JP4148489B2 - Ultraviolet laser device and method for manufacturing electrode of ultraviolet laser device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultraviolet laser device that oscillates a pulsed laser by exciting the ultraviolet laser gas by enclosing the ultraviolet laser gas in a chamber and performing pulse oscillation in the chamber, and in particular, adding xenon gas. The present invention relates to an ultraviolet laser apparatus that improves the burst phenomenon and spike phenomenon of laser output.
[0002]
[Prior art]
Conventionally, in a semiconductor exposure apparatus using an ultraviolet laser device such as an excimer laser device as a light source, the IC chip on the semiconductor wafer is exposed by alternately repeating exposure and stage movement. A burst operation in which a continuous pulse oscillation operation in which pulses are continuously oscillated and an oscillation pause in which pulse oscillation is stopped for a predetermined time is repeated.
[0003]
The burst operation of the conventional excimer laser device has a characteristic (hereinafter referred to as “burst characteristic”) in which the energy is initially high and then gradually decreases.
[0004]
Further, at the beginning of the continuous pulse oscillation operation, there is a characteristic that relatively high energy is obtained and then the pulse energy gradually decreases (hereinafter referred to as “spike characteristic”).
[0005]
As described above, when the burst characteristic is generated in the laser output output from the excimer laser apparatus, the exposure amount varies due to the fluctuation of energy for each burst.
[0006]
In addition, if spike characteristics are generated in the laser output, the accuracy of the exposure amount is further lowered, so that there is a problem that complicated discharge voltage control must be performed.
[0007]
For this reason, a technique for improving the burst characteristics and spike characteristics by disposing a xenon gas cylinder in an excimer laser apparatus and incorporating the xenon gas into the excimer laser gas has also appeared.
[0008]
[Problems to be solved by the invention]
However, in order to newly install such a xenon gas cylinder in the excimer laser apparatus, a new pipe for supplying xenon gas from the xenon gas cylinder to the chamber is required. Therefore, facilities related to the excimer laser apparatus must be renovated. Don't be.
[0009]
Specifically, the actual operating environment of the excimer laser device is to provide the chamber part and the gas supply equipment for excimer laser separately, and bring the chamber part into the gas supply equipment for excimer laser and connect it by piping. This is because piping for such a xenon gas cylinder is required.
[0010]
In particular, when new pipes are provided, there are many problems such as a complicated operation for modifying the existing gas supply equipment for excimer lasers, resulting in high costs.
[0011]
For these reasons, when the excimer laser device is operated in a burst mode, how to efficiently eliminate the burst characteristics and spike characteristics of the laser output without any equipment modification has become an extremely important issue.
[0012]
Accordingly, the present invention provides an ultraviolet laser device that solves the above-described problems and can efficiently improve the burst characteristics and spike characteristics of laser output without refurbishing equipment when performing burst operation. Objective.
[0013]
[Means for solving the problems and effects]
In order to achieve the above object, the present invention provides a burst phenomenon and spike generated in an ultraviolet laser output in an ultraviolet laser gas enclosed in any chamber of a KrF laser, an ArF laser, an F2 laser, a Kr2 laser, or an Ar2 laser. In the ultraviolet laser device to which an amount of xenon gas is added to reduce the phenomenon, the ultraviolet laser device is provided in the chamber, and includes a pair of electrodes that generate laser light by exciting the ultraviolet laser gas by discharge. At least the cathode contains a predetermined amount of xenon gas, and the xenon gas is added to the ultraviolet laser gas by sputtering the electrode containing xenon gas in the discharge between the pair of electrodes. Features.
[0014]
In the present invention , by supplying a small amount of xenon gas by sputtering of the main discharge electrode to the ultraviolet laser gas in the chamber, the burst phenomenon and the spike phenomenon generated in the ultraviolet laser output are eliminated, so that complicated control is not involved. The output of the ultraviolet laser can be easily improved and the output can be stabilized. Moreover, it is easy for the xenon gas to be contained in the electrode, and there is no need for complicated work for modifying the existing ultraviolet laser gas supply equipment.
