Abstract:
The present invention relates to a system for recirculating the gas atmosphere within an excimer laser system, where contaminates, created in the laser&#39;s operation, are removed, and the gas concentrations of additive gases, such as Xe, Kr, or others, depleted in the laser operation, are rebalanced to specific lazing mixtures by analyzation and component replenishment from one or more external supplies.

Description:
CROSS REFERENCE TO OTHER APPLICATIONS 
       [0001]    This application claims benefit of priority to U.S. Provisional Application No. 62/209,330, filed Aug. 24, 2015, and U.S. Provisional Application No. 62/335,900, filed May 13, 2016 the disclosures of which are fully incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention pertains to, but is not limited to, a system for recirculating the gas atmosphere within an excimer laser system, where contaminates, created in the laser&#39;s operation, are removed, and the gas concentrations of additive gases, such as krypton (Kr), xenon (Xe), or others, depleted in the laser operation, are rebalanced to specified lazing mixture concentrations by analyzation and component replenishment from one or more external supplies. This system prevents the loss of significant amounts of the laser gas mixtures, which is important since gases such as Neon (Ne), which can account for approximately 97 percent of the laser gas mixture, are and expensive due to shortages, and lost once vented. 
         [0004]    2. Description of the State of the Art 
         [0005]    Excimer lasers are pulsed gas discharge lasers which produce optical output in the ultraviolet region of the spectrum. There are four commonly used excimer wavelengths which are dependent upon the active gas fill of the laser, the four wavelengths are: 
         [0000]    
       
         
               
               
               
             
               
               
               
             
           
               
                   
               
               
                 Wavelength 
                 Active Gas 
                 Relative Power 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 193 nm 
                 Argon Fluoride (ArF) 
                 60 
               
               
                 248 nm 
                 Krypton Fluoride (KrF) 
                 100 
               
               
                 308 nm 
                 Xenon Chloride (XeCl) 
                 50 
               
               
                 351 nm 
                 Xenon Fluoride (XeF) 
                 45 
               
               
                   
               
             
          
         
       
     
