KR20010082365A - Energy stabilized gas discharge laser - Google Patents

Abstract

FIELD OF THE INVENTION The present invention relates to excimer or molecular fluorine lasers, for example KrF- or ArF-lasers or molecular fluorine (F ₂ ) lasers, in photolithographic applications, comprising gas mixtures containing small amounts of gas adducts. Equipped. The concentration of the gas adduct of the gas mixture is optimized to improve energy stability and / or overshoot control of the laser output line. The concentration is additionally determined and adjusted during laser operation depending on the impact on the output pulse energy in terms of limit and / or senescence on the new charge and / or on the discharge circuit and / or other components of the laser system. Attenuation control is provided to improve the service life of the components of the laser system by controlling the concentration of the gas adduct over time. Certain preferred xenon concentrations are at least 100 ppm to improve energy stability and / or overshoot control. The laser system will be equipped with an internal gas supply unit comprising an internal xenon gas source, or a xenon generator for supplying xenon gas from the compressed material xenon.

Description

ENERGY STABILIZED GAS DISCHARGE LASER

The term “excimer laser” refers to excimers (eg Ar ₂ ^* ), exciplexes (eg ArF ^* ) or trimers (eg Kr ₂ F ^* Is shown as a laser medium. All common features are gas discharges, in which very excited molecules are produced that do not have a stable ground state. The present invention relates to an excimer laser wherein the laser mediator comprises a halogen, in particular a fluorine-containing excited complex (eg ArF ^* and KrF ^* ). The invention also relates to a molecular fluorine (F ₂ ) laser.

In many of the scientific, medical and industrial applications of exaic and molecular gas lasers, it is important that the emitted radiation pulses have a stable (constant) energy. In gas lasers, the fact that gas discharge conditions and properties can vary greatly affects the achievement of constant energy of every pulse of emitted radiation. The characteristics and conditions of the gas discharge depend on a number of parameters that enable significant improvements to accurate reproduction through proper control. The results indicate that the energy of the emitted laser radiation pulses does not remain exactly constant at every pulse. There is a need to have an excimer or molecular fluorine laser that exhibits higher pulse-to-pulse stability.

Energy stability is indicated by various properties of the laser line in this application. One of these characteristics is the standard deviation sigma of the energy distribution of numerous laser pulses. In many applications, because the radar output is not continuous but as a burst of light, other parameters are used for stability (see background art of US Pat. No. 5,463,650, referred to in this application). In certain applications of the excimer or molecular fluorine laser line, which is optimal lithography as a light source for a wafer scanner, the energy dose stability is important (US Patent Nos. 5,140, 600 equally assigned to the assignee of the present application). (between Merced, Inc. (Cymer, Inc.)) and call more source ^TM (the source ^TM) reference to the first edition, issue (issue) 2 (summer 1999)).

Another important feature is peak-to-peak stability. In order to measure the peak-to-peak stability values, laser pulse energies are accumulated at various intervals. The absolute difference between the maximum and minimum energy associated with the average laser pulse energy is defined as the peak-to-peak stability.

Among the singularities in burst mode applications, the energy overshoot is an important feature, as shown in FIG. 1. Energy overshoot or spiking is when the laser is operated at a constant high voltage in the discharge chamber in burst mode and when the first few pulses have higher energy than the later pulses in the burst , US Pat. No. 5,710,787. The energy overshoot (designated “ovs” in FIG. 1) is defined as the difference between the energy of the first pulse in the burst and the steady state energy in the entire burst.

The quality of the gas discharge and the pulse energy of the emitted laser radiation are determined in gas discharge conditions such as external electronic circuits, characteristics and combinations and shapes of the discharge electrodes, quality and shape of pre-ionization, and the like. Depends on change and is sensitive The combination of purity of gas and the gas in the laser gas discharge chamber is very important. A small amount of impurities of a certain kind are the energy of the emitted radiation pulse, the stabilization of the energy (uniformity of energy per laser pulse from one firing to the next), the laser beam It is known that the distribution of intensity in the profile, the useful life of the laser gas and the lifetime of the individual optics and other laser components can be fatally affected. Impurities in the gas may be present in the gas mixture from an early stage, or the impurities may be present during the operation of the laser, for example in the reactive gas and laser chamber of the gas mixture (eg halogen). It may be formed through interaction between materials or by diffusion from the materials, or by reaction in the gas mixture, for example, during the operation of KrF-excimer, HF, CF ₄ , COF ₂ , SiF _4, etc. Rapid increases in concentrations of the same impurities are observed (G. M. (Ju), Jurisch et al., The effect of gas contamination on discharge-excited KrF lasers, Applied Optics, Vol. 31, No. 12, Ferrige 1975-1981 (April 20, 1992)) In stable KrF laser gas mixtures, i.e., in discharge-free operation, an increase in the concentrations of HF, O ₂ , CO ₂ and SiF _4, etc. is observed (Juri See Hi et al.).

It has been found that additional properties of the gas mixture can enhance certain characteristics of the emitted radiation. For example, US Pat. Nos. 5,307,364 and 5,982,800 (referenced by reference) suggest that small amounts of oxygen are added to the gas mixture to achieve higher reproducibility of radiation emitted during laser operation. Oxygen is not an inert gas, but the effect of oxygen on other parameters of the excimer laser, for example the uniformity of the emission intensity curve and the service life of the gas mixture, is not yet fully recognized and will be practically fatal. will be. Oxygen is particularly chemically very reactive with the atomic oxygen and ozone that can be formed in the gas discharge, and the effect on the laser gas mixture is particularly deadly during long runs. Due to the presence of oxygen, other stable impurities, for example OF ₂ and FONO, are the exa and are formed in the laser gas mixture. The impurities have a significant absorption effect on the laser radiation or pre-ionization radiation. Tests recommended in the current state of technical development in which the energy of excimer laser radiation pulses are stabilized through the addition of gases to the gas mixture have adversely affected the region and other features of emitted radiation.

Injecting a gas mixture of the correct composition into the excimer or molecular fluorine laser and maintaining the composition is known to play a role in determining important output beam parameters. For example, KrF-excimer laser gas mixtures typically consist of about 1% Kr, 0.1% F ₂ and 98.9% Ne buffers. The molecular fluorine laser typically consists of about 0.1% F ₂ and 99.9% buffer gas.

Injection of small amounts (# 0.1 Torr) of xenon in excimer and molecular fluorine laser gas mixtures is introduced to increase photopreionization output. R.S. Transmission Characteristics of Spark Pre-Ionizing Radiation in Rare-Gas Halogen Laser Mixing of RS Taylor and KELeopold, IEEE Journal of Quantum Electronics, pages 2195-2207, page 31 Vol. 12, No. 12 (December 1995). Taylor et al. Demonstrate the improvement of spark pre-ionization strength by the action of xenon added to the gas mixture. A positive result of the improvement in the preionization intensity is to improve the uniformity of the excimer laser discharge. Taylor et al. Qualitatively explain that if the concentration of xenon is too high, absorption of laser radiation occurs and attenuates the output laser line. The conclusion of Taylor et al. Is that the addition of small amounts of xenon to the excimer laser gas mixture improves the preionization strength and the discharge.

Recently, the use of xenon in ArF excimer lasers has been reported by Wakabayashi et al. Wakabayashi et al., Billion Level Sustainable ArF Excimer Lasers with High-Stable Energy, 24th Annual International Symposium on Microlithography at SPIE, Santa Clara, May 14-19, 1999. Wakabayashi et al. Describe an improvement in pre-ion intensity that results in similar results to Taylor et al., Namely increased output energy at the same input discharge voltage of an ArF-excimer laser. The optimum concentration of xenon in the ArF-excimer laser gas mixture is 10 ppm or is the peak of the output energy versus xenon concentration curve shown in FIG. 6 of Wakabayashi et al.

preference

This application is directed to US patent application Ser. No. 09 / 498,121, filed Feb. 4, 2000, 09 / 484,818, filed Jan. 18, 2000, and Provisional, filed Oct. 18, 1999. Patent Application No. 60 / 160,126, filed March 31, 1999, Patent No. 60 / 127,062, and Patent Application No. 60 / 178,620, filed Jan. 2000, which is a continuation-in-part application. Are incorporated herein by reference.

The present invention relates to gas discharge lasers, in particular pulse-to-pulse and peak-to-peak energy stabilization, energy dose stability, such as, for example, halogen-containing species, inert gases, buffer gases and xenon additives. Excimer and molecular fluorine lasers with gas mixtures that are optimal concentrations of specific component gases for improved stability and burst energy overshoot control and longer lifetime of laser system components It is about.

1 shows energy overshoot or spiking during laser operation in burst mode.

2 shows a xenon gas generator according to the present invention.

3A shows pulse-to-pulse stability for multiple bursts of 240 pulses for a conventional KrF laser system.

FIG. 3B shows the energy overshoot of a conventional burst mode operating KrF laser as a percentage of steady state output energy over the total burst, including about 240 pulses.

4A shows pulse-to-pulse energy stability for the same number of bursts of 240 pulses as FIG. 2A for a KrF laser system according to the present invention.

4b shows the energy overshoot of a burst mode operating KrF laser according to the present invention as a percentage of steady state output energy for the total bursts, including about 240 pulses.

5 shows the dependence on the xenon concentration of the energy overshoot of KrF laser operation in burst mode as a percentage of the steady state output energy of the total burst.

FIG. 6A shows the measured dependence of xenon concentration from 30 to 520 ppm of energy stability of KrF laser operation in burst mode as the inverse of percent deviation from the steady state output energy of the laser.

6B shows the measured dependence on the xenon concentration from 0 to 30 ppm of the energy stability of KrF laser operation in burst mode as a percentage of deviation from the steady state output energy of the laser.

6C shows the measured dependence of xenon concentrations from 30 to 520 ppm of the output pulse energy of the KrF laser at constant discharge voltage.

6D shows the measured dependence on the xenon concentration from 0 to 30 ppm of the output pulse energy of the KrF laser at constant discharge voltage.

FIG. 6E shows the measured dependence of output energy and energy stability sigma on xenon concentration in ArF laser gas mixture, which is presented by showing the discharge voltage required to maintain 5mJ output energy.

7 shows a preferred embodiment of KrF, ArF or F ₂ according to the invention.