[0015]
Further, the present invention, the degree to ultraviolet laser gas sealed in a KrF laser or ArF laser or F2 laser or Kr2 laser or Ar2 either chamber of the laser, reducing the burst phenomenon and spike phenomenon occurring ultraviolet laser output the amount of the electrode for discharge excitation used in ultraviolet laser apparatus for adding xenon gas is irradiated with xenon ion beam, characterized in that to contain a predetermined amount of xenon gas to the electrode.
Further, the present invention reduces the burst phenomenon and the spike phenomenon generated in the ultraviolet laser output in the ultraviolet laser gas sealed in any chamber of the KrF laser, ArF laser, F2 laser, Kr2 laser, or Ar2 laser. Xenon in a plasma state is struck into an electrode for discharge excitation used in an ultraviolet laser device to which xenon gas is added in an amount, and the electrode is made to contain a predetermined amount of xenon gas.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In the embodiment described below, the present invention is applied to an excimer laser device.
[0017]
FIG. 1 is a block diagram showing a configuration of an excimer laser device using a xenon gas-containing electrode.
[0018]
The excimer laser apparatus shown in FIG. 1 contains an excimer laser gas composed of a buffer gas such as Ne, a rare gas such as Ar or Kr, or a halogen gas such as F2 in a chamber 10, and this excimer laser gas contains xenon. It is a device that performs laser pulse oscillation by being excited by discharge between electrodes.
[0019]
Here, this excimer laser device is not simply provided with a new xenon gas cylinder and the xenon gas in the xenon gas cylinder is added to the buffer gas and the halogen gas. This is characterized in that a trace amount of xenon gas is added to the buffer gas and the halogen gas by sputtering of the containing electrode. The reason why the xenon gas is contained in the electrode is to eliminate the burst phenomenon and the spike phenomenon of the laser output without any equipment modification.
[0020]
The excimer laser apparatus shown in FIG. 1 includes a chamber 10, a band narrowing unit 11, a partial transmission mirror 12, an Ar / Ne gas cylinder 13, an Ar / Ne / F2 gas cylinder 14, an Xe-containing electrode 15, and an Xe gas. The sensor 16, the gas exhaust module 17, and the gas controller 18 are included.
[0021]
The chamber 10 is an encapsulating medium that encloses an excimer laser gas in which Ne gas, Ar gas, F2 gas, and Xe gas are mixed, and the band narrowing unit 11 is a unit that narrows the emitted pulsed light. It is formed by a prism beam expander or a grating (not shown). Further, the partial transmission mirror 12 is a mirror that transmits and outputs only a part of the oscillation laser light and returns the rest into the chamber 10.
[0022]
The Ar / Ne gas cylinder 13 is a gas cylinder that stores a mixed gas of argon and neon, and the Ar / Ne / F2 gas cylinder 14 is a gas cylinder that stores a mixed gas of argon, neon, and fluorine.
[0023]
The Xe-containing electrode 15 is a pair of electrodes facing a cathode and an anode containing a predetermined amount of xenon gas. Only a cathode with a large amount of sputtering can be used as a xenon-containing electrode.
[0024]
The Xe gas sensor 16 is a gas sensor that detects the ratio of xenon gas or the like contained in the excimer laser gas sealed in the chamber 10, and the gas exhaust module 17 sends the excimer laser gas in the chamber 10 to the outside. This is an exhaust module.
[0025]
Based on the detection output of the Xe gas sensor 16, the gas controller 18 supplies Ar / Ne gas from the Ar / Ne gas cylinder 13 to the chamber 10, and Ar / Ne / F 2 from the Ar / Ne / F 2 gas cylinder 14 to the chamber 10. It is a controller that controls the supply of gas and the exhaust of gas for excimer laser by the gas exhaust module 17.
[0026]
Thus, in this excimer laser apparatus, the xenon containing electrode 15 is arrange | positioned as a main discharge electrode of the conventional excimer laser apparatus, and a trace amount xenon gas is supplied to the chamber 10 by sputtering. The Xe gas sensor 16 detects the ratio of xenon gas, and the gas controller 18 supplies Ar / Ne gas from the Ar / Ne gas cylinder 13 to the chamber 10, and Ar / Ne / F2 gas cylinder 14 supplies Ar to the chamber 10. The xenon gas ratio can be finely adjusted by adjusting the supply of / Ne / F2 gas and the exhaust of the excimer laser gas by the gas exhaust module 17.