         [0006]    An excimer lasers are now commonly used in the production of microelectronic devices (semiconductor integrated circuits or “chips”), eye surgery, and micromachining. To operate efficiently, excimer lasers require three or more part, mixtures of rare high-purity noble gases such as krypton (Kr), xenon (Xe), or argon (Ar), and consequently the operation of an excimer laser is expensive. In addition to using rare high-purity noble gases a highly reactive halogen gas, such as, fluorine (F), or chlorine (Cl), apart from helium (He) and/or neon (Ne) as buffer gas, is further utilized. Since such small amounts of Xe are used, and there is a tremendous supply of Ar, there is no concern for recovery for these gases. Furthermore, the buffer gas is the primary gas in the lasing mixture, accounting for up to 99% by weight. The buffer gas also has to be chemically resistant in the excimer lasing gas chamber, as the halogenated gases, such as F 2  and Cl 2 , will react with just about any elements and/or molecules when atomized in the excimer lasing gas chamber. The choices for the buffer gas are He or Ne, and since He has a limited supply and is not recoverable once released to the atmosphere, Ne is the predominant buffer gas used in excimer lasers. With the growing amount of excimer lasers use in the world, there is a concern for Ne shortages, therefore the price of this noble gas has increased dramatically, and the growing need for lasing gas recovery. These gaseous components, and possibly other gases, are contained within a pressure vessel provided with longitudinally extending lasing electrodes for inducing a transverse electrical discharge in the gases. The discharge causes the formation of excited rare gas-halide molecules whose disassociation results in the emission of ultraviolet photons constituting the laser light. During operation, the halogen gas component reacts with materials inside the laser, such as, C, H, and is depleted from the gas mixture requiring periodic replacement. Halogen depletion coincides with the formation of impurities within the laser chamber, which impairs laser operation reducing the laser output power. 
         [0007]    In order to maintain a constant power from the laser, the voltage applied to the laser&#39;s electrodes can be increased to overcome the reduction in output power caused by the contaminants and the depleted halogen. Unfortunately, the higher voltages lead to a more rapid deterioration of the electrode materials in the laser, and a large increase in maintenance costs. A portion of the laser output energy can be recovered by simply replacing the depleted halogen in the laser chamber; however, without a means to remove the impurities, the laser gas mixture must be eventually replaced to return the laser back to full output. 
         [0008]    Accordingly, a significant portion of the operating cost of an excimer laser is therefore related to the contamination of costly, high-purity, noble gases. Over the years many of the challenges associated with excimer lasers have been mitigated through the use of corrosion-resistant materials, advanced gas recirculating and purification systems, and solid-state high-voltage switches. These continued engineering improvements and rise of applications continue to exert a high demand on rare high-purity noble gases. For example, it has recently been demonstrated that a very narrow band pulse excimer laser capable of producing pulses at a rate in the range of about 500 to 2000 Hz with enhanced energy dose control and reproducibility can be achieved by adding small quantities of a laser enhancer consisting of oxygen or a heavy noble gas (xenon or radon for KrF lasers, or krypton, xenon or radon for ArF lasers) to the gas mixture. Tests demonstrated improved performance for the ArF lasers with the addition of about 6-10 ppm of Xe or 40 ppm of Kr. 
         [0009]    Accordingly, an improved system for reclaiming, rebalancing and recirculating rare high-purity noble gases and specifically xenon, is needed to ensure a continued supply of these gases at acceptable prices. An object of the present invention is to overcome the shortcomings of the prior art by providing an apparatus and method, which incorporates a unique change to the design concept of an excimer laser, whereby the expensive noble gases are reclaimed, rebalanced and recirculated while removing the impurities developed during operation of the excimer laser. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    The present invention relates to a system for recirculating the gas atmosphere within an excimer laser system, where contaminates, created in the laser&#39;s operation, are removed, and the gas concentrations of additive gases, such as Xe, Kr, or others, depleted in the laser operation, are rebalanced to specific lazing mixtures by analyzation and component replenishment from one or more external supplies. 