In the present invention, the addition of krypton to an ArF-excimer laser gas mixture, such as a noble gas, for example xenon and its replacement, also the addition of xenon or argon to a KrF-laser, to an XeCl- or XeF-laser Advantages of the addition of argon or krypton of and addition of xenon, argon or krypton to the F ₂ -laser gas mixture are disclosed, wherein the selected concentration not only affects the photopre-ionization output and output energy, It depends on stabilization and overshoot control of the laser.

Another object of the present invention is to provide an excimer or molecular fluorine laser having a gas mixture comprising a gas adduct of an appropriate concentration which depends at least in part on the effect of the concentration of the adduct to improve the energy stability of the output laser line. To provide. The energy stability is determined based on the stabilization of the first or first few pulses after interruption of the laser operation in burst mode and the overall stabilization of the output energy of the laser.

It is another object of the present invention to provide an additional gas of an appropriate concentration based on the influence of the concentration of the adduct to improve the overshoot control of the laser.

Another object of the present invention is to provide energy attenuation control for an excimer or molecular fluorine laser to increase the service life of optical and laser tube components.

According to this object, a gas mixture containing a small amount of gas adduct for an excimer laser, for example a krF- or ArF-laser, or a molecular fluorine (F ₂ ) laser, for a high repetition rate, preferably 1 kHz. Is provided. The gas adduct is preferably xenon. For ArF-lasers, for stability reasons, the internal concentration of the gas adduct will be selected and adjusted according to one or more selected values of energy stability, overshoot control and pulse energy.

Xenon concentration selection further depends on additional criteria of output pulse energy control. For example, the pulse energy is attenuated by reducing the fluorine concentration in the gas mixture, for example to extend the laser pulse, and the loss of energy will be compensated by adding an appropriate amount of xenon to the gas mixture. . The pulse energy or energy dose will be adjusted by controlling the amount of xenon in the gas mixture.

A gas discharge laser, such as an excimer or molecular fluorine laser according to the invention, comprises a laser tube with a gas flow vessel and an electrode chamber with a pair of extended main electrodes and one or more pre-ionization electrodes. It includes. The laser tube is for example standard deviation sigma, and / or peak-to-peak, pulse-to-pulse and / or dose stability, and / or to improve burst energy overshoot control and / or characteristic energy stability. To adjust the output energy level of the laser, for example to balance energy attenuation control or the energy stability and / or overshoot control, it is filled with a gas mixture comprising a laser active gas or gases, a buffer and a small amount of additional gas. .

Preferred laser systems have an internal gas supply unit comprising a supply of additional gas, preferably a supply of xenon. An output line parameter stabilization algorithm is provided for the laser system that maintains the optimal concentration of all gas mixture compositions including halogen containing species, F ₂ , or HCl and gas adducts, preferably xenon, as well as ArF-lasers. And KrF-lasers are each provided with active rare gases Ar and Kr. Preferred gas control, composition and stabilization algorithms are described in US patent applications 09 / 379,034, 60 / 124,785, 60 / 159,525, 09 / 418,052, 09 / 317,526 and 60 / 127,062 and US patents. Algorithms disclosed in Nos. 4,393,505 and 4,977,573, each of which is assigned to the same assignee, referenced for the present invention, and disclosed in the patents and patent applications described above, control the gas adduct to the gas supply in the discharge chamber. And infusions according to the invention. Energy stability, energy dose stability, output pulse energy and drive voltage (and / or amplified spontaneous emission (ASE) and / or characteristics in the form of temperature or spatial pulses and / or total accumulated energy input into the discharge) Parameters such as bandwidth, moving average energy dose, temperature or spatial coupling, discharge width, and long and short coaxial line profiles and one or more other parameters such as divergence, time, pulse count, or a combination thereof) Monitored and the parameters and / or other parameters of the above described output line are stabilized according to the invention.

Control of the amount of gas adduct in the gas mixture is preferably used to extend the service life of the laser components. The characteristic output power range is initially set higher than the predetermined output power of the laser system within the range of the driving drive voltage. The power is then attenuated by adding gas adducts, preferably xenon or the like, to the gas mixture until the output power is reduced to a predetermined level. In the lifetime of the laser components, the amount of adduct / xenon is reduced to achieve the desired output power with each new charge.

The gas adduct will preferably be added to the gas mixture from a gas vessel comprising a premix comprising a xenon gas adduct. In addition, xenon gas may be obtained from xenon containing crystals that are heated to decompose xenon containing crystals. In this example, the xenon generator is filled with xenon-containing crystals and a heating element, and a temperature controller is used to control the xenon gas pressure.

Although xenon is the preferred gas adduct, other gas adducts may be used in accordance with the present invention. Argon can be used as a gas adduct for KrF lasers. Krypton can be used as a gas adduct for ArF lasers. Argon and / or krypton can be used as gas adducts for XeCl or XeF lasers. Argon, krypton and / or xenon can be used for the F ₂ laser. NO can be used for the XeCl laser (eg 0.1% NO in Ne). NO ₂ , N ₂ O ₄ , FONO or FNO may be used for the XeCl or F ₂ lasers.

Other elements or molecules, such as metals, for example W, or Pt, may be added to one or more metal fluoride or metal chloride species, ie preferably in WF, WF ₂ , PtF, PtF ₂ , or WF _x or PtF _x At least one is reacted to form in the gas mixture and x is preferably 3 to 16. The metals will be added to one or more electrodes of the ebionization unit or other metal component of the laser tube. Other alternative metals include chromium and aluminum. Silicon, carbon, hydrogen fluoride, ozone, mercury, hafnium, metals and alloys with high vapor pressures similar to mercury and hafnium, which are typically liquid at standard temperature and pressure (STP), will be used. Metal oxides such as oxygen and molecular bonds with one or more of chromium, fluorine or aluminum can be used and / or used as gas adducts to form halogens (i.e. fluorides, chlorides), preferably xenon Other preferred alternative elements or molecule types.

Some desired molecular bonds, either natural or ionized or natural and ionized, are added or are formed by the additional reaction of fluorine or chlorine in the gas mixture, the molecular bonds being HF, HF, CF_x(Especially CF₄), CrOF₂, CrOF, CrO₂F, CrO₂F₂, CrO₂, CrO, Cr, CrF₂, CrF, SiF₄, SiF, OF, O₂F, OF₂, Al, AlO, Al₂O, Al₂O₂, AlF, and AlF₂It includes. Also N, N₂, N_x, C, C₂, C_x, H, H₂, H_x, O, O_xAnd x is a small integer greater than or equal to 3, such as 3 to 16, and air itself is possible, as well as a combination of any of the above elements and / or molecules. Any of the above mentioned elements or molecules or bonds may be added to the gas mixture, preferably in small amounts, such as 500-1000 ppm or less or 0.1% or less, according to the invention.

In addition, one or more gas adducts may be added to the gas mixture. For example, two or more of the aforementioned additives can be added individually or in combination to control pulse energy, energy dose, energy stability and / or overshoot control. One gas adduct or combination of gas adducts will be used to control one of the above parameters, and another gas adduct or combination of gas adducts will be used to control other parameters.

A preferred embodiment of the present invention provides a laser system and a process with improved discharge uniformity and energy stability in ArF and KrF excimer lasers and F ₂ lasers. The preferred embodiments are realized in laser systems that operate the spirit of the invention and are preferably used for the control and stabilization of the pulse energy, energy stability, energy dose control and / or energy overshoot of the laser systems. Providing a gas adduct which is one of xenon and / or one of the other visible adducts described above, and associated with an excimer and / or molecular fluorine laser gas mixture.

The following invention and description, although the invention applies to continuous output laser systems, suggest controlling and / or stabilizing the parameters of the laser systems when the laser operates in a burst pattern. The present invention can be applied to other excimer lasers such as XeCl, XeF and KrCl lasers, and Ar, Kr and other aforementioned adducts would be beneficial gas adducts in other embodiments in some of the laser systems. Can be. The present invention applies to lasers operating at high repetition rates such as 1 or 2 kHz pulse repetition frequencies or higher.

A feature of the present invention disclosed below is that the computer controlled gas operations allow for optimal gas mixing and xenon partial pressure in the gas mixture to design an apparatus for enabling accurate injection of xenon into the laser gas mixture. To use gas injection and feed algorithms to maintain, use a high speed energy detector to determine and control the optimal xenon partial pressure in the gas mixture with other gas compositions such as halogen in the gas mixture. And the use of a predetermined amount of xenon as an adduct to an existing gas mixture of an excimer or molecular fluorine laser (see the referenced '034 and' 785 applications).

In a preferred embodiment of the present invention, according to a preferred method and laser system, a certain amount of xenon is added to the laser tube during a new fill to the conventional compositions of the gas mixture (see the '505 and' 573 patent and ('526 and' 785 applications). The addition of xenon to the gas mixture will affect one or more characteristics of the laser system. Thus, the specific "optimal" amount of xenon initially filled with the laser tube depends on the type of laser used and the additional result of the xenon desired. For example, at a specific operating discharge voltage, the output energy of the laser is increased or attenuated depending on the amount of xenon added to the gas mixture. Thus, energy stability and overshoot control are improved depending on the amount of xenon added. A certain amount of xenon will also be added along the balance of the effective properties of the laser system.

Argon fluoride laser

In a first embodiment of an ArF-excimer laser, in order to improve energy stability, the concentration of xenon is greater than 10 ppm and is substantially on the order of 300-500 ppm or higher. It is shown below that each of the energy stability and overshoot control is enhanced at a xenon concentration of at least 500 ppm. It is also shown below that the output energy at a specific discharge voltage has a maximum of about 10 ppm, or the required discharge voltage for generating output pulses at a specific energy (eg 5 mJ) has a minimum of about 10 ppm. However, at higher concentrations of xenon, for example at concentrations higher than 100 ppm, the energy stability and overshoot control are improved according to the invention.

The preferred xenon concentration in the first embodiment for the ArF laser is balanced by reducing the effect of xenon adducts on pulse energy at concentrations of 10 ppm or more. The upper limit for a particular laser system depends on the power supply and the limitations of the discharge circuit including the components of the pulse circuit and in particular the discharge electrodes. That is, a specific pulse energy in the range of several mJ up to 10 mJ or more is specified for a particular industrial application of the laser, and xenon may be added in an amount so large that the laser system cannot generate pulses at the specified energy. Can not.

