst characteristics and spike characteristics of the laser output when performing the burst operation of the ultraviolet laser device.

Note that "IEEE JOURNAL OF ERECTRONICS, VO
L31, NO.12, DECEMBER 1995 p2195-p2207 "
Transmission Properties of Spark Preionization Rad
iation in Rare-Gas Halide Laser Gas Mixes "discloses a technique of adding xenon gas into neon gas alone, but this conventional technique is a technique for increasing the spark preliminary ionization intensity only, It is not to eliminate the burst characteristics and spike characteristics of the ultraviolet laser output.

Therefore, in the present invention, the above problems are solved, and when performing a burst operation, the burst characteristics and spike characteristics of the ultraviolet laser output are efficiently improved, and the laser output is improved and stabilized. The purpose is to be able to.

[0012]

In order to achieve the above object, the invention according to the first aspect of the present invention is directed to a method of sealing an ultraviolet laser gas in a chamber and performing a pulse discharge in the chamber. In an ultraviolet laser apparatus that excites a laser gas and oscillates a pulse laser, a predetermined amount of xenon gas having a predetermined concentration is supplied to the ultraviolet laser gas in the chamber, and a burst phenomenon and a spike phenomenon that occur in the ultraviolet laser output are reduced. It is characterized by reduction.

As described above, according to the first aspect of the invention, a predetermined amount of xenon gas having a predetermined concentration is supplied to the ultraviolet laser gas in the chamber to eliminate a burst phenomenon and a spike phenomenon occurring in the ultraviolet laser output. Easily increase the UV laser output without complicated control,
Further, the output can be stabilized.

The invention according to claim 2 is a xenon gas cylinder filled with xenon gas to be supplied into the chamber, and a detecting means for detecting the concentration of xenon gas added to the ultraviolet laser gas in the chamber. And control means for controlling the supply amount of xenon gas sealed in the xenon gas cylinder to the chamber based on the concentration of xenon gas detected by the detection means.

Thus, in the invention according to claim 2, the concentration of xenon gas added to the ultraviolet laser gas in the chamber is detected, and the xenon gas sealed in the xenon gas cylinder is detected based on the detected xenon gas concentration. Since the supply amount of gas to the chamber is controlled, simply providing a xenon gas cylinder, detection means and control means in the conventional ultraviolet laser device can easily improve the ultraviolet laser output and stabilize the output. Can be.

According to a third aspect of the present invention, there is provided an ultraviolet laser gas used in an ultraviolet laser device for oscillating a pulse laser by exciting an ultraviolet laser gas sealed in a chamber, wherein the ultraviolet laser gas is used. Is characterized by containing at least a predetermined concentration of xenon gas.

Thus, in the invention according to claim 3,
Since the ultraviolet laser gas is configured to contain at least a predetermined concentration of xenon gas in addition to the halogen gas, simply supplying this ultraviolet laser gas into the chamber can easily improve the ultraviolet laser output and increase the output. Can be stabilized.

Further, the invention according to claim 4 is characterized in that the ultraviolet laser gas contains xenon gas of 200 ppm or less.

The invention according to claim 5 is characterized in that xenon gas adsorbing means for adsorbing xenon gas to the chamber where xenon gas is not adsorbed on the inner wall surface, and xenon gas adsorbing on the inner wall surface of the chamber by the xenon gas adsorbing means. Means for adsorbing the xenon gas in the chamber and confirming that the concentration of the xenon gas in the chamber reaches the predetermined concentration when a sufficient amount of xenon gas is supplied such that the concentration of the xenon gas in the chamber becomes a predetermined concentration. It is characterized by having.

According to the fifth aspect of the present invention, a chamber in which xenon gas is not adsorbed on the inner wall surface, such as a chamber newly manufactured and assembled or reassembled after maintenance processing such as disassembly and cleaning after use as a laser, When using, a sufficient xenon gas is previously adsorbed on the inner wall surface of the chamber. Subsequently, when an amount of xenon gas is supplied into the chamber in a predetermined concentration, the xenon gas is added to the laser gas without being adsorbed on the inner wall surface of the chamber. For this reason, the concentration of the xenon gas in the chamber becomes a predetermined concentration. As a result, even when a newly assembled or reassembled chamber is used, the concentration of xenon gas reaches a predetermined concentration in the initial stage of use, and when a burst operation is performed, a burst phenomenon and a spike generated in the ultraviolet laser output are performed. The phenomenon can be reduced.

According to a sixth aspect of the present invention, the predetermined concentration of xenon gas in the chamber exceeds 0 ppm,
It is characterized by being at most 200 ppm.

According to a seventh aspect of the present invention, the xenon gas adsorbing means includes a xenon gas supply means for supplying xenon gas into the chamber, and the confirming means controls the xenon gas concentration in the chamber. A xenon gas supply means for supplying xenon gas into the chamber by the xenon gas supply means, and when the xenon gas concentration in the chamber measured by the concentration measurement means reaches a predetermined concentration, The xenon gas supply by the xenon gas supply means is stopped.