         [0011]    In lieu of analyzation, certain embodiments may be required to remove all of the lazing enhancing gas, such as xenon, before component replenishment. This may be achieved by, but not limited to, adsorption by transitional metals, adsorption by high surface area zeolite, alumina, and/or carbon, temperature swing adsorption, pressure swing adsorption. The lasing gas will be rebalanced to specific lazing mixtures with component replenishment from one or more external supplies. 
         [0012]    Another embodiment may result in the removal of all lazing gas enhancers and partial removal of noble lazing gases, and isolating the buffer gas, by means of, but not limited to, temperature swing adsorption, pressure swing adoption, membrane separation. The noble lasing gas enhancer will be rebalanced to specific lazing mixtures by analyzation and component replenishment from one or more external supplies. 
         [0013]    Another embodiment may result in the removal of all lazing gas enhancers and noble lazing gases, and isolating the buffer gas, by means of, but not limited to, temperature swing adsorption, pressure swing adoption, membrane separation. The noble lasing gas and lasing gas enhancer will be rebalanced to specific lazing mixtures with component replenishment from one or more external supplies. 
         [0014]    Another embodiment of the present invention contemplates measuring the lasing intensity and doping in the lasing enhancing gas back into the laser chamber as the lasing intensity decreases. For each of the methods disclosed, component replenishment will be blended to specified lasing mixture from one or more external supplies. 
         [0015]    Additional embodiments and features are set forth in the description that follows, and in part will become apparent to those skilled in the art upon examination of the specification or may be learned by the practice of the disclosed embodiments. The features and advantages of the disclosed embodiments may be realized and attained by means of the instrumentalities, combinations, and methods described in the specification. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    A further understanding of the nature and advantages of the disclosed embodiments may be realized by reference to the remaining portions of the specification and the drawings. 
           [0017]      FIG. 1  is a schematic diagram illustrating the configuration of an excimer laser system for analyzing the levels of a lazing enhancing gas present within a gas purification system and the eventual reclamation, rebalancing, and recirculation of the lasing enhancing gas in accordance with one embodiment of the invention; 
           [0018]      FIG. 2  is a schematic diagram illustrating the configuration of an excimer laser system for the removal of all lazing enhancing gas present within a gas purification system and the reclamation, rebalancing and recirculation of the lasing enhancing gas in accordance with one embodiment of the invention; 
           [0019]      FIG. 3  is a schematic diagram illustrating the configuration of an excimer laser system for the removal of all lazing enhancing gas and partial removal of noble lasing gas present within a gas analyzation and purification system arranged in accordance with one embodiment of the invention; and 
           [0020]      FIG. 4  is a schematic diagram illustrating the configuration of an excimer laser system for the removal of all noble lasing gas and lasing enhancing gas present within a gas analyzation and purification system arranged in accordance with one embodiment of the invention. 
           [0021]      FIG. 5  is a schematic diagram illustrating the configuration of an excimer laser system having the enhancing gas introduced into the tri-mix to enhance and simplify the recirculation system arranged in accordance with one embodiment of the invention. 
           [0022]      FIG. 6  is a schematic diagram illustrating the configuration of an excimer laser system having the enhancing gas introduced into the tri-mix to enhance and simplify the recirculation system arranged in accordance with one embodiment of the invention. 
           [0023]      FIG. 7  is a schematic diagram illustrating the configuration of an excimer laser system having the enhancing gas introduced into the tri-mix to enhance and simplify the recirculation system arranged in accordance with one embodiment of the invention. 
       