Advantageously, in this embodiment, the energy stability and / or overshoot control is maximized and xenon concentration in the gas mixture is characterized by a specified power level, the power supply, a laser system such as pulse modules and electrodes. Adjusted according to the limitations of the components. The system components are preferably adapted to produce the desired higher output energy when no xenon is added to the gas mixture, and then xenon is added to the gas mixture to attenuate the pulse energy to the desired value. Advantageously, the pulse energy is a predetermined value and the energy stability and / or overshoot is an improved, preferably selected value. The system components are conventionally configured and the xenon is added with xenon, for example 100 ppm or more, and the drive voltage is converted into output energy at the selected value when enhancing the energy stability and / or overshoot control according to the invention. Is increased to adjust.

Krypton fluoride laser

In a third embodiment, in the case of the KrF-excimer laser, the KrF-excimer laser is intended to improve the energy stability and / or overshoot control of the output line and is a preferred gas adduct, i.e. xenon The concentration of is substantially 12 ppm or more, more preferably substantially 20 ppm or more, but substantially 2000 ppm or less, preferably substantially 600 ppm or less. In a first embodiment of the ArF laser, the upper limit of the concentration of xenon is affected by the power supply and the limits for the pulse circuit and the discharge electrode. As the development of these components takes place, the upper limit of xenon concentration can be increased. In a fourth embodiment, in the KrF laser, for the balance of the output pulse energy and the improvement of energy stability and / or the control of the overshoot due to the xenon adduct, the preferred concentration of xenon selected from the specific xenon concentration is 100 at It is in the range of 500 ppm.

As mentioned above, the resulting absorption and energy decay can significantly reduce the output energy of the laser pulses at a particular drive discharge voltage, thus helping to set a lower limit on the concentration of xenon in the gas mixture. Can be. The upper limit xenon concentration is reached when the system can no longer compensate for the attenuation due to adduct xenon by increasing the drive voltage to maintain the specified output pulse energy. In order to improve energy stability and overshoot control, it is desirable to include as much xenon in the gas mixture as possible, within the limits of the system components intended to transmit a given output energy.

Extended service life of laser components

The attenuation action of the gas adducts in the gas mixture of the excimer and molecular fluorine lasers is in accordance with the following embodiments of the present invention for increasing the lifetime of laser components, including resonator optics components. Can be used positively. The variation in the quality of various laser components (e.g., optical components in resonators such as prisms, gratings, etalons and windows, as well as laser chambers) is 20-40%. Can lead to a deviation in the output power of the laser system. In addition, the aging of the components with respect to their usage periods causes a reduction in the maximum usable output power over time. This allows to achieve the same output power at higher drive input voltages. The dynamic range of the operating voltage is defined to set an upper limit on the lifetime of the laser components.

The dependence of the output power on the xenon partial pressure will be used positively in accordance with the present invention which extends the service life of these components. The system is initially equipped with excessive laser power when the components are new. That is, the operating range of the voltage is above the value typically required to produce output laser pulses at specified energies (eg between a few mJ and 10 mJ or more). In this case, a predetermined amount of xenon is added to the mixture so that the output power becomes a predetermined value within the operating voltage range.

For example, a 10W ArF laser with an FWHM bandwidth of 0.6pm or less at a 2kHz repetition rate would deliver up to 30 watts of power. The typical dynamic operating range of the drive discharge voltage allows a conventional laser to operate at a minimum of 15W, which is 5W higher than a predetermined 10W power for a laser with new components. According to the present invention, a gas adduct such as xenon is added to the gas mixture in a selected amount to attenuate the laser power and adjust the output power to a predetermined range for the operating range of the driving voltage of the laser system. As the optical and laser tube components age, the xenon partial pressure in the gas mixture is adjusted to different values through each new charge to achieve the same desired output power within the operating voltage range. The xenon concentration is adjusted between new charges through the following gas control method. An exemplary method according to an embodiment of the present invention for increasing the service life of the components is as follows. After a new gas charge of an excimer or molecular fluorine laser (without xenon), the laser is started at a nominal high voltage at the operating point of the laser, and the output power or energy is measured by an energy monitor, and An energy monitor is generally installed internally in the laser system (see the description of FIG. 7). The power for the new charge will be measured higher than a predetermined value, and according to this embodiment, a certain amount of xenon is added to the gas mixture and the power is measured again. The addition of xenon will be repeated and the output power is measured several times until the output power is reduced to within a predetermined value within the operating range of the drive voltage.

In addition, an expert system with a computer database and a processor (see application '034 described above) can store the value of the amount of xenon added after the previous new charge and / or from the previous process of other lasers, The predicted initial amount of xenon added with the current charge can be predicted. And, an initial amount of xenon may be added after the addition of a small amount (for example, 10 ppm) of xenon and after the measurement of the power, and the initial amount may be added to a predetermined amount more practical than the amount described above. close. In this way, the whole process will take less time.

According to this embodiment of the invention, the amount of xenon added to the gas charge will generally decrease as the components age and the maximum output power of the laser system is reduced. As described above, since the service life of the laser components ends when the system cannot achieve the predetermined output power even when operating at the maximum drive voltage, the concentration of the xenon is adjusted to adjust the output power. The advantage of controlling is clearly disclosed in the above process of the invention. This increases the service life of the components (e.g., over 100%).

Gas supply

The concentration of the gas adduct can be adjusted not only with new charges, but also between new charges using the gas supply according to the invention. For this purpose, the source of xenon is preferably integrated with the excimer or molecular fluorine laser system. That is, an internal xenon supply is provided to the laser system. In addition, a predetermined amount of xenon is mixed in a premix with an inert gas of a conventional gas supply of gas supply bottles or vessels external to the laser. After an initially predetermined amount of xenon is first filled with the discharge chamber on a new charge, a gas supply technique is used in accordance with the present invention to maintain and / or control the predetermined amount of optimal xenon in the gas mixture. It is desirable to be. The gist of the preferred technique is disclosed in the '785 and' 034 applications, in particular applied to halogens (or rare gases), but is modified to include concentration control and / or supply of xenon in accordance with the present invention.

Excimer lasers of the general type comprise a gas mixture at a total pressure of 5 bar or less. Typically the majority of the mixture of 90 to 99% consists of the so-called buffer gas. Helium and neon are typical buffer gases. The buffer gas functions to transfer energy. Atoms of the buffer gas are released during the gas discharge and do not become part of the very excited molecules. Rare gases forming very excited excimers, excited complexes or trimers in rare gas-halogen lasers are typically found at lower concentrations in the range of 1 to 9%. Halogen donors are typically 0.1 to 0.2%, in particular dynamic halogen molecules such as F ₂ or HCl or other halogen-containing molecules can be used as the halogen donor. The molecular fluorine laser does not contain an active rare gas in the gas mixture.

The present invention is an excimer or molecular fluorine laser system, in which the laser tube is adapted to receive the injection of a small amount of xenon very precisely as an adduct to the gas mixture. Means are provided to stabilize the optimum xenon partial pressure. Certain techniques, including micro-injections and gas exchange and pressure regulation, are disclosed in the '034 and' 785 applications.

The xenon will be injected in the absence of impurities or as a composition gas in a premix containing a non-inert gas such as Ar, Ne, He, or Kr. In ArF and KrF lasers, a premix of 0.05% Xe at Ar and Kr is preferred, respectively. In another preferred composition, 1.4% Xe in Ne is used as the premix. The present invention is not limited to specific premix concentrations of xenon and buffers and / or other gases. As described below, although the xenon can be supplied from an external gas source, the xenon gas supply is preferably made inside the laser system.

The xenon is scanned at intervals and amounts determined based on the high voltage values and an expert system comprising a processor that receives values such as energy and energy stability and retrieved values of output line parameters. Very small amounts and short intervals are possible, because the gas supply system is so configured (see the '785 application and the' 514 patent).

Parameters consisting of a line profile and other parameters such as temporal and spatial coupling, discharge width, time, shot or pulse count, pulse shape, pulse persistence, pulse stability, bandwidth of the laser line, or a combination of the parameters Will be used. The expert system compares the retrieved values with the stored values to determine what form and to what extent the gas supply processes are performed and which xenon injection or supply is performed depending on the retrieved parameters and to what extent. Using an energy detector, the output energy and energy stability of the laser emission will be measured, and in burst operation the energy overshoot will be measured as the first pulse or the first few pulses of bursts of pulses. If the measured values differ from preset reference values or predetermined values, the amount of xenon in the laser gas mixture is increased by xenon gas injection or by small or partial gas exchange or by gas injections. Will be reduced by the gas emissions associated with it (see '785 application). By searching for and controlling parameters such as laser pulse energy, energy stability and / or burst overshoot after the gas action is performed, it is possible to determine whether an optimal concentration of xenon is in the gas mixture. By searching the parameters and / or other parameters, such as a combination of ASE or temporal pulse shapes (see '052 and' 062 applications), even though the concentrations of xenon and halogen may be reduced to some parameters such as pulse energy, Although affecting, the concentration of the xenon and the concentration of halogen in the gas mixture can be known at any time.

If after the gas operation is performed, it is determined that the optimum concentration of xenon is not in the gas mixture after the laser parameters have been measured, corresponding gas operations are performed and control measurements of the laser parameters have reached the optimum xenon concentration. Is repeated until.

Condensed Matter Xenon Supply

In another embodiment of the present invention, an object of the present invention is when a xenon-containing compressed material is added to the gas discharge chamber of the laser or when it is in physical relationship with the chamber in a manner that enables gas transfer or gas diffusion. Is satisfied. The solids provide the small amount of xenon or xenon-containing combination necessary to achieve the energy-stabilizing effect on the emitted laser radiation pulses which is the object of the present invention.

In this embodiment of the invention, xenon is preferably supplied using solid xenon containing species such as XeF ₂ rather than directly using the gaseous supply of the xenon premix described above. In FIG. 2, xenon gas generator 20 includes a small reservoir 22 filled with xenon containing crystals (such as XeF ₂ ). The storage container 22 may be connected to the laser tube 1 by at least one gas line 23. The valve or valves V1, V2 may be used to separate the reservoir 22 from the laser tube 1. A separate receptacle 26 is used to allow the decomposed xenon and fluorine gases to be mixed prior to injection into the laser tube. A buffer gas is used to allow the xenon fluorine mixture to flow into the laser tube through valve V3. For this purpose, a buffer filling line is connected to the reservoir 26 through the valve V2. The reservoir 26 can be used for precise control of the amount of xenon injected. For this purpose, the respective pressures of the reservoir 26 and the laser tube 10 are monitored prior to injection. The reservoir 26 and its use will be the same or similar to that disclosed for the supply of halogen and active rare gases in the '514 patent and / or' 785 application disclosed above.