According to the seventh aspect of the invention, the xenon gas is supplied in advance into the chamber where the xenon gas is not adsorbed on the inner wall surface. The concentration of the xenon gas in the chamber is measured, and when the concentration of the xenon gas reaches a predetermined concentration, the supply of the xenon gas into the chamber is stopped. Subsequently, when an amount of xenon gas is supplied into the chamber so as to have a predetermined concentration, the xenon gas is added to the laser gas without being adsorbed on the inner wall surface of the chamber. For this reason, the concentration of the xenon gas in the chamber becomes a predetermined concentration. As a result, even when a newly assembled or reassembled chamber is used, the concentration of xenon gas reaches a predetermined concentration in the initial stage of use, and when a burst operation is performed, a burst phenomenon and a spike generated in the ultraviolet laser output are performed. The phenomenon can be reduced.

Further, in the invention according to claim 8, the xenon gas adsorbing means includes xenon gas supply means for supplying xenon gas into the chamber, and the confirming means determines a laser energy value at the time of laser pulse oscillation. A laser pulse oscillation is performed by supplying xenon gas into the chamber by the xenon gas supply unit and measuring a laser energy value before and after a predetermined number of pulse oscillations measured by the energy measurement unit. The xenon gas supply by the xenon gas supply means is stopped when the measured laser energy value after a predetermined number of pulse oscillations does not decrease.

In the invention according to claim 8, the xenon gas is supplied in advance into the chamber in which the xenon gas is not adsorbed on the inner wall surface. When laser pulse oscillation is performed and supply of xenon gas into the chamber is stopped when the measurement device detects that the energy value of the laser at the predetermined number of pulses has not decreased. Subsequently, when an amount of xenon gas is supplied into the chamber so as to have a predetermined concentration, the xenon gas is added to the laser gas without being adsorbed on the inner wall surface of the chamber. For this reason, the concentration of the xenon gas in the chamber becomes a predetermined concentration. As a result, even if a newly assembled or reassembled chamber is used, when the xenon gas concentration reaches a predetermined concentration in the initial stage of use and burst operation is performed,
Burst and spike phenomena occurring in the ultraviolet laser output can be reduced. According to the invention of claim 8, the concentration can be accurately measured without providing a xenon gas concentration detecting device.

According to a ninth aspect of the present invention, the xenon gas adsorbing means includes xenon gas supply means for supplying xenon gas into the chamber, and the confirming means measures a discharge voltage value during laser pulse oscillation. Xenon gas is supplied into the chamber by the xenon gas supply unit to perform laser pulse oscillation, and a discharge voltage value before and after a predetermined number of pulse oscillations measured by the voltage measurement unit is measured. The supply of xenon gas by the xenon gas supply means is stopped when the discharge voltage value after the predetermined number of pulse oscillations does not increase.

In the invention according to the ninth aspect, the xenon gas is supplied in advance into the chamber where the xenon gas is not adsorbed on the inner wall surface. Laser pulse oscillation is performed so that the laser output light energy is constant, and the supply of xenon gas into the chamber is stopped when the measurement device detects that the discharge voltage value has not increased for a predetermined number of pulses. Is done. Subsequently, when an amount of xenon gas is supplied into the chamber so as to have a predetermined concentration, the xenon gas is added to the laser gas without being adsorbed on the inner wall surface of the chamber. For this reason, the concentration of the xenon gas in the chamber becomes a predetermined concentration. As a result, even when a newly assembled or reassembled chamber is used, the concentration of xenon gas reaches a predetermined concentration in the initial stage of use, and when a burst operation is performed, a burst phenomenon and a spike generated in the ultraviolet laser output are performed. The phenomenon can be reduced. According to the ninth aspect, it is possible to accurately measure the concentration without providing a xenon gas concentration detection device.

According to a tenth aspect of the present invention, the xenon gas adsorbing means includes flashing means for flushing the inside of the chamber with xenon gas, and the confirming means supplies a predetermined amount of xenon gas into the chamber. Measuring means for measuring the concentration of xenon gas in the chamber, the concentration of xenon gas in the chamber measured by the measuring means when a predetermined amount of xenon gas is supplied by the supplying means. The method is characterized in that the flushing by the flushing means is repeatedly performed until a predetermined concentration is reached.

According to the tenth aspect, the inside of the chamber where the xenon gas is not adsorbed on the inner wall surface is flushed with the xenon gas. Thereafter, a quantity of xenon gas is supplied into the chamber so as to have a predetermined concentration. If the xenon gas concentration in the chamber does not reach the predetermined concentration, the xenon gas flushing is repeated. Flushing ends when the concentration of xenon gas in the chamber reaches a predetermined concentration. For this reason, the concentration of the xenon gas in the chamber becomes a predetermined concentration. As a result,
Even if a newly assembled or reassembled chamber is used, the concentration of xenon gas reaches a predetermined concentration in the initial stage of use, and when a burst operation is performed, the burst phenomenon and spike phenomenon occurring in the ultraviolet laser output are reduced. can do. If xenon gas having a high concentration flows during flushing, the time required for adsorbing xenon gas on the inner wall surface of the chamber can be reduced.