    
    
       [0024]    In the appended figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is listed in the specification, the description is applicable to anyone of the similar components having the same first reference label irrespective of the second reference label. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    With reference to  FIG. 1 , the system  100  for reclaiming, rebalancing and recirculating a laser enhancing gas according to one embodiment of the present invention is described. The laser chamber  20  is a vessel having one or two compartments, designed to hold several atmospheres of corrosive gases. These compartments are designed to known safety standards, such as those specified by ASME. The initial fill of the chamber is directed by control processor C. When initially filling the lasing gases in the laser chamber  20 , the laser chamber  20  is first evacuated using the gas recirculation pump, not shown, either via input port  18  or output port  22 . The laser chamber  20  is then filled to near the final fill pressure (for example 3000 to 5000 mBar or 40 to 72 psig) using a supply of the lasing gas mixture from a bi-mix or tri-mix gas cylinder  5  and  10  respectively. The supply can be a bi-mix containing only the noble, enhancing gas and gases in the correct ratio, which is approximately 1-5% Ar, 94-98% Ne and 1-100 ppm Xe and preferably 3.5 Ar, 95.5% Ne and 10 ppm Xe which can then be supplemented with halogen from the tri-mix gas cylinder  10  containing the noble, buffer and halogen gases in the proper ratio which is approximately 1-5% Ar, 75-99% Ne, 0.05-20% F 2  and preferably 3.5% Ar, 95.5% Ne and 1% F 2 . The operational discussion that follows is based on a laser chamber  20  having two compartments each of which are filled with the same gases to respected pressures (operate under similar but different pressures). Both lasing compartments operate at the same time and operate while partial gas is being exhausted and refilled. The lasers from both compartments are optically combined for enhancement over one source. 
         [0026]    Once the laser chamber  20  is filled with the halogen-rich laser gas mixture from original source gas cylinders  5  and  10 , and before operation of the laser  20  begins, the original source gas cylinders  5  and  10  are shut off, e.g. via valves  9  and  14  respectively. While the process can be performed manually it is preferably accomplished automatically under the control of a control processor C which is in electronic communication with each valve and each electrical component in the system of the present invention. 
         [0027]    During normal operation of the laser chamber  20 , the halogen and enhancing gases are possibly consumed, therefore, at a set period of time, typically between 1 and five minutes under maximum laser use, and preferably between two to three minutes and most preferably every 2 and one-half minutes, control processor C switches between the compartments while being used and partially exhausts and refills the compartment before performing the same function on the other compartment. The lasing gases having been exhausted are directed through outlet port  22  and passed through scrubber  30 , via pressure valve  24  to remove or abate the reactive gases present including the halogen gas required for operation of the laser chamber  20 . Scrubber  30  is a vessel formed from a suitable material such as stainless steel or nickel and typically contains activated alumina or activated charcoal to scrub the exhausted gases. 
         [0028]    Following exhaustion of the used compartment within laser chamber  20  pressure valve  24  is closed, thereby isolating the reclamation, rebalancing and recirculation system of the present invention from the laser chamber  20 , and the used compartment is then refilled using gases from original source cylinders  5  an  10 . After flowing the exhausted lasing gases through the scrubber  30 , the reactive or halogen gases initially present within the exhausted lasing gases will be present at levels less than 1 ppm. The scrubbed gases, now free of the reactive halogen, are next pressurized using compressor  40  and flow to a purifier  50  via valve  42 . Purifier  50  may be a single purifier or a purifier train  50  depending on the contaminants that are present in the scrubbed gas. The scrubbed gas may then flow through a second purifier that absorbs moisture, (order of purifiers may be reversed), followed by an additional purifier that removes submicron particles. One or more of the purifiers used may be regenerable. 
         [0029]    Exiting the gas purifier train  50 , via valve  52  impurities have been reduced from about 100 to 500 ppm to about 1 to 500 ppb levels, the halogen gas has been removed and the noble gases and enhancing gases are flowed into one of two cylinders  60  or  65  where the gas content is analyzed. In the first instance, the purified gas is flowed into cylinder  60  via valve  54 . Once cylinder  60  is filled vale  54  closes and valve  56  opens allowing purified gas to be directed into cylinder  65 . The purified gas within cylinder  60  is analyzed, by analyzer A, and the concentration of the noble gas, buffer and enhancing gas are determined. Analyzer A, then communicates via the control processor C and valves  62  and  82  will open thereby allowing the analyzed gas to be drawn out of cylinder  60  and the doping gases from cylinder  75 . Blender B will adjust the flow rates of these two streams of gases to form a rebalanced bi-mix containing only the noble, enhancing gas and buffer gases in the correct ratio that are reflective of that found in original source cylinder  5  and valves  62  and  82  are then closed. This rebalanced bi-mix then flows into cylinder  80  where the rebalanced bi-mix accumulates. Once the analyzed gas in cylinder  60  is removed valves  62  and  56  will shut, valve  67  will open and the purified gas contained within cylinder  65  will be analyzed while cylinder  60  is filling as a result of valve  54  opening. This batch analysis of the purified gases in cylinders  60  and  65  will continue to cycle while the laser system is operating. 