The reservoir 22 preferably comprises a heating element 24 and a temperature control device (not shown), such as a conventional temperature controller. The reservoir 22 is preferably heated to a predetermined temperature which causes decomposition of the xenon-containing molecules of the crystal. For example, XeF ₂ is decomposed into xenon gas and F ₂ gas. The generated gas is filled into the laser tube 1 via the reservoir 26 described above or directly. The amount of xenon released depends on the temperature applied to the solid xenon combination. That is, the xenon pressure or partial pressure can be adjusted by controlling the temperature in the reservoir 22. The loss of xenon due to partial gas exchange is automatically compensated for by xenon release from the heated solid combination. The amount of fluorine released is not sufficient for the laser. Thus fluorine and other rare gases are filled into the laser tube in a conventional manner through the above described gas tanks and / or premix bottles.

Exemplary procedures for partial gas exchange according to the invention are described below. First, the valve V1 is closed. Some laser gas is emitted from the laser tube 1 by conventional methods (see US Patent No. 4,977,573, referred to in this application, and pumped to the same assignee). Next, halogen and active rare gases and buffer gases are filled into the laser tube 1 from gas tanks. Then, the valve V1 is opened and the reduced xenon pressure is compensated directly or through the reservoir 26 described above. It is advantageous to connect two gas lines to the gas generator 20 and the laser tube and to circulate a portion of the laser gas through the generator 20. In this way, the stabilization of the xenon pressure is achieved more quickly and is not limited by the rate of diffusion of xenon from the generator 20 into the laser tube 1.

The xenon or xenon-containing material may be injected directly into the gas mixture or added to one of the gas constituents, for example Ne, Kr, Ar, He, or F ₂ , prior to filling. If xenon or xenon-containing material is added to the gas discharge chamber in the form of a solid according to the present embodiment to produce the above-described low xenon concentration in the gas discharge, compressed xenon fluoride (eg XeF ₂ , XeF ₄ , XeF ₆ ) are partially implanted for this purpose and introduced into the laser chamber in advance or during the laser operation. The materials that can be measured (xenon fluorides) are the same during operation (compression) if the laser is operated with fluorine-containing gas combinations (e.g. XeF ^* ) in which xenon or xenon-containing combinations are present. It can accumulate inside the laser chamber. In this case, the compressible xenon fluoride described above is formed during operation of the laser and remains in the laser chamber. Even when the laser is no longer fed with xenon from an external source, the xenon fluoride supplies the gas mixture with the small amount of xenon described above. The remaining portion of the xenon-containing solids in the gas discharge chamber provides the necessary concentration in the ppm range for stabilization of the impulse energy during subsequent laser operation (without additional addition of xenon for several subsequent gas fillings). ).

The invention is operated in such a way that an excimer or molecular fluorine laser is prepared and operated in the presence of xenon with a fluorine containing gas mixture and thus without the addition of additional xenon (within the ppm range), This is achieved when there is a sufficient small amount of xenon in the gas mixture.

Experimental results

3A shows pulse-to-pulse energy stability for numerous bursts including about 240 pulses for a KrF laser system without any xenon adduct in the gas mixture. The KrF was operated at 2 kHz, with the bursts followed by a 0.8 second pause. The pulse energy stability is shown as percent deviation from the steady-state mean. The pulse-to-pulse energy stability of a KrF laser with conventional gas mixing without xenon adducts is shown in FIG. 3A to vary from a minimum value of about 5% to more than 15%. The stability is not particularly good for the first 70 pulses varying between 10% and 15%. After the first 70 pulses, the stability is stable in the range between 7% and 12%.

FIG. 3B shows the energy overshoot of the laser of FIG. 3A as a percentage of the steady state average output energy for the total bursts, each containing about 240 pulses. The overshoot of a KrF laser with a conventional gas mixture without xenon adducts is about 30% for the first pulse or pulses, about 10% after 5-10 pulses, and about 5% after about 25 pulses. It is shown in Figure 3b to decrease. The overshoot is shown to decrease more gently with respect to the remainder of the burst. In the last 50-100 pulses, the effect of the overshoot on the pulse energy is substantially reduced to zero, i.e. the steady-state value is reached.

4A shows the pulse-to-pulse energy stability as in FIG. 3A for a number of bursts each having about 240 pulses for the laser system according to the invention as a percentage of the steady-state average. The laser system of the present invention, in which the output pulse energy is measured and shown in FIG. 4A, is used in the same manner as in FIG. 3A and has a gas mixture comprising about 35 ppm xenon adduct to another type of typical KrF laser gas mixture. The KrF laser was again operated at 2 kHz and the measured bursts followed with a 0.8 second pause. The pulse-to-pulse energy stability in a KrF laser containing 35 ppm xenon adduct in gas mixing varies from below the minimum value of 4% to 12% as shown in FIG. 4A. With the exception of some peaks in the first 60-70 pulses, the stability is shown below 10% for the first pulses where overshoot is typically most prominent. After the first 60-70 pulses, the stability stabilizes in the range between about 3% and 8%.

4b shows the energy overshoot of a burst mode operating KrF laser according to the present invention as a percentage of steady state output energy for the total bursts with about 240 pulses each. As in FIG. 4A, the laser system according to the present invention, in which the output pulse energies are measured and shown in FIG. 4B, had a gas mixture comprising about 35 ppm xenon adduct to another typical krF laser gas mixture. Again, the KrF laser was operated at 2 kHz and the measured burst followed a 0.8 second pause. The overshoot of FIG. 4B shows a sharp decrease to about 9-10% for the first pulse or pulses, to about 3% after 5-10 pulses, and to about 2% after about 20 pulses. The overshoot is shown to be reduced for the remainder of the burst, and the impact of the overshoot on the pulse energies at the last 50-100 pulses is substantially reduced to zero.

At least two major improvements in the output energy stability are the gases used to measure the data of FIGS. 4A-4B for the laser without the xenon adduct used to measure the data of FIGS. 3A-3B. Observed for a laser with the Xe-adduct in the mixture. First, the pulse-to-pulse energy stability shown in FIG. 4A for the laser using the gas mixture with the 35 ppm xenon adduct is less than 12% deviation in all respects, at the start of the burst. Less than 10% deviation for most of the laser pulses, and less than 8% after 100 pulses. The stability demonstrated by the laser in FIG. 4A is markedly improved compared to the laser of FIG. 3A operating without xenon, and the energy stability appears to be 18% higher in some pulses, and at the beginning of the burst. About 15% and remain about 10% after the first 100 pulses. Second, the burst overshoot, defined as the average deviation of the first pulse in the burst from the steady-state energy value, is operated using xenon at 30% of the laser of FIG. 3b operating without xenon. Reduced to less than 10%.

5 shows the dependence of the energy overshoot on the xenon partial pressure in the gas mixture of KrF laser. 5 shows a marked improvement in the overshoot at very low xenon concentrations. That is, the overshoot is reduced from 32% in the absence of the xenon adducts shown in FIG. 3B to 12-13% at about 17 ppm xenon. A reduction to 8% of the overshoot is observed at about 37 ppm xenon, and an additional 2-3% reduction is seen at the xenon concentration of 67 ppm.

When obtaining the experimental results in Table 1, the KrF excimer laser was operated at a repetition rate of 1 kHz. A laser of the Lambda Physik Litho / P type was used. The total gas pressure is 3 bar absolute. Individual components in the gas mixture were present in the following concentrations: 0.1% F ₂ , 1% Kr, 98.9% neon and small amounts of xenon in the range of 10-500 ppm. Pre-ionization was performed using UV sparks, although corona preionization is typically used in KrF as well as ArF and F ₂ laser systems. The application high voltage used during the test was in the order of 15 kV.

The results of the experiment are as follows:

The above experimental results indicate that for the excimer laser used, there is an optimum standard deviation of 0.81 under certain operating conditions (generally, the standard deviation is the square root of the squared deviation of the variables from the mean of the variables). Calculated as). At optimum stability, the pulse energy has been slowly reduced, but in most cases the advantage of stabilization of energy from the emitted laser line impulses is sufficient to overcome the drawback of a slight decrease in output energy, and The slight decrease is compensated by increasing the high voltage in this case.

FIG. 6A is a reciprocal of the percent deviation from the steady state output energy of the laser at xenon concentrations above about 30 ppm, a measurement of the xenon concentration of energy stable sigma of an ArF laser having a bandwidth of 0.6 pm or less and operating in burst mode. Dependencies. 6B shows the measured dependence of the xenon concentration of the energy stability sigma of the ArF laser as a percentage of deviation from steady state output energy at concentrations below 30 ppm. The energy stability in FIG. 6B shows a marked improvement when several ppm of xenon is added to the gas mixture, and in FIG. 6A it is stabilized by increasing the xenon concentration.

6C shows the measured dependence of xenon concentration from 30 to 520 ppm of the output pulse energy of the ArF laser of FIGS. 6A-6B at constant discharge voltage. 6D shows the measured dependence on the xenon concentration from 0 to 30 ppm of the output pulse energy of the ArF laser of FIGS. 6A-6C. The pulse energy is significantly improved when several ppm of xenon is added to the gas mixture in FIG. 6D. The pulse energy shows a substantially linear attenuation from about 5.7 mJ at 30 ppm xenon to about 1 mJ at 500 ppm xenon.

The addition of small amounts of rare gas xenon does not show a negative effect on the quality of the gas discharge. Provided that unstable XeF ^* or stable XeF ₂ , XeF ₄ or XeF ₆ are formed in the gas discharge.