The invention according to claim 11 is characterized in that flushing by the flushing means is performed during or before or after the passivation process of the ultraviolet laser gas on the inner wall surface of the chamber.

[0031]

Embodiments of the present invention will be described below with reference to the drawings. The first embodiment described below shows a case where the present invention is applied to an excimer laser device, and the second embodiment shows a case where the present invention is applied to an F2 laser or the like.

(First Embodiment) FIG. 1 is a block diagram showing a configuration of an excimer laser device used in the first embodiment.

In the excimer laser apparatus shown in FIG. 1, a buffer gas such as Ne, a rare gas such as Ar or Kr, a halogen gas such as F 2, and xenon (X
e) An apparatus for sealing a gas for an excimer laser made of a gas and exciting the excimer laser gas by discharge between discharge electrodes to perform laser pulse oscillation.

Here, this excimer laser device is different from the conventional one in that a buffer gas, a rare gas and a halogen gas alone are not used to form an excimer laser gas, but a xenon gas is added to the excimer laser gas. It has that characteristic. The reason for adding such xenon gas to the excimer laser gas is to eliminate the burst phenomenon and the spike phenomenon occurring in the excimer laser output.

The excimer laser device shown in FIG. 1 includes a chamber 10, a band narrowing unit 11, and a partially transmitting mirror 1
2, Ar / Ne gas cylinder 13 and Ar / Ne / F2
It includes a gas cylinder 14, a Xe gas cylinder 15, a Xe gas sensor 16, a gas exhaust module 17, and a gas controller 18.

The chamber 10 contains Ne gas, Ar gas, and F gas.
The narrowing unit 11 is a unit for narrowing the band of the emitted pulse light, and is formed by a prism beam expander or a grating (not shown). Is done. The partially transmitting mirror 12 is a mirror that transmits and outputs only a part of the oscillation laser light.

The Ar / Ne gas cylinder 13 is a gas cylinder for storing a mixed gas of argon and neon.
The e / F2 gas cylinder 14 is a gas cylinder for storing a mixed gas of argon, neon and fluorine, and the Xe gas cylinder 15 is a small gas cylinder for storing xenon gas.

The Xe gas sensor 16 is a gas sensor for detecting the ratio of xenon gas and the like contained in the excimer laser gas sealed in the chamber 10. The gas exhaust module 17 is a gas sensor for the excimer laser gas in the chamber 10. This is a module that exhausts air to the outside.

The gas controller 18 controls the Ar / Ne gas cylinder 1 based on the detection output of the Xe gas sensor 16.
3 supply of Ar / Ne gas to chamber 10 from Ar / Ne
Ar / F 2 from the Ne / F2 gas cylinder 14 to the chamber 10
Supply of Ne / F2 gas, supply of xenon gas from Xe gas cylinder 15 to chamber 10, gas exhaust module 1
7 is a controller for controlling the exhaust of the gas for the excimer laser.

As described above, in this excimer laser device, a small Xe gas cylinder 15 is added to the conventional excimer laser device, the ratio of xenon gas is detected by the Xe gas sensor 16, and the gas controller 18 detects the ratio of the xenon gas from the Xe gas cylinder 15. The supply of xenon gas to be supplied to the chamber 10 is controlled.

Next, a description will be given of the burst characteristics and spike characteristics when using the gas for excimer laser added with such a xenon gas.

FIG. 2 is a diagram showing an example of burst characteristics and spike characteristics when an excimer laser gas to which xenon gas is added is used. Here, 10 ppm
Shows a case where the xenon gas is added to the excimer laser gas.

As shown in FIG. 4A, when the xenon gas is not added, assuming that the energy value of the initial burst is 1, the energy value becomes smaller as the number of bursts increases, and eventually the initial energy value becomes 40% ( It has a burst characteristic of converging to about 0.4).

On the other hand, 10 ppm of xenon gas was used.
When added, the number of bursts at which the energy value converges is small, and the energy that decreases with an increase in the number of bursts is also small. In addition, 10 pp of xenon gas
The energy value of each burst when m is added is much larger than when no xenon gas is added.

As described above, when the xenon gas is added at 10 ppm, the burst characteristics are greatly improved as compared with the case where the xenon gas is added again.

Further, as shown in FIG. 4B, when the xenon gas is not added, the energy value of the initial pulse is set to 1 and the energy value decreases as the number of pulses increases, and eventually the initial 4 It has a spike characteristic that it converges to about (0.4). For this reason, practically, the pulse in the spike portion until the pulse oscillation progresses and the energy converges cannot be used.

On the other hand, 10 ppm of xenon gas was used.
When added, the spike part is almost eliminated,
The energy values converge very quickly, and the variation (3σ) of the energy values is greatly improved. In addition, each pulse energy value when 10 ppm of xenon gas is added is much larger than that when no xenon gas is added.

As described above, when the xenon gas is added at 10 ppm, the spike characteristics are greatly improved as compared with the case where the xenon gas is not added.

Next, the correlation between the amount of xenon added to the gas for excimer laser sealed in the chamber 10 shown in FIG. 1, the energy value of the laser output, and its variation will be described.