         [0030]    The rebalanced bi-mix gases will continue to accumulate in cylinder  80  until a predetermined pressure is reached where upon valve  83  will open and compressor  85  will pressurize the bi-mix and this recycled bi-mix will be stored in cylinder  90  at a concentration that is equivalent to that of the original source bi-mix stored in cylinder  5 . When laser chamber  20  requires a new supply of gas, the tri-mix in original source cylinder  10  will continue to serve as the source of the halogen gas; however, the recycled bi-mix stored in cylinder  90  will be available to fill the compartments within the laser chamber  20  when a predetermined pressure is reached at pressure transducer  92 , valve  9  (connected to original source cylinder  5 ) will be turned off and valve  12  turned on, resulting in the laser chamber  20  being filled using the recycled bi-mix gas stored in cylinder  90 . Thus, the system of the present invention provides a method for reclaiming the noble buffer gas used in an excimer laser and producing a recycled bi-mix mixture that can be substituted for the original bi-mix gases, thereby conserving the noble buffer gas and controlling the costs associated therewith. The system of the present invention also provides for the recycling of or the reintroduction of the noble enhancing gas. 
         [0031]    In an alternate embodiment illustrated in  FIG. 2 , a purifier  251  for the removal of the enhancing gas is added to the purifying train  250 . Purifier  251  may be achieved by but is not limited to, adsorption by transitional metals, adsorption by high surface area zeolite, alumina, and/or carbon, temperature swing adsorption, pressure swing adsorption. In this particular embodiment since the enhancing gas has been removed it is not necessary to analyze the purified gas to determine the concentration of the enhancing gas as it was in the previous embodiment described in  FIG. 1 . Since the lasing and buffer gases are not consumed, control processor opens both valves  252  and  282 . The purified gas flowing through valve  252  and the doping gas pulled from cylinder  275  are then blended by blender B. Blender B adjusts the flow rates of these two streams of gases to form a rebalanced bi-mix containing only the noble, enhancing and buffer gases in the correct ratio that are reflective of that found in the original source cylinder  205 . This rebalanced bi-mix then flows into cylinder  280  where the rebalanced bi-mix accumulates. 
         [0032]    The rebalanced bi-mix gases will continue to accumulate in cylinder  280  until a predetermined pressure is reached where upon valve  283  will open and compressor  285  will pressurize the recycled bi-mix and this recycled bi-mix will be stored in cylinder  290  at a concentration that is equivalent to that of the original source bi-mix stored in cylinder  205 . The recycled bi-mix stored in cylinder  290  will be available to fill the compartments within the laser chamber  220  when a predetermined pressure is reached at pressure transducer  292 , valve  209  (connected to original source cylinder  205 ) will be turned off and the laser chamber  220  will be filled using the recycled bi-mix gas stored in cylinder  290 . Eventually, purifier  251  will be regenerated and the enhancing gas released will be vented. 
         [0033]    An alternative embodiment recognizes that the purifier  251 , as described in  FIG. 2 , will remove the enhancing gas and may partially remove the noble lasing gases as in  FIG. 1  there exists a process for analyzing the purified gas in order to determine the concentrations of the bi-mix constituents so that the correct amount may be doped back in to form a recycled bi-mix. As illustrated in  FIG. 3 , purifier  351  is added to the purifying train  350  for the removal of the enhancing gas and partial removal of the lasing gas. Purifier  351  may be, but is not limited to, a means for the removal of the enhancing gas and partial removal of lasing gas by way of an adsorption by transitional metals, adsorption by high surface area zeolite, alumina, and/or carbon, temperature swing adsorption, pressure swing adsorption. Exiting the gas purifier train  350 , via valve  352  impurities have been reduced from about 100 to 500 ppm to about 1 to 500 ppb levels, the halogen gas has been removed and the noble lasing gases, and enhancing gases have also been reduced. It is important to note that the purifier train  350  and purifier  351  will have very limited to no effect on the buffer gas and therefore the buffer gas will be largely reclaimed. The purified gas will now flow into one of two cylinders  360  or  365  where the gas content is