FIG. 6E shows the effect of xenon on the energy stability and output energy of an ArF excimer laser used in 193 nm lithography at a concentration of less than 40 ppm xenon. The dependence of the output energy is shown by showing the high voltage required to maintain an output energy of 5 mJ. The dependence of the output energy on the xenon concentration is qualitatively similar to the results obtained by Wakabayashi et al. FIG. 6E shows that the concentration of xenon that requires the most high voltage to produce maximum output energy or maintain the output energy of 5 mJ is about 10 ppm or less. At 10 ppm, the required high voltage is about 18.9 kV. At xenon concentrations below 10 ppm and above, the high voltage required to maintain the output energy of 5 mJ increases. For example, at 0 ppm and also at about 28 ppm, the required high voltage is about 19.6 kV. At xenon concentrations above 28 ppm, the high voltage continues to increase.

The output energy stability is improved at xenon concentrations of 10 ppm or more, and continues to improve at high xenon concentrations of about 35 ppm. As shown in FIG. 6E, the energy stable sigma is about 3.3% at a xenon concentration of 0 ppm. The energy sigma is improved by about 2.4% between about 17 ppm and 21 ppm. The energy sigma is further improved to 2.1% at about 28 ppm. Based on the data, it is the invention that the optimal xenon concentration is more than producing the least required high voltage to maintain the 5 mJ output energy, but less than producing the required high voltage significantly increased from the minimum value. Is recognized. The optimal xenon concentration, in the embodiment of the present invention to improve the combination of the energy stability sigma and the output pulse energy, the two line segments shown in Figure 6e, that is, high voltage and energy for the xenon concentration graph Based on sigma. The optimal xenon concentration for the laser system in the preferred embodiment is between about 10 ppm and 30 ppm in the ArF laser.

As shown in FIG. 6E, the energy stability is markedly improved to 2.8% or less and 2.7% or less at 12 ppm xenon concentration. The energy stability is improved at higher xenon concentrations. Thus, according to the invention, an ArF laser is provided having a xenon concentration of 12 ppm or more. This improved energy stability is a particular advantage of excimer lasers for use in connection with imaging systems in the photolithography field. A similar improvement in the energy stability is expected in 157 nm molecular fluorine (F ₂ ) lasers when a small amount of gas adduct such as xenon is added to the gas mixture. Specific optimal concentrations of xenon are based on similar studies of sigma and high voltage on xenon concentration graphs measured using molecular fluorine lasers.

Desirable Laser System

7 shows a preferred embodiment of a KrF, ArF, ArF ₂ or F ₂ laser system according to the present invention. FIG. 7 shows various modules of an excimer or molecular fluorine laser for deep ultraviolet (DUV) or vacuum ultraviolet (VUV) lithography using radiation of about 248 nm, 193 nm or 157 nm, respectively. The discharge chamber 1 comprises a laser gas mixture and has a pair of main discharge electrodes 1a, 1b and one or more pre-ionization electrodes (not shown). Exemplary electrode configurations are equally assigned to the assignee of the present application and are disclosed in US Provisional Patent Application No. 60 / 128,227, which is incorporated herein by reference. Exemplary preionization combinations are equally assigned to the assignee of the present application, and are disclosed in US Patent Application Nos. 09 / 247,887, 60 / 160,182, and 60 / 162,645, which are incorporated herein by reference.

The laser resonator surrounding the discharge chamber 1 comprising the laser gas mixture comprises a line narrowing module 2 and an outcouple for a line narrowed excimer or molecular fluorine laser. With an outcoupling module 3, the line narrowing module 2 can be replaced with a high reflecting mirror or the like if line-narrowing is not desired. There are many alternative line-narrow configurations that can be used, depending on the type and range and / or selection and desired tuning of the line-narrow, and the particular laser on which the line-narrow module is installed. For this purpose, U.S. Pat. Patent applications 09 / 317,695, 09 / 130,277, 09 / 244,554, 09 / 317,527, 09 / 073,070, 60 / 124,241, 60 / 140,532 and 60 / 140,531 and present Nos. 5,095,492, 5,684,822, 5,835,520, 5,852,627, 5,856,991, 5,898,725, 5,901,163, 5,917,849, 5,970,082, 5,404,366, 4,975,919 5,142,543, 5,596,596, 5,802,094, 4,856,018, and 4,829,536.

The discharge chamber is sealed by a window 8 transparent to the emitted laser radiation 14 of the wavelength length. After a portion of the output line passes through the outcoupler 3, the output portion collides with the line splitter 6 reflecting the portion of the line to a second line splitter 7. Some of the lines impinging on the second line splitter are reflected by the high speed energy detector 5, and the remaining lines are received by the band-width and wavelength length meter 4 across the line splitter. Some outcoupled lines across the line splitter 6 are the output emissions of the laser, which are disseminated to industrial or experimental applications such as light sources for photolithography applications.

The pulsed power module 9 and the high voltage power supply 10 supply electrical energy to the main electrodes 1a and 1b to energize the gas mixture. Preferred pulse power modules and high voltage power sources are disclosed in U.S. Patent Applications 08 / 842,578, 08 / 822,451, and 09 / 390,146, which are equally assigned to the assignee of the present application and referenced herein.

A processor or control computer 11 receives and / or processes values of energy, energy stability, wavelength length, and bandwidth of the output line, controls the line narrowing module to adjust the wavelength length, and configures the power supply source. The energy is controlled by adjusting elements 9 and 10. In addition, the processor 1 controls a gas supply unit having a gas supply valve 12 and a gas adjunct source 13, which may be inside or outside the laser system. In the KrF laser, a preferred gas adduct supply of xenon is inside the laser system. In the ArF laser, a preferred gas adduct supply, along with an external gas supply (not shown) of other gases of the system, such as halogen containing gas, active rare gas and buffer gas through gas tube 17, is provided. Managed outside of The ArF laser also has an internal supply of xenon or other gas adducts or an external supply of other gas adducts other than xenon. The KrF laser has an external supply of xenon or other gas adducts or an internal supply of xenon. . The xenon and / or other gas adducts are connected to the gas source through a suitable gas tube 15. The gas supply valves are connected to the laser tube via another gas tube 16, which is preferably connected to a vacuum pump 18 or other low pressure source.

As indicated by the '875 application for halogen-containing and other gases in the system, when the processor determines that xenon injection has been performed, a compartment is first filled with the xenon at the indicated pressure (the For purposes, see US Pat. No. 5,396,514, which is equally assigned to the assignee of the present application and referenced in this application, see the '785 application referred to above). Then, the xenon is injected into the tube (1). In this way, it is possible to more accurately determine the amount of xenon injected into the tube, taking into account the volume of the compartment, as well as the pressure filled with xenon and the pressure of the tube. The system preferably reduces the pressure in the tube 1, or if the partial pressure of one of the gases, such as xenon, is determined to be too high, or if the gas supply operation, such as partial gas supply, If a small gas exchange as is carried out or if a new filling is carried out, the system is provided with means for releasing the gas comprising xenon from the tube 1.

As described above, the gas compartment of the laser has a source or source 13 of xenon. The xenon resource 13 is connected to the gas tube 15 if additional valves to the gas supply valve 12 are required. A standard gas mixture is supplied to the laser by an external gas supply via the gas supply tube 17.

The new charge of the laser is automatically controlled by the control computer 11. In the present invention, xenon gas from the xenon resource 13 is injected into the discharge chamber 1 with high accuracy during a new charge. The injection may be carried out in a preferred form of the invention after the pressure in the discharge chamber 1 is reduced to a predetermined low pressure value, for example about 20-30 m, before the new gas filling is initiated. will be. In another preferred embodiment of the invention, the xenon injection is performed at the end of the new charge when the standard gas mixture is already filled.

The present invention comprising adding xenon to the gas mixture at a predetermined concentration is particularly advantageous at high repetition rates. That is, the performance of the laser at moderate repetition rates (eg 1 kHz or below, such as from 1 to 300 or 500 Hz) depends on the addition of Xe to the mixture when operating at high repetition rates of 1 kHz or higher. No favorable change is observed. The operation of the laser at high repetition rates (approximately 1 kHz and above) due to the addition of xenon is significantly improved and the power of the laser at higher repetition rates is nearly linear and pulse-to-pulse energy stability (standard deviation) is better lost.

The proper operation of the laser at high repetition rates depends on various factors. Repetitive and very strong periodic gas discharges in the discharge chamber 1 are improved by continuously refreshing the gas in the region between the electrodes. Although strong gas flow between the electrodes 1a, 1b is not an important condition, the present invention demonstrates the importance of the gas mixture composition, which includes maintaining a gas concentration of the correct composition.

The pulse-to-pulse energy stability of laser output radiation depends not only on the general stability of the electric pulse generator used for pumping of the electrical discharge, but also on the power of the laser excitation of the gas discharge process ( kinetics and the specific characteristics of the building-up process of the laser pulse. An increase in the intensity of the pre-ionization of the gas is achieved in the present invention by the addition of a small amount of xenon to the gas mixture according to the desired concentration, providing a significant improvement in pulse-to-pulse stability.

It is shown that the objects of the present invention have been met in the present embodiments. The addition of small amounts of xenon is managed at the correct concentration and improves the laser operation, especially at high repetition rates. That is, the improvement in laser performance at high repetition rates is advantageously achieved with reference to pulse-to-pulse energy stability (standard deviation).

The object of the invention met

The various embodiments of the present invention described above address the object of the present invention by adjusting the concentration of xenon added to the gas mixture of an excimer or molecular fluorine laser to adjust the pulse energy, energy stability and overshoot control of the laser. Meets. The laser includes a device for supplying xenon to the laser gas mixture and a method of injecting and controlling an appropriate amount of xenon into the gas mixture of the gas discharge tube of the laser. The present invention provides an optimal balance between the highest energy stability and overshoot control and the energy output of the laser depending on the constraints imposed by the laser system and other components of certain line parameter specifications. To achieve. The present invention extends the service life of the components, as described above.

The above features of the present invention are achieved in the present invention based on the investigation of energy stability, overshoot control and output power dependencies on the concentration of xenon in the laser chamber. Experimental data is detailed to illustrate the advantages described above with respect to specific embodiments of the present invention.

The xenon-containing combinations or small amounts of xenon in the gas mixture of the excimer laser in the present invention are more likely for other reasons, for example because the exciteted complex contains xenon (eg XeF, or XeCl). A fluorine-containing excimer laser gas mixture containing no positive xenon is shown. The concentration of xenon added to the gas mixture according to the invention (up to 2000 ppm in KrF, in particular ArF laser) does not make xenon-containing gas mixtures in excimer lasers the subject of the invention.