FIG. 3 shows the amount of xenon gas added to the excimer laser gas enclosed in the chamber 10 shown in FIG.
It is a figure which shows the correlation value with the energy value of laser output, and its variation (3 (sigma)).

As shown in FIG. 5, when the xenon gas is not added, an energy value of only about 25% of the maximum output at the time of addition is obtained, but the amount of the xenon gas added is gradually increased (0 to 10 ppm). ) And its energy value increases rapidly.

Specifically, the addition amount of xenon gas is set to 0 to
When 2 ppm is added, the output energy increases rapidly,
In the range of 10 ppm, the output energy is substantially flat, and when the added amount is 10 ppm, the energy value becomes maximum. Thereafter, as the amount of added xenon gas is increased, the energy value gradually decreases.

When the amount of added xenon gas is gradually increased (0 to 10 ppm), the energy value varies (3 to 10 ppm).
When σ) decreases and the amount of xenon gas added becomes about 10 ppm, the variation in the energy value becomes minimum (about 25%). Thereafter, if the addition amount of xenon gas is continuously increased, the variation (3σ) increases.

From the viewpoint of energy efficiency and energy stability, it is most efficient to add about 10 ppm of xenon gas. However, even when about 200 ppm of xenon gas is added, the energy value and its variation are improved as compared with the case where xenon gas is not added.

Next, burst characteristics and spike characteristics when the amount of xenon added to the gas for excimer laser sealed in the chamber 10 shown in FIG. 1 will be described with reference to FIGS. 4 and 5. FIG.

FIG. 4 is a graph showing the correlation between the amount of xenon added to the gas for excimer laser and the burst characteristics.

As shown in the figure, when the xenon gas is not added (0 ppm), the number of bursts is increased.
The output light energy value gradually decreases, and a burst characteristic converging to a certain value is generated.
When 0 ppm or 100 ppm of xenon gas is added, the number of bursts until the output light energy converges in any case decreases.

When 10 ppm of xenon gas is added, the energy value is the largest, and the energy value of each burst decreases every time the amount of added xenon gas is increased. However, even when 100 ppm of xenon gas is added, the energy value of each burst is larger than when no xenon gas is added.

From these facts, basically, the burst characteristics are improved by the addition of xenon gas, and the burst characteristics are improved by about 10 pp.
It can be seen that the addition amount of m is the most efficient.

FIG. 5 is a diagram showing the correlation between the amount of xenon added to the excimer laser gas and the spike characteristics.

As shown in the figure, when xenon gas is not added (0 ppm), a spike characteristic in which the energy value gradually decreases until the number of pulses exceeds a predetermined number is obtained, but 10 ppm, 20 ppm, 50 ppm or 100 p.
When the xenon gas of pm is added, the spike characteristics are greatly improved in any case.

When 10 ppm of xenon gas is added, the energy value is the largest, and the pulse energy value decreases every time the amount of added xenon gas is increased. However, even when 100 ppm of xenon gas is added, the pulse energy value is larger than when no xenon gas is added.

From these facts, basically, the spike characteristics were improved by the addition of xenon gas, and the spike characteristics were improved by about 10 pp.
It can be seen that the addition amount of m is the most efficient.

As described above, in the first embodiment, a small Xe gas cylinder 15 is added to the conventional excimer laser device, and the Xe gas sensor 16 detects the ratio of xenon gas. Since the supply of xenon gas supplied from the Xe gas cylinder 15 to the chamber 10 is controlled, the following effects can be obtained.

(1) The burst phenomenon and the spike phenomenon occurring in the excimer laser output can be reduced.

(2) Excimer laser output can be easily stabilized without complicated control.

(3) The output of the excimer laser can be stabilized using the conventional excimer laser device as a basic configuration.

In the present embodiment, the Xe gas cylinder 15 and the like are added to the conventional excimer laser apparatus. However, the present invention is not limited to this, and the excimer laser gas to which xenon gas is added is used. Can be sealed in a gas cylinder, and an excimer laser gas can be directly supplied to the chamber 10 from the gas cylinder.

In this embodiment, the case where the laser pulse oscillation is performed by exciting the excimer laser gas by the discharge between the discharge electrodes has been described. However, the present invention is not limited to this. The present invention can also be applied to a case where a gas for an excimer laser is excited using a wave or the like.

The first embodiment has been described above.

(Second Embodiment) The first embodiment
In the embodiment, the case where an excimer laser gas containing a halogen gas is used is shown, but the present invention is not limited to this, and various types of ultraviolet light such as a fluorine laser and an excimer laser gas containing no halogen gas are used. It can be widely applied to laser devices.

For example, as typical ultraviolet lasers for semiconductor exposure, KrF (248 nm) and ArF (1
93 nm), F2 (157 nm), Kr2 (146 n
m) and Ar2 (126 nm) are known,
Also in the case of these ultraviolet lasers, the burst phenomenon and the spike phenomenon can be reduced by adding xenon gas.