[0027]
Next, burst characteristics and spike characteristics when an excimer laser gas to which such xenon gas is added will be described.
[0028]
FIG. 2 is a diagram illustrating an example of burst characteristics and spike characteristics when xenon gas is added to a buffer gas and a halogen gas by sputtering from a xenon-containing electrode. In this example, 10 ppm of xenon gas is added to the excimer laser gas.
[0029]
As shown in FIG. 5A, when no xenon gas is added, assuming that the initial burst energy value is 1, the energy position decreases as the number of bursts increases, and eventually 40% (0.4 ) Has a burst characteristic that converges to a degree.
[0030]
On the other hand, when 10 ppm of xenon gas is added, the number of bursts where the energy value converges is small, and the energy that decreases as the number of bursts increases is small. Furthermore, when 10 ppm of xenon gas is added, the energy value of each burst is much larger than when no xenon gas is added.
[0031]
Thus, when 10 ppm of xenon gas is added to the buffer gas and the halogen gas by sputtering from the xenon-containing electrode, the burst characteristics are greatly improved without using a xenon gas cylinder.
[0032]
Further, as shown in FIG. 5B, when xenon gas is not added, assuming that the initial pulse energy value is 1, the energy value decreases as the number of pulses increases, and eventually 40% (0 .4) It has a spike characteristic that converges to the extent. For this reason, in practice, the pulse at the spike portion until the pulse converges and the energy converges cannot be used.
[0033]
On the other hand, when 10 ppm of xenon gas is added, the spike portion is almost eliminated, the energy value converges very rapidly, and the variation in energy value is greatly improved. Each pulse energy value when 10 ppm of xenon gas is added is much larger than when no xenon gas is added.
[0034]
As described above, when 10 ppm of xenon gas is added to the buffer gas and the halogen gas by sputtering from the xenon-containing electrode, the spike characteristics are greatly improved without using a xenon gas cylinder.
[0035]
By the way, although the case where the gas for excimer laser containing halogen gas was used was shown in this Embodiment, this invention is not limited to this, Various ultraviolet lasers, such as gas for excimer laser which does not contain halogen gas It can be widely applied to devices.
[0036]
For example, KrF (248 nm), ArF (193 nm), F2 (157 nm), Kr2 (146 nm), Ar2 (126 nm), and the like are known as typical ultraviolet lasers for semiconductor exposure. Also in the case of a laser, the burst phenomenon and the spike phenomenon can be reduced by adding xenon gas.
[0037]
Next, how xenon is contained in the xenon-containing electrode 15 will be described with reference to the drawings. Here, a case where xenon is contained by ion implantation and a case where xenon is contained by high frequency discharge are shown.
[0038]
FIG. 3 is an explanatory diagram of an ion implantation apparatus for implanting xenon into the xenon-containing electrode 15 shown in FIG.
[0039]
As shown in the figure, in the ion implantation apparatus, the ion generator 30 has ionized xenon atoms. Unnecessary ion atoms are removed from the xenon ions by passing through the analysis magnet 31 for mass spectrometry. Only the selected xenon ions pass through the slit 32 and enter the accelerator 33 and are accelerated to high energy by the electric field. The high-energy xenon ion beam is scanned in the vertical and horizontal directions by the scanning magnets 34 and 35 and is injected into the substrate 36. Thus, the substrate 36 can be the xenon-containing electrode 15.
[0040]
FIG. 4 is a principle diagram of high frequency discharge as the second means.
[0041]
The xenon existing between the cathode electrode 40 and the anode electrode 41 facing each other is brought into a plasma state by the discharge between both electrodes, and the driving of the accelerated xenon 42 to the substrate 43 is utilized.
[0042]
Here, how to obtain the xenon content in the electrode will be described.
[0043]
In the following, the xenon density x (wt%) in the electrode is set, and the amount of xenon required in the gas is 10 ppm.