The optimum concentration of the small amount of xenon in the gas mixture mentioned in the present invention depends on the characteristics and conditions of the excimer laser in the individual case and cannot be set for all types of excimer lasers to an optimum value. . Optimal xenon concentrations for each type of laser must be determined experimentally. For example, the present invention produces particularly good results when the excimer laser is operated at relatively high repetition rates, in particular at repetition rates higher than 100 Hz, and especially at repetition rates higher than 500 Hz.

As described above, the concentration of xenon or the substance supplying xenon does not increase indefinitely to the gas mixture, but reaches an optimum value depending on various laser parameters, such that the gas mixture used, the form of preionization, The configuration of the electric gas discharge (particularly, the shape of the electrode and the conditions of the electrode) and the external electric circuit are varied for each type of laser. The concentration will be optimized empirically for each laser type.

Those skilled in the art will recognize that only the preferred embodiments disclosed are susceptible to numerous changes and modifications without departing from the scope and spirit of the invention. Thus, within the scope and spirit of the invention, the invention may be practiced otherwise than as specifically described. The scope of the invention is not limited to the specific embodiments described above. Instead, it is understood that the scope of the present invention is defined by the language, structure and functional equivalents of the following claims.

Claims (107)

A discharge chamber initially filled with a gas mixture comprising argon, fluorine, a buffer gas and at least 100 ppm of xenon; A plurality of electrodes in said discharge chamber connected to a discharge circuit for energizing said gas mixture; And a resonator device surrounding said discharge chamber to produce an output laser line. 2. The ArF laser according to claim 1, wherein the gas mixture contains 2000 ppm or less of xenon. A discharge chamber initially filled with a gas mixture comprising argon, fluorine, a buffer gas and an energy attenuating gas adduct; A plurality of electrodes in the discharge chamber connected to a discharge circuit for applying energy to the gas mixture; And a resonator surrounding said discharge chamber to produce an output laser line, wherein the concentration of said gas adduct in said gas mixture is adjusted to control the energy stability of said laser line. 4. The ArF laser according to claim 3, wherein the concentration of the gas adduct in the gas mixture is adapted to control the energy overshoot of the laser line when the laser operates in burst mode. A discharge chamber initially filled with a gas mixture comprising argon, fluorine, a buffer gas and an energy attenuating gas adduct; A plurality of electrodes in the discharge chamber connected to a discharge circuit for applying energy to the gas mixture; A resonator surrounding the discharge chamber to produce an output laser line, wherein the concentration of xenon in the gas mixture is adapted to control the energy overshoot of the laser line when the laser operates in burst mode ArF laser. 6. The ArF laser according to claim 4 or 5, wherein the energy overshoot is adjusted to 20% or less by adjusting the concentration of the gas adduct. 6. The ArF laser according to claim 4 or 5, wherein the energy overshoot is adjusted to 10% or less by adjusting the concentration of the gas adduct. 6. The ArF laser according to claim 4 or 5, wherein the energy overshoot is adjusted to 5% or less by adjusting the concentration of the gas adduct. 6. The ArF laser according to any one of claims 3 to 5, wherein the concentration of gas adducts in the gas mixture is adapted to control one of the pulse energy and the energy dose of the laser line. A discharge chamber initially filled with a gas mixture comprising argon, fluorine, a buffer gas and a gas adduct; A plurality of electrodes in the discharge chamber connected to a discharge circuit for energizing the gas mixture; And a resonator surrounding the discharge chamber to produce an output laser line, wherein the concentration of gas adducts in the gas mixture is actively controlled during laser operation to control the pulse energy. 11. The ArF laser according to claim 10, wherein the concentration of the gas adduct in the gas mixture is adapted to adjust the pulse energy in a range substantially between 3.5 mJ and 15 mJ. 11. The ArF laser of claim 10 wherein the concentration of gas adduct in the gas mixture is adapted to adjust the pulse energy in a range substantially between 4.0 mJ and 5.5 mJ. 13. The ArF laser according to claim 12, wherein the energy overshoot is adjusted to 20% or less by adjusting the concentration of the gas adduct. 13. The ArF laser according to claim 12, wherein the energy overshoot is controlled to 10% or less by adjusting the concentration of the gas adduct. 13. The ArF laser according to claim 12, wherein the energy overshoot is adjusted to 5% or less by adjusting the concentration of the gas adduct. A system for photolithographically forming a structure on a silicon wafer, the system comprising: An ArF laser system; An imaging system with optics for illuminating a laser line onto a silicon wafer, the ArF laser system comprising: A discharge chamber initially filled with a gas mixture comprising argon, fluorine, a buffer gas and 12 ppm or more of xenon; A plurality of electrodes in the discharge chamber connected to a discharge circuit for energizing the gas mixture; And a resonator device surrounding the discharge chamber to produce an output laser line. 17. The photolithography etching system of claim 16, wherein the ArF laser further includes a gas processing unit that supplies the gas mixture periodically during operation of the laser. 18. The photolithography etch system of claim 17, wherein the ArF laser further comprises a processor for monitoring one or more parameters of the laser line and supplying the gas mixture depending on the values of the retrieved one or more parameters. 17. The photolithography etch system of claim 16, wherein the imaging system includes total reflection optics and the ArF laser further includes a line-narrow unit to reduce the bandwidth of the ArF laser to less than 100 pm. . 17. The photolithography etch system of claim 16, wherein the imaging system includes refractive optics and the ArF laser further includes a line-narrow unit to reduce the bandwidth of the ArF laser to 0.8 pm or less. . 17. The photolithography etch system of claim 16, wherein the system further comprises one of a mask and a reticle to form the structure on the wafer. 17. The photolithography etch system of claim 16, wherein the system further comprises a monitor etalon for wavelength length measurements. A discharge chamber initially filled with a gas mixture comprising argon, fluorine, and a buffer gas and attenuating gas adduct; A plurality of electrodes in the discharge chamber connected to a discharge circuit for energizing the gas mixture; A resonator surrounding the discharge chamber to produce an output laser line, the output laser line having a specified energy, and wherein the discharge circuit applies an operating drive voltage to the electrodes in the gas mixture. ArF laser characterized in that it is applied to the electrodes in a range of a minimum driving voltage or higher to generate a laser line above the specified energy without the attenuation gas of. A discharge chamber initially filled with a gas mixture having argon, fluorine, a buffer gas and 17 ppm or more of xenon attenuators; A plurality of electrodes in said discharge chamber connected to a discharge circuit for energizing said gas mixture; And a resonator surrounding the discharge chamber to produce an output laser line, wherein the energy of the output pulses of the laser is lower than the energy when xenon is not included in the gas mixture. The ArF laser of claim 24, wherein the xenon concentration is 30 ppm or more. A discharge chamber initially filled with a gas mixture comprising argon, fluorine, a buffer gas and xenon; A plurality of electrodes in a discharge chamber connected to a discharge circuit for applying energy to the gas mixture; A resonator surrounding the discharge chamber to produce an output laser line; And a gas control unit comprising a supply of xenon into the laser housing. 27. The ArF laser of claim 26, wherein the gas control unit comprises a xenon generator comprising a supply of compressed material xenon in a controlled environment to supply the xenon gas. A discharge chamber initially filled with a gas mixture containing krypton, fluorine, a buffer gas and at least 100 ppm of xenon; A plurality of electrodes in said discharge chamber connected to a discharge circuit for energizing said gas mixture; And a resonator device surrounding said discharge chamber to produce an output laser line. 29. The KrF laser according to claim 28, wherein the gas mixture comprises 2000 ppm or less of xenon. A discharge chamber initially filled with a gas mixture comprising krypton, fluorine, and a buffer gas and attenuating gas adduct; A plurality of electrodes in the discharge chamber connected to a discharge circuit for applying energy to the gas mixture; And a resonator surrounding said discharge chamber to produce an output laser line, wherein the concentration of said dampening gas adduct in said gas mixture is adjusted to control energy stability of said laser line. 31. The KrF laser of claim 30, wherein the concentration of gas adduct in the gas mixture is adapted to control the energy overshoot of the laser line when the laser operates in burst mode. A discharge chamber initially filled with a gas mixture comprising krypton, fluorine, and a buffer gas and attenuating gas adduct; A plurality of electrodes in the discharge chamber connected to a discharge circuit for applying energy to the gas mixture; A resonator surrounding the discharge chamber to produce an output laser line, wherein the concentration of attenuated gas adduct in the gas mixture is adapted to control the energy overshoot of the laser line when the laser operates in burst mode. KrF laser, characterized in that. 33. The KrF laser according to claim 31 or 32, wherein the energy overshoot is adjusted to 20% or less by adjusting the concentration of the gas adduct. 33. The KrF laser according to claim 31 or 32, wherein the energy overshoot is adjusted to 10% or less by adjusting the concentration of the gas adduct. 33. The KrF laser according to claim 31 or 32, wherein the energy overshoot is adjusted to 5% or less by adjusting the concentration of the gas adduct. 33. The KrF laser according to any one of claims 30 to 32, wherein the concentration of gas adducts in the gas mixture is adapted to control one of the pulse energy and the energy dose of the laser line. A discharge chamber initially filled with a gas mixture comprising argon, fluorine, a buffer gas and a gas adduct; A plurality of electrodes in the discharge chamber connected to a discharge circuit for energizing the gas mixture; And a resonator surrounding the discharge chamber to produce an output laser line, wherein the concentration of gas adducts in the gas mixture is actively controlled during laser operation to control the pulse energy. 