FIG. 7 is a block diagram showing the configuration of the F2 laser device used in the second embodiment. Parts having the same functions as those of the components of the excimer laser device shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The F2 laser device shown in FIG.
This is a device in which a gas for F2 laser is sealed in 0, and this F2 laser gas is excited by discharge between discharge electrodes to perform laser pulse oscillation.

Here, this F2 laser device is characterized in that a xenon gas is added to this F2 gas, instead of forming an ultraviolet laser gas only with F2 gas as in the conventional case. The reason for adding such xenon gas to the ultraviolet laser gas is to eliminate the burst phenomenon and the spike phenomenon that occur in the ultraviolet laser output.

The F2 laser device shown in FIG.
0, the band narrowing unit 11 and the partial transmission mirror 12
, F2 gas cylinder 71, Xe gas cylinder 15, X
An e-gas sensor 16, a gas exhaust module 17, and a gas controller 72 are provided.

Here, the F2 gas cylinder 71 is a small gas cylinder storing fluorine gas forming the main component of the ultraviolet laser gas, and the gas controller 72 determines the F2 gas cylinder 7 based on the detection output of the Xe gas sensor 16.
The supply amount of the F2 gas supplied from 1 to the chamber 10 or X
The controller controls the supply amount of xenon gas from the e-gas cylinder 15 to the chamber 10.

As described above, in this F2 laser device, the small Xe gas cylinder 15 is added to the conventional F2 laser device, the ratio of xenon gas is detected by the Xe gas sensor 16, and the gas controller 72 detects the ratio of xenon gas. The supply of xenon gas to be supplied to the chamber 10 is controlled.

As a result, FIGS. 2 to 6 of the first embodiment
The result is similar to that described in
(1) Burst phenomenon and spike phenomenon occurring in F2 laser output can be reduced. (2) F2 laser output can be easily stabilized without complicated control. (3) Conventional F2 laser. This has the effect of stabilizing the F2 laser output using the device as a basic configuration.

Although the case where the present invention is applied to the F2 laser device is shown here, similar results can be obtained when the present invention is applied to an excimer laser device containing no halogen gas.

Now, consider a case where a burst operation is performed using a newly assembled or reassembled chamber.
A highly adsorptive gas such as xenon gas has not yet been adsorbed on the inner wall surface of the newly assembled or reassembled chamber. Therefore, even if xenon gas is newly supplied into the chamber so as to have a predetermined concentration, most of the supplied xenon gas is adsorbed on the inner wall surface of the chamber. For this reason, even if the concentration of the gas supplied into the chamber is measured, the xenon gas is hardly added to the laser gas, so that there is a problem that a predetermined concentration cannot be obtained. As a result, the laser output becomes unstable, and this state continues until sufficient gas is supplied into the chamber and the gas cannot be adsorbed on the inner wall surface of the chamber.

Therefore, when a newly assembled or reassembled chamber is used, the concentration of xenon gas does not reach the predetermined concentration in the initial stage of use.
In the case of the burst operation, the burst phenomenon and the spike phenomenon generated in the ultraviolet laser output could not be reduced. The embodiment described below solves the above problem by previously adsorbing xenon gas in a newly assembled or reassembled chamber.

That is, if a sufficient amount of xenon gas is previously adsorbed on the inner wall surface of the chamber, the amount of xenon gas supplied to the chamber at a predetermined concentration will not be adsorbed on the inner wall surface of the chamber. The gas has a predetermined concentration. The following description is made on the assumption of an ultraviolet laser device, particularly an ArF excimer laser in which the effect of the addition of xenon gas is remarkable.

FIG. 8 is a flowchart showing a processing procedure based on the configuration shown in FIG. However, chamber 10
Are newly assembled or reassembled. As shown in FIG. 8, the xenon gas is previously adsorbed on the inner wall surface of the chamber 10, and the concentration of the xenon gas in the chamber 10 is set to a predetermined concentration.

That is, as shown in FIG. 8, xenon gas is supplied from the Xe gas cylinder 15 into the chamber 10 where xenon gas is not adsorbed (step S8).
1). Next, the chamber 1 is detected by the Xe gas sensor 16.
The concentration of xenon gas within zero is measured. If the measured value is equal to or higher than a predetermined concentration, X
The supply of xenon gas from the e gas cylinder 15 is stopped. The predetermined concentration is 10 ppm. The same applies to the following (step S82). The xenon gas adsorption process is completed as described above.

The supply of xenon gas (step S81) will be described more specifically. The first method of supplying xenon is to supply 100% xenon gas (the xenon gas in the gas cylinder is not diluted) into the chamber 10 and then exhaust the xenon gas, and then supply 10 ppm.
A laser gas (F2, Ar, Ne mixed gas) containing xenon gas, a buffer gas (Ne or He) containing 10 ppm xenon gas, and a gas containing 10 ppm xenon gas are supplied into the chamber 10. Chamber 1
If the concentration of xenon gas within 0 reaches 10 ppm, the xenon gas adsorption process is terminated. However, when the concentration of the xenon gas in the chamber 10 has not reached 10 ppm, the gas in the chamber 10 is evacuated to 100% again.
Xenon gas is supplied into the chamber 10 and then the xenon gas is exhausted. After that, a gas containing 10 ppm xenon is supplied into the chamber 10 so that the xenon gas becomes 10 pp.
The operation of checking whether or not m has been reached is repeated.