[0044]
The number of discharges between electrodes is Apls,
The amount of electrode sputtered at the number of interelectrode discharges Apls is y (g),
When the amount of gas injected according to the number of interelectrode discharges Apls is M (liter),
The number of moles of xenon required in the amount M of the gas to be injected is determined by the equation M * 10/10 ^ 6 * 1 / 22.4 (1). Note that “^” indicates a power.
[0045]
Further, the number of moles of xenon contained in the electrode amount y to be sputtered is determined by the equation y * x / 100 * 1 / 131.3 (2).
[0046]
Here, it is only necessary to obtain x under the condition that the expressions (1) and (2) are equal. M is determined by design, and y is known by actual measurement.
[0047]
FIG. 5 is a flowchart for explaining the control of the laser oscillation start from the state where no xenon is present in the chamber 10.
[0048]
First, the laser gas in the chamber 10 is replaced with a new gas, so that almost no xenon is present (step S1). Next, adjustment is performed so as to obtain desired performance (output power, spectrum, etc.) by performing adjustment oscillation of the laser (step S2). The electrode is sputtered by this adjustment oscillation, and xenon is added to the laser gas. Therefore, after step S3, laser oscillation can be performed in a state containing xenon gas, and operations such as semiconductor exposure processing can be performed.
[0049]
The number of adjustment oscillations B is obtained by the following equation, as in (1).
[0050]
Z * 10/10 ^ 6 * 1 / 22.4
= B * y / A * x / 100 * 1 / 1131.3
As described above, since the xenon-containing electrode 15 is disposed in the conventional excimer laser device and the xenon gas is supplied by sputtering, the following effects can be obtained.
[0051]
(1) Even without using a xenon gas cylinder, it is possible to reduce the burst phenomenon and the spike phenomenon that occur in the excimer laser output.
[0052]
(2) Excimer laser output can be easily stabilized without accompanying control related to the supply of excimer laser gas.
[0053]
(3) The excimer laser output can be stabilized using a conventional excimer laser device as a basic configuration.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an excimer laser device using a xenon gas-containing electrode.
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.
FIG. 3 is an explanatory diagram of an ion implantation apparatus for implanting xenon into a xenon-containing electrode.
FIG. 4 is a principle diagram of high frequency discharge in which xenon is injected into a xenon-containing electrode.
FIG. 5 is a flowchart illustrating control of laser oscillation start.
[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 containing electrode 16 ... Xe gas sensor 17 ... Gas exhaust module 18 ... Gas controller

Claims (3)

An xenon gas in an amount sufficient to reduce the burst phenomenon and spike phenomenon generated in the ultraviolet laser output is added to the ultraviolet laser gas sealed in any chamber of the KrF laser, ArF laser, F2 laser, Kr2 laser, or Ar2 laser. In the ultraviolet laser device to be added ,
A pair of electrodes disposed in the chamber and generating laser light by exciting the ultraviolet laser gas by discharge;
Wherein at least the cathode of the pair of electrodes contains a predetermined amount of xenon gas,
An ultraviolet laser device , wherein xenon gas is added to an ultraviolet laser gas by sputtering an electrode containing xenon gas by discharge between the pair of electrodes . An xenon gas in an amount sufficient to reduce the burst phenomenon and spike phenomenon generated in the ultraviolet laser output is added to the ultraviolet laser gas sealed in any chamber of the KrF laser, ArF laser, F2 laser, Kr2 laser, or Ar2 laser. An electrode manufacturing method for an ultraviolet laser device, comprising: irradiating a discharge excitation electrode used in an ultraviolet laser device to be added with a xenon ion beam and causing the electrode to contain a predetermined amount of xenon gas. An xenon gas in an amount sufficient to reduce the burst phenomenon and spike phenomenon generated in the ultraviolet laser output is added to the ultraviolet laser gas sealed in any chamber of the KrF laser, ArF laser, F2 laser, Kr2 laser, or Ar2 laser. An electrode manufacturing method for an ultraviolet laser device, comprising: impregnating a plasma state of xenon into a discharge excitation electrode used in an ultraviolet laser device to be added , and causing the electrode to contain a predetermined amount of xenon gas.

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