38. The KrF laser of claim 37, wherein the concentration of gas adduct in the gas mixture is adapted to adjust the pulse energy in a range substantially between 3.5 mJ and 15 mJ. 38. The KrF laser according to claim 37, wherein the concentration of gas adducts in the gas mixture is adapted to adjust the pulse energy in a range substantially between 4.0 mJ and 5.5 mJ. 40. The KrF laser of claim 39, wherein the energy overshoot is controlled to 20% or less by adjusting the concentration of the gas adduct. 40. The KrF laser of claim 39, wherein the energy overshoot is controlled to 10% or less by adjusting the concentration of the gas adduct. 40. The KrF laser of claim 39, wherein the energy overshoot is controlled to 5% or less by adjusting the concentration of the gas adduct. A system for photolithographically forming a structure on a silicon wafer, the system comprising: KrF laser system; An imaging system with optics for illuminating a laser line onto a silicon wafer, the KrF laser system comprising: A discharge chamber initially filled with a gas mixture comprising argon, fluorine, a buffer gas and 12 ppm or more of xenon; A plurality of electrodes in the discharge chamber connected to a discharge circuit for energizing the gas mixture; And a resonator device surrounding said discharge chamber to produce an output laser line. 44. The photolithography system of claim 43, wherein the KrF laser further includes a gas processing unit that supplies the gas mixture periodically during operation of the laser. 45. The photolithography system of claim 44, wherein the KrF laser further comprises a processor for monitoring one or more parameters of the laser line and supplying the gas mixture depending on the values of the retrieved one or more parameters. 20. The photolithography system of claim 19, wherein the imaging system comprises total reflection optics and the KrF laser further includes a line-narrow unit to reduce the bandwidth of the KrF laser to less than 100 pm. . 44. The photolithography system of claim 43, wherein the imaging system comprises refractive optics and the KrF laser further includes a line-narrow unit to reduce the bandwidth of the KrF laser to less than 0.8 pm. . 44. The photolithography system of claim 43, wherein the system further comprises one of a mask and a reticle to form the structure on the wafer. 44. The photolithography system of claim 43, wherein the system further comprises a monitor etalon for wavelength length measurements. A discharge chamber initially filled with a gas mixture comprising argon, fluorine, and a buffer gas and attenuating gas adduct; A plurality of electrodes in the discharge chamber connected to a discharge circuit for energizing the gas mixture; A resonator surrounding the discharge chamber to produce an output laser line, the output laser line having a specified energy, and wherein the discharge circuit applies an operating drive voltage to the electrodes in the gas mixture. A KrF laser, characterized in that it is applied to the electrodes in a range of at least a minimum driving voltage or higher that produces a laser line above the specified energy without the attenuation gas of. In the KrF laser, the laser is: A discharge chamber initially filled with a gas mixture having argon, fluorine, a buffer gas and 17 ppm or more of xenon attenuators to attenuate the pulse energy of said laser; A plurality of electrodes in said discharge chamber connected to a discharge circuit for energizing said gas mixture; And a resonator device surrounding the discharge chamber to produce an output laser line. 52. The KrF laser according to claim 51, wherein the xenon concentration is 30 ppm or more. A discharge chamber initially filled with a gas mixture comprising argon, fluorine, a buffer gas and xenon; A plurality of electrodes in a discharge chamber connected to a discharge circuit for applying energy to the gas mixture; A resonator surrounding the discharge chamber to produce an output laser line; And a gas control unit comprising a supply of xenon into the laser housing. 54. The KrF laser of claim 53 wherein the gas control unit comprises a xenon generator comprising a supply of compressed material xenon in a controlled environment to supply the xenon gas. In an excimer or molecular fluorine laser that produces an output line at a particular energy, the laser is: A discharge chamber initially filled with a gas mixture comprising an active rare gas, a halogen containing gas, a buffer gas and a noble gas adduct, and the attenuation noble gas is any other than the active rare gas and the buffer gas. Selected from the group comprising noble gases; A plurality of electrodes in the discharge chamber connected to a discharge circuit for energizing the gas mixture; And a resonator that surrounds the discharge chamber to produce the output line at the specific energy, wherein the specific energy is less than the laser outputs without attenuating noble gas adducts in the gas mixture. Excimer or molecular fluorine laser. 56. The apparatus of claim 55, wherein the discharge circuit applies an operational drive voltage to the electrodes at or above a minimum drive voltage that, when applied to the electrode, produces a laser line that is above the specific energy without xenon in the gas mixture. Or an excimer or molecular fluorine laser. In an excimer or molecular fluorine laser system for producing an output line at a particular energy, the system is: A discharge chamber initially filled with a gas mixture comprising an active rare gas, a halogen-containing gas and a buffer gas and a small amount of attenuating gas adduct that attenuates the output line to the specific energy; A plurality of electrodes in the discharge chamber connected to a discharge circuit for energizing the gas mixture; An excimer or molecular fluorine laser system comprising a resonator surrounding said discharge chamber to produce said output line at said particular energy. 58. The drive circuit of claim 57, wherein the discharge circuit applies an operating drive voltage to the electrodes in the range of or above a minimum drive voltage that, when applied to the electrode, produces a laser line that is above the specific energy without xenon in the gas mixture. Or an excimer or molecular fluorine laser system. A discharge chamber initially filled with a gas mixture comprising fluorine, a buffer gas and a small amount of noble gas adduct, and the noble gas adduct is selected from the group consisting of argon, xenon and krypton; A plurality of electrodes in a discharge chamber connected to a discharge circuit for energizing the gas mixture; And a resonator device surrounding said discharge chamber to produce an output laser line of about 157 nm. 60. The molecular fluorine laser of claim 59, wherein the gas adduct attenuates energy of the laser line. 60. The minimum drive voltage of claim 59 wherein the output laser line has a specific energy and the discharge circuit generates a laser line above the specified energy without a small amount of gas adduct in the gas mixture when applied to the electrode. A molecular fluorine laser, characterized in that to apply a driving voltage to the electrodes in the range or more than. 60. The laser of claim 59, wherein the laser is: A detector for monitoring a parameter indicative of the concentration of gas adduct in the gas mixture; And a gas control unit for supplying gas adducts depending on the values of the monitored parameters. 63. The molecular fluorine laser of claim 62, wherein said gas control unit comprises an internal source of said gas adduct. 63. The molecular fluorine of claim 62 wherein said gas adduct is xenon and said gas control unit comprises a xenon generator comprising a source of compressed material xenon in a controlled environment for supplying said xenon gas. laser. A method of operating an excimer or molecular fluorine laser to increase the lifetimes of laser components, the method comprising: Filling the laser with a gas mixture comprising a small amount of attenuated gas; Measuring the output energy of the laser system at a predetermined discharge voltage; And additionally adding the gas type to the gas mixture to reduce the output energy of the laser system at the predetermined discharge voltage. 66. The method of claim 65, wherein the predetermined discharge voltage is the minimum voltage available at the laser. 66. The method of claim 65, wherein said adding step reduces said output energy to a selected energy that is not usable without performing said adding step. 67. An excimer or molecular fluorine according to claim 65 or 67, wherein the steps are repeated again later and less attenuating gas species is added to reduce the output energy to the same energy as after the original steps. How to drive a laser. 69. The excimer or molecular fluorine laser of claim 68, wherein the filling and measuring steps are repeated later and no gas adduct is added because the output energy is the same energy as the original steps. How to drive. 69. The method of claim 68, wherein the type of attenuation is xenon. 68. A method according to any one of claims 65 to 67 wherein the attenuation type is xenon. A method of initiating an excimer or molecular fluorine laser having a gas mixture comprising a small amount of energy dampening gas and emitting an output laser line, the method comprising: Selecting a value of energy stability; Injecting into said laser a gas mixture comprising a selected amount of attenuating gas to control said energy stability to said selected value. 73. The method of claim 72, wherein the method is: Measuring the energy stability of the laser line; And adjusting the concentration of said dampening gas to control the value of said energy stability. A method of initiating an excimer or molecular fluorine laser having a gas mixture comprising a small amount of energy decay gas and emitting an output laser line in burst mode, the method comprising: Selecting a value of the energy overshoot; Injecting a gas mixture comprising a selected amount of energy attenuating gas into the laser to control the energy overshoot to the selected value. 75. The method of claim 74, wherein the method is: Measuring an energy overshoot of the laser line; And adjusting the concentration of the energy attenuating gas to control the value of the energy overshoot. A method of initiating an excimer or molecular fluorine laser having a gas mixture comprising a small amount of attenuated gas adduct and emitting an output laser line in burst mode, the method comprising: Selecting a value of pulse energy at a predetermined discharge voltage; Injecting a gas mixture comprising the selected amount of gas adduct into the laser to attenuate the pulse energy to the selected value. The method of claim 76, wherein the method is: Measuring pulse energy of the laser line; And adjusting the concentration of said gas adduct to control the value of said pulse energy. In a method of operating an excimer or molecular fluorine laser, the laser has a discharge chamber for holding a laser gas mixture, the laser having a range between a minimum voltage and a maximum voltage to generate output laser pulses. An electrical discharge circuit for generating an excitation voltage, wherein the energy of each output pulse is within a predetermined range defined by a minimum level and a maximum level, the method comprising: Filling the discharge chamber with a gas mixture comprising a small amount of attenuating gas, wherein the proportion of gases in the mixture is equal to the pulse even if the laser is excited to the minimum voltage, if no attenuating gas is present in the mixture. Sugar energy is selected to exceed the maximum level, and the damping gas causes the laser to generate pulses having energy within the predetermined range; Adjusting the compositions of the gas mixture over time as the laser gas mixture ages, wherein adjusting includes maintaining the energy per pulse within the predetermined range as the gas mixture ages. Lowering the concentration of the dampening gas in the gas mixture to drive an excimer or molecular fluorine laser. 