The second method for supplying xenon is a laser gas (F 2, A 2) containing 10 ppm xenon gas as described above.
r, Ne mixed gas) or a buffer gas (Ne or He) containing 10 ppm of xenon gas, and a gas containing 10 ppm of xenon gas are supplied into the chamber 10 and exhausted while performing an operation of exhausting the same. That is, the operation is continued until the concentration becomes 10 ppm. In this case, after a gas containing 10 ppm xenon is supplied into the chamber 10, the concentration of the xenon gas is measured, and if the concentration does not reach 10 ppm, the inside of the chamber 10 is exhausted and the gas containing 10 ppm xenon is again supplied to the chamber 10. The operation of supplying the gas into the chamber 10 can be repeated until the concentration of the xenon gas in the chamber 10 reaches 10 ppm.

By performing the above processing, the chamber 1
A sufficient amount of xenon gas is adsorbed in 0, and a quantity of xenon gas supplied later corresponding to a predetermined concentration is added to the laser gas without being adsorbed on the inner wall surface of the chamber.
For this reason, the concentration of the xenon gas in the chamber becomes a predetermined concentration (10 ppm). As a result, even when a newly assembled or reassembled chamber is used, the concentration of xenon gas reaches a predetermined concentration in the initial stage of use, and when a burst operation is performed, a burst phenomenon and a spike generated in the ultraviolet laser output are performed. The phenomenon can be reduced.

Next, an embodiment in which the concentration of xenon gas can be accurately measured without using the Xe gas sensor 16 will be described.

FIG. 9 is a diagram showing spike characteristics of an ArF excimer laser. In FIG. 9A, the vertical axis indicates the energy value, and the horizontal axis indicates the number of pulses. In FIG. 9B, the vertical axis indicates the discharge voltage value, and the horizontal axis indicates the number of pulses. The region from the first pulse to the pulse a is defined as region A, and the region after the pulse a is defined as region B.

As shown in FIG. 9A, when the laser excitation intensity is constant, the energy value of the ArF excimer laser sharply decreases in the region A and then becomes a constant value and becomes stable. In the region B, the energy value does not change when the xenon gas concentration in the chamber is 10 ppm. On the other hand, when the concentration of xenon gas is 0 ppm, the energy value further decreases when the pulse a is reached,
It becomes a constant value and becomes stable.

On the other hand, as shown in FIG.
The discharge voltage value for maintaining the pulsed light energy output from the laser of the excimer laser at a constant value increases rapidly in the region A, and then becomes a constant value and becomes stable. In the region B, the discharge voltage does not change when the xenon gas concentration in the chamber is 10 ppm. On the other hand, when the xenon gas concentration is 0 ppm, the energy value further increases when the pulse a is reached, and then becomes a constant value and is stabilized.

Therefore, when the laser energy value does not decrease or the discharge voltage value does not increase at the time of the pulse a, it can be determined that the xenon gas concentration has become 10 ppm.

FIG. 10 shows a configuration of an embodiment in which xenon gas is previously adsorbed on the inner wall surface of the chamber 10 using the characteristics shown in FIGS. 9 (a) and 9 (b). FIG. 10 is a block diagram showing the configuration of the ArF excimer laser device. In addition,
Parts having the same functions as those of the components of the excimer laser device shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 10, the ArF excimer laser device is provided with a measuring device 101 for measuring an energy value or a discharge voltage value instead of the Xe gas sensor 16 in FIG. That is, the discharge voltage value of the discharge electrode in the chamber 10 or the energy value of the laser beam oscillated from the chamber 10 is measured for each pulse by the measuring device 101. The energy value or the discharge voltage value measured by the measuring device 101 is input to the gas controller.

FIG. 11 is a flowchart showing the procedure of the process performed by the gas controller 18. However, it is assumed that the chamber 10 is newly assembled or reassembled.

As shown in FIG. 11, a xenon gas adsorption process is performed. The content of this xenon gas adsorption process is S
These are indicated by 111 to S113. That is, a mixed pulse of F2, Ar, and Ne is supplied into the chamber 10 at a mixing ratio for performing actual laser oscillation, and laser pulse oscillation is performed in a burst mode (step S111), and xenon gas is adsorbed from the Xe gas cylinder 15. Xenon gas is supplied into the empty chamber 10 (step S112). Next, the measuring device 101 measures the laser energy value or the discharge voltage value. Then, at the time of the pulse a, the above processing (steps S111 to S111) is performed until it is confirmed that the laser energy value does not decrease or the discharge voltage value does not increase.
Step S113) is repeated. At the time of a pulse,
When it is confirmed that the laser energy value does not decrease or the discharge voltage value does not increase, the chamber 10
It is determined that the concentration of xenon gas in the chamber has reached 10 ppm, and the supply of xenon gas from the Xe gas cylinder 15 is stopped by the gas controller 18 (step S113). The xenon gas adsorption process ends as described above.