analyzed. In the first instance, the purified gas is flowed into cylinder  360  via valve  354 . Once cylinder  360  is filled valve  354  closes and valve  356  opens allowing purified gas to be directed into cylinder  365 . The purified gas within cylinder  360  is analyzed, by analyzer A, and the concentration of one or more of the noble gas, noble buffer or noble enhancing gas are determined. Analyzer A, then communicates via the control processor C and valves  362  and  382  will open thereby allowing the analyzed gas to be drawn out of cylinder  360  and the doping gases from cylinder  375 . Blender B will adjust the flow rates of these two streams of gases to form a rebalanced bi-mix containing only the noble, enhancing gas and buffer gases in the correct ratio that are reflective of that found in the original source cylinder  305 . This rebalanced bi-mix then flows into cylinder  380  where the rebalanced bi-mix accumulates. Once the analyzed gas in cylinder  360  is removed valves  362  and  356  will shut, valve  354  will open and the purified gas contained within cylinder  365  will be analyzed while cylinder  360  is filling. This batch analysis of the purified gases in cylinders  360  and  365  will continue to cycle while the laser system is operating. 
         [0034]    The rebalanced bi-mix gases will continue to accumulate in cylinder  380  until a predetermined pressure is reached where upon valve  383  will open and compressor  385  will pressurize the recycled bi-mix and this recycled bi-mix will be stored in cylinder  390  at a concentration that is equivalent to that of the original source bi-mix stored in cylinder  305 . The recycled bi-mix stored in cylinder  390  will be available to fill the compartments within the laser chamber  320  when a predetermined pressure is reached at pressure transducer  392  valve  309  (connected to original source cylinder  205 ) will be turned off, valve  312  turned on and the laser chamber  320  will be filled using the recycled bi-mix gas stored in cylinder  390 . Eventually, purifier  351  will be regenerated to continue to remove impurities. 
         [0035]    In an alternative embodiment, illustrated in  FIG. 4 , all of the lasing gas as well as all of the enhancing gas is removed from the purified gas and therefor it is not necessary to analyze the content of the gas leaving purifier  451 . The buffer gas being lighter than the lasing and enhancing gases will not be removed to an appreciable extent by the purifiers and therefore, this rare material will be reclaimed. Again, as discussed previously, purifier  451  may be achieved by, but is not limited to, the use of: adsorption by transitional metals, adsorption by high surface area zeolite, alumina, and/or carbon, temperature swing adsorption, pressure swing adsorption. In this particular embodiment since both the lasing and enhancing gases have been removed it is not necessary to analyze the purified gas to determine the concentration of the lasing and enhancing gases as it was in the previous embodiment described in  FIG. 3 . Since the buffer gas is not consumed, control processor opens both valves  452  and  482 . The purified gas, which should at this point be essentially buffer gas will flow through valve  452  and the doping gas pulled from cylinder  475  are then blended by blender B. Blender B adjusts the flow rates of these two streams of gases to form a rebalanced bi-mix containing only the noble, enhancing and buffer gases in the correct ratio that are reflective of that found in the original source cylinder  405 . This rebalanced bi-mix then flows into cylinder  480  where the rebalanced bi-mix accumulates. 
         [0036]    The rebalanced bi-mix gases will continue to accumulate in cylinder  480  until a predetermined pressure is reached where upon valve  483  will open and compressor  485  will pressurize the recycled bi-mix and this recycled bi-mix will be stored in cylinder  490  at a concentration that is equivalent to that of the original source bi-mix stored in cylinder  205 . The recycled bi-mix stored in cylinder  290  will be available to fill the compartments within the laser chamber  420  when a predetermined pressure is reached at pressure transducer  492  valve  409  (connected to original source cylinder  405 ) will be turned off and the laser chamber  420  will be filled using the recycled bi-mix gas stored in cylinder  490 . Eventually, purifier  451  will be regenerated to continue to remove impurities. 
         [0037]    As discussed in detail above and shown in  FIG. 1 , when initially filling the lasing gases in the laser chamber  20 , the laser chamber  20  is first evacuated using the gas recirculation pump, not shown, either via input port  18  or output port  22 . The laser chamber  20  is then filled to near the final fill pressure (for example 3000 to 5000 mBar or 40 to 72 psig) using a supply of the lasing gas mixture from a bi-mix or tri-mix gas cylinder  5  and  10  respectively. Traditionally, the house supply is a bi-mix containing only the noble, buffer gas, and enhancing gas in the correct ratio, which is approximately 1-5% Ar, 94-98% Ne and 1-100 ppm Xe, respectively and preferably 3.5% Ar, 95.5% Ne and 10 ppm Xe, respectively which can then be supplemented with halogen from the tri-mix gas cylinder  10  containing the noble, buffer and halogen gases in the proper ratio which is approximately 1-5% Ar, 75-99% Ne, 0.05-20% F 2 , and