80. The method of claim 78, wherein said dampening gas is xenon. 79. The method of claim 78, wherein the method is: Monitoring the energy of the laser pulses; Adjusting said voltage to maintain said energy per pulse within said predetermined range. 81. The excimer of any one of claims 78 to 80, wherein the method further comprises adjusting the proportion of the dampening gas to maintain the energy per pulse in the predetermined range. Or how to drive a molecular fluorine laser. A method of operating an excimer or molecular fluorine laser, the laser having a discharge chamber for holding a laser gas mixture, the laser having a range between a minimum voltage and a maximum voltage to produce output laser pulses. An electrical discharge circuit for generating an excitation voltage, wherein the energy of each output pulse is within a predetermined range defined by a minimum level and a maximum level, the method comprising: Monitoring the energy of the laser output pulses; Adjusting the voltage to maintain the energy per pulse in the predetermined range; Adjusting the proportion of the damping gas during laser operation to maintain the energy per pulse in the predetermined range. A method of operating an excimer or molecular fluorine laser, the laser having a discharge chamber for holding a laser gas mixture, the laser having a range between a minimum voltage and a maximum voltage to produce output laser pulses. And an electrical discharge circuit for generating an excitation voltage, said energy dose being in a predetermined range defined by minimum and maximum levels, said method comprising: Filling the discharge chamber with a gas mixture comprising a small amount of attenuating gas, wherein the proportion of gases in the mixture is determined if the laser is excited to the minimum voltage, if no attenuating gas is present in the mixture. The dose is selected to exceed the maximum level and the damping gas causes the laser to generate pulses such that the energy dose is kept within the predetermined range; Adjusting the compositions of the gas mixture over time as the laser gas mixture ages, wherein adjusting includes maintaining the energy per pulse within the predetermined range as the gas mixture ages. Lowering the concentration of said dampening gas in said gas mixture, wherein said energy dose can be maintained within said predetermined range. 84. The method of claim 83, wherein said dampening gas is xenon. 84. The method of claim 83, wherein the method is: Monitoring the energy dose; And adjusting said voltage to maintain said energy dose within said predetermined range. 86. An excimer or molecular fluorine laser according to any of claims 83 to 85, wherein said method adjusts the proportion of said damping gas to maintain said energy dose within said predetermined range. How to. A method of operating an excimer or molecular fluorine laser, the laser having a discharge chamber for holding a laser gas mixture, the laser having a range between a minimum voltage and a maximum voltage to produce output laser pulses. And an electrical discharge circuit for generating an excitation voltage, said energy dose being in a predetermined range defined by minimum and maximum levels, said method comprising: Monitoring the energy dose; Adjusting the voltage to maintain the energy dose within the predetermined range; Adjusting the proportion of the damping gas during laser operation such that the energy dose is maintained within the predetermined range. A method of operating an excimer or molecular fluorine laser, the laser having a discharge chamber for holding a laser gas mixture, the laser having a range between a minimum voltage and a maximum voltage to produce output laser pulses. And an electrical discharge circuit for generating an excitation voltage, wherein said energy stability is within a predetermined range defined by minimum and maximum levels, said method comprising: Filling the discharge chamber with a gas mixture comprising a small amount of attenuating gas, wherein the proportion of gases in the mixture is determined if the laser is excited to the minimum voltage, if no attenuating gas is present in the mixture. Wherein said energy stability is selected to exceed said maximum level and said dampening gas is wherein said laser generates pulses such that said energy stability is maintained within said predetermined range. . A method of operating an excimer or molecular fluorine laser, the laser having a discharge chamber for holding a laser gas mixture, the laser having a range between a minimum voltage and a maximum voltage to produce output laser pulses. And an electrical discharge circuit for generating an excitation voltage, wherein said energy overshoot is within a predetermined range defined by a minimum level and a maximum level. Filling the discharge chamber with a gas mixture comprising a small amount of attenuating gas, wherein the proportion of gases in the mixture is determined if the laser is excited to the minimum voltage, if no attenuating gas is present in the mixture. The energy overshoot is selected to exceed the maximum level and the damping gas drives the excimer or molecular fluorine laser, wherein the laser generates pulses such that the energy overshoot is maintained within the predetermined range. How to. 24. The method of claim 3, 5 or 23, wherein the damping gas is xenon, krypton, WF _X , PtF _X , chromium-containing species, aluminum-containing species, silicon-containing species, HF, HF ₂ , ozone, mercury, hafnium, CRO _X , FO _X , AlO _X , HF _X , CF _X , CF ₄ , CF ₆ , CF ₈ , CF ₃ , CrOF, CrO ₂ F, CrO ₂ F ₂ , CrO ₂ , CrO , Cr, CrF ₂ , CrF, SiF ₄ , SiF, OF, O ₂ F, OF ₂ , Al, AlO, Al ₂ O, Al ₂ O ₂ , AlF, AlF ₂ , N, N ₂ , N _X , C, An ArF laser selected from the group consisting of C ₂ , C _X , H, H ₂ , H _X , O and O _X , wherein X is an integer from 3 to 16. The gas adduct according to claim 10, wherein the gas adduct is xenon, krypton, WF _X , PtF _X , chromium-containing species, aluminum-containing species, silicon-containing species, HF, HF ₂ , ozone, mercury, hafnium, CRO _X , FO _X , AlO _X , HF _X , CF _X , CF ₄ , CF ₆ , CF ₈ , CF ₃ , CrOF, CrO ₂ F, CrO ₂ F ₂ , CrO ₂ , CrO, Cr, CrF ₂ , CrF, SiF ₄ , SiF, OF, O ₂ F, OF ₂ , Al, AlO, Al ₂ O, Al ₂ O ₂ , AlF, AlF ₂ , N, N ₂ , N _X , C, C ₂ , C _X , H, H ₂ , An ArF laser selected from the group consisting of H _X , O and O _X , wherein X is an integer from 3 to 16. 51. The damping gas of claim 30, 32, or 50, wherein the damping gas is xenon, argon, WF _X , PtF _X , chromium-containing species, aluminum-containing species, silicon-containing species. , HF, HF ₂ , Ozone, Mercury, Hafnium, CRO _X , FO _X , AlO _X , HF _X , CF _X , CF ₄ , CF ₆ , CF ₈ , CF ₃ , CrOF, CrO ₂ F, CrO ₂ F ₂ , CrO ₂ , CrO, Cr, CrF ₂ , CrF, SiF ₄ , SiF, OF, O ₂ F, OF ₂ , Al, AlO, Al ₂ O, Al ₂ O ₂ , AlF, AlF ₂ , N, N ₂ , N KrF laser selected from the group consisting of _X , C, C ₂ , C _X , H, H ₂ , H _X , O and O _X , X is an integer from 3 to 16. 38. The method of claim 37, wherein the gas adduct is xenon, argon, WF _X , PtF _X , chromium-containing species, aluminum-containing species, silicon-containing species, HF, HF ₂ , ozone, mercury, hafnium, CRO _X , FO _X , AlO _X , HF _X , CF _X , CF ₄ , CF ₆ , CF ₈ , CF ₃ , CrOF, CrO ₂ F, CrO ₂ F ₂ , CrO ₂ , CrO, Cr, CrF ₂ , CrF, SiF ₄ , SiF, OF, O ₂ F, OF ₂ , Al, AlO, Al ₂ O, Al ₂ O ₂ , AlF, AlF ₂ , N, N ₂ , N _X , C, C ₂ , C _X , H, H ₂ , KrF laser selected from the group consisting of H _X , O and O _X , wherein X is an integer from 3 to 16. 57. The method of claim 56, wherein the attenuation gas is xenon, argon, krypton, WF _X , PtF _X , chromium-containing species, aluminum-containing species, silicon-containing species, HF, HF ₂ , ozone, mercury, hafnium, CRO _X , FO _X , AlO _X , HF _X , CF _X , CF ₄ , CF ₆ , CF ₈ , CF ₃ , CrOF, CrO ₂ F, CrO ₂ F ₂ , CrO ₂ , CrO, Cr, CrF ₂ , CrF, SiF ₄ , SiF, OF, O ₂ F, OF ₂ , Al, AlO, Al ₂ O, Al ₂ O ₂ , AlF, AlF ₂ , N, N ₂ , N _X , C, C ₂ , C _X , H, H ₂ , H _X , O and O _X , wherein X is an integer from 3 to 16. 89. The method of any of claims 60 or 71 or 73 or 75 or 77 or 77 or 81 or 82 or 86 or 87 or 88, wherein the damping gas is Xenon, argon, krypton, WF _X , PtF _X , chromium-containing, aluminum-containing, silicon-containing, HF, HF ₂ , ozone, mercury, hafnium, CRO _X , FO _X , AlO _X , HF _X , CF _X , CF ₄ , CF ₆ , CF ₈ , CF ₃ , CrOF, CrO ₂ F, CrO ₂ F ₂ , CrO ₂ , CrO, Cr, CrF ₂ , CrF, SiF ₄ , SiF, OF, O ₂ F, OF Consisting of ₂ , Al, AlO, Al ₂ O, Al ₂ O ₂ , AlF, AlF ₂ , N, N ₂ , N _X , C, C ₂ , C _X , H, H ₂ , H _X , O and O _X And X is an integer from 3 to 16, wherein the excimer or molecular fluorine laser is operated. In an excimer or molecular fluorine laser, the laser is: A discharge chamber initially filled with a gas mixture comprising an active rare gas, a halogen-containing species, a buffer gas, and a small amount of the first gas adduct and a small amount of the second gas adduct; A plurality of electrodes in the discharge chamber connected to a discharge circuit for energizing the gas mixture; An excimer or molecular fluorine laser, comprising a resonator surrounding said discharge chamber to produce an output laser line. 97. The excimer or molecular fluorine laser of claim 96, wherein the first gas adduct is xenon. 98. An excimer or molecular fluorine laser according to claim 97, wherein said second gas adduct is oxygen. 97. The excimer of claim 96, wherein the concentration of the first gas adduct is adjusted to control at least one of energy overshoot and energy stability, and the concentration of the second gas adduct is adjusted to control the output energy. Mercer or molecular fluorine laser. 98. The excimer or molecular fluorine laser of claim 96, wherein the concentrations of the first and second gas adducts are adjusted to control at least one of energy overshoot, energy stability, and output energy. In an excimer or molecular fluorine laser, the laser is: A discharge chamber initially filled with an active rare gas and a gas mixture comprising less than 0.1% fluorine, a buffer gas and a small amount of gas adduct; A plurality of electrodes in the discharge chamber connected to a discharge circuit for energizing the gas mixture; A resonator surrounding the discharge chamber to produce an output laser line, wherein the fluorine concentration is less than the concentration causing the maximum laser output energy, and the concentration of the small amount of gas adduct to compensate for the reduced output energy. Excimer or molecular fluorine laser, characterized in that selected. 102. The excimer or molecular fluorine laser of claim 101, wherein the fluorine concentration is 0.08% or less. 103. The excimer or molecular fluorine laser of claim 101 or 102, wherein the gas adduct is xenon. Claims 1 or 3 or 5 or 10 or 23 or 23 or 24 or 26 or 30 or 32 or 37 or 50 or 51 or 51 or 53 59. The laser according to any one of claims 57 to 58, wherein the laser is operated at a repetition rate of 1 kHz or higher. 107. The laser of claim 104, wherein the laser is operated at a repetition rate of 4 kHz or higher. 44. The system of claim 16 or 43, wherein the laser is operated at a repetition rate of 1 kHz or higher. 107. The system of claim 106, wherein the laser is operated at a repetition rate of 4 kHz or higher.