As another method of xenon gas adsorption treatment, first, a gas obtained by adding 10 ppm xenon gas to a mixed gas of F2, Ar, and Ne at a mixing ratio for actually performing laser oscillation into the chamber 10 (hereinafter referred to as " LG] is supplied, and the laser is pulsed.After confirming a decrease in the laser output energy value or an increase in the discharge voltage value at the a-th pulse, the gas in the chamber 10 is exhausted, and the gas LG is supplied again. It is also possible to cause the laser pulse oscillation and repeat the above processing until the decrease of the laser output energy value or the increase of the discharge voltage value is not confirmed at the a-th pulse.

When the control for keeping the discharge voltage constant is performed, a part of the laser output light is input to the photo sensor, and the change in the energy value is measured by the measuring device 101. Further, when the control for keeping the energy constant is performed, the change in the discharge voltage value is measured by the measuring device 101.

When the phenomenon shown in FIG. 9 is observed during exposure, the above-described xenon gas adsorption treatment may be performed.

As a result, even when a newly assembled or reassembled chamber 10 is used, the concentration of xenon gas reaches a predetermined concentration in the initial stage of use, and when a burst operation is performed, an ultraviolet laser output is generated. Burst phenomenon and spike phenomenon can be reduced. Further, according to the present embodiment, it is not necessary to provide the Xe gas sensor 16, so that the configuration of the apparatus can be simplified and accurate measurement of the concentration can be performed.

When a newly assembled or reassembled chamber 10 is used, impurities such as water and oxygen adhere to the inner wall surface of the chamber 10. Therefore, it is necessary to remove these impurities by so-called passivation. That is, in an ArF excimer laser, an ArF gas or a KrF gas is usually supplied into the chamber 10 to cause a chemical reaction between the impurities and the gas to remove the impurities and form a fluoride film on the inner wall surface of the chamber 10. Is done. This is called a passivation process. By the passivation process, the inner wall surface of the chamber 10 becomes stable against fluorine.

FIG. 12 is a view showing a step of passivating the inner wall surface of the chamber 10 of the ArF excimer laser using KrF gas.

As shown in FIG. 12, first, passivation processing is performed on the inner wall surface of the chamber 10 using KrF gas. Next, processing for confirming the performance of the KrF excimer laser is performed. Next, an ArF excimer laser gas is introduced into the chamber 10, and a process for confirming the performance of the ArF excimer laser is performed.

Here, the process of supplying xenon gas into the chamber 10 can be performed before the passivation process with the KrF gas as shown by the arrow S131. Further, the processing for supplying the xenon gas can be performed simultaneously with the passivation processing using the KrF gas as shown by an arrow S132. The process of supplying the xenon gas is performed by the arrow S
As shown in 133, passivation treatment with KrF gas and K
This can be performed during the process of confirming the performance of the rF excimer laser. Further, the processing for supplying the xenon gas can be performed simultaneously with the processing for confirming the performance of the KrF excimer laser as indicated by an arrow S134. Further, the process of supplying the xenon gas is performed by using KrF as indicated by an arrow S135.
It can be performed between the processing for confirming the performance of the excimer laser and the processing for confirming the performance of the ArF laser. In addition, the process of supplying the xenon gas is performed as shown in arrow S136.
This can be performed at the same time as the processing for checking the performance of the F laser.
The process of supplying the xenon gas is performed by the arrow S137.
As shown in (1), it can be performed after the processing for confirming the performance of the ArF laser.

In FIG. 12, the passivation process of the inner wall surface of the chamber 10 using KrF gas and the process of confirming the performance of the KrF excimer laser are performed. However, these processes using KrF gas may be omitted. . That is, after the passivation process of the inner wall surface of the chamber 10 is performed using the ArF gas, the performance confirmation process of the ArF excimer laser is performed.
However, in this case, the discharge electrodes and other components in the chamber 10 may be worn, and the life of the laser chamber may be shortened. Further, there is a possibility that the laser pulse oscillation becomes unstable. Therefore, it is desirable to perform the passivation process on the inner wall surface of the chamber 10 using KrF gas.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an excimer laser device used in a first embodiment.

FIG. 2 is a diagram illustrating an example of a burst characteristic and a spike characteristic when an excimer laser gas to which xenon gas is added is used.

FIG. 3 is a diagram showing a correlation between the amount of xenon gas added to an excimer laser gas sealed in the chamber shown in FIG. 1, and the laser output energy value and its variation (3σ).

FIG. 4 is a diagram showing a correlation between the amount of xenon added to an excimer laser gas and burst characteristics.

FIG. 5 is a diagram showing a correlation between the amount of xenon added to an excimer laser gas and spike characteristics.

FIG. 6 is a diagram illustrating a relationship between energy and a burst number when a burst operation is performed by a conventional excimer laser device.

FIG. 7 is a block diagram illustrating a configuration of an F2 laser device used in a second embodiment.

FIG. 8 is a flowchart showing a processing procedure based on the configuration shown in FIG. 1;

FIG. 9 is a diagram showing spike characteristics of an ArF excimer laser.

FIG. 10 shows the characteristics shown in FIGS. 9A and 9B,
1 shows a configuration of an embodiment in which xenon gas is previously adsorbed on an inner wall surface of a chamber 10.

FIG. 11 is a flowchart showing a procedure of a process performed by the gas controller 18.

FIG. 12 is a diagram showing a step of performing passivation treatment on the inner wall surface of the chamber 10 of the ArF excimer laser using KrF gas.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Chamber 11 ... Band narrowing unit 12 ... Partial transmission mirror, 13 ... Ar / Ne gas cylinder 14 ... Ar / Ne / F2 gas cylinder 15 ... Xe gas cylinder 16 ... Xe gas sensor 17 ... Gas exhaust module 18 ... Gas controller 71 ... F2 Gas cylinder 72 ... Gas controller

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Akira Sumitani 1200 Manda, Hiratsuka-shi, Kanagawa F-term (reference) 5F071 AA06 BB01 HH01 HH02 HH03 JJ04 JJ05

Claims (11)

[Claims] 1. An ultraviolet laser device for enclosing an ultraviolet laser gas in a chamber and performing a pulse discharge in the chamber to excite the ultraviolet gas and oscillate a pulse laser. An ultraviolet laser apparatus, characterized in that a predetermined amount of xenon gas having a predetermined concentration is supplied to a use gas to reduce a burst phenomenon and a spike phenomenon occurring in an ultraviolet laser output. 2. A xenon gas cylinder filled with xenon gas to be supplied into the chamber, detection means for detecting the concentration of xenon gas added to the ultraviolet laser gas in the chamber, and xenon detected by the detection means 2. The ultraviolet laser device according to claim 1, further comprising control means for controlling a supply amount of xenon gas sealed in said xenon gas cylinder to said chamber based on a gas concentration. 3. An ultraviolet laser gas used in an ultraviolet laser device for oscillating a pulse laser by exciting an ultraviolet laser gas sealed in a chamber, wherein the ultraviolet laser gas has at least a predetermined concentration of xenon. An ultraviolet laser gas containing a gas. 4. The ultraviolet laser gas according to claim 3, wherein the ultraviolet laser gas contains 200 ppm or less of xenon gas. 5. A xenon gas adsorbing means for adsorbing xenon gas in the chamber where xenon gas is not adsorbed on the inner wall surface, and xenon gas is adsorbed on the inner wall surface of the chamber by the xenon gas adsorbing means. A confirmation unit for confirming that the concentration of xenon gas in the chamber reaches the predetermined concentration when the amount of xenon gas at which the concentration of the xenon gas reaches the predetermined concentration is supplied. The ultraviolet laser device according to claim 1, wherein 6. The ultraviolet laser device according to claim 5, wherein a predetermined concentration of the xenon gas in the chamber is more than 0 ppm and 200 ppm or less. 7. The xenon gas adsorption unit includes a xenon gas supply unit that supplies xenon gas into the chamber, the confirmation unit includes a concentration measurement unit that measures the concentration of the xenon gas in the chamber, Xenon gas is supplied into the chamber by the xenon gas supply unit, and when the concentration of xenon gas in the chamber measured by the concentration measurement unit reaches a predetermined concentration, xenon gas supply by the xenon gas supply unit is performed. The ultraviolet laser device according to claim 5, wherein the supply is stopped. 8. The xenon gas adsorption unit includes a xenon gas supply unit that supplies xenon gas into the chamber, the confirmation unit includes an energy measurement unit that measures a laser energy value during laser pulse oscillation, A xenon gas is supplied into the chamber by the xenon gas supply unit to perform laser pulse oscillation, and a laser energy value before and after a predetermined number of pulse oscillations measured by the energy measurement unit is measured, and a predetermined number of pulse oscillations is performed. 6. The ultraviolet laser device according to claim 5, wherein the supply of xenon gas by said xenon gas supply means is stopped when the subsequent laser energy value does not decrease. 9. The xenon gas adsorption unit includes a xenon gas supply unit that supplies xenon gas into the chamber, the confirmation unit includes a voltage measurement unit that measures a discharge voltage value during laser pulse oscillation, Xenon gas is supplied into the chamber by xenon gas supply means to perform laser pulse oscillation, and a discharge voltage value before and after a predetermined number of pulse oscillations measured by the voltage measurement means is measured. 6. The ultraviolet laser device according to claim 5, wherein the supply of xenon gas by the xenon gas supply means is stopped when the discharge voltage value of the xenon gas no longer increases. 10. The xenon gas adsorbing means includes a flushing means for flushing the inside of the chamber with xenon gas, and the checking means includes a supply means for supplying a predetermined amount of xenon gas into the chamber, Measuring means for measuring the concentration of xenon gas, wherein, when a predetermined amount of xenon gas is supplied by the supply means, the concentration of xenon gas in the chamber measured by the measurement means reaches a predetermined concentration. The ultraviolet laser device according to claim 5, wherein flushing by the flushing means is repeatedly performed. 11. The ultraviolet laser apparatus according to claim 10, wherein the flushing unit performs flushing during, during, or after the passivation process of the ultraviolet laser gas on the inner wall surface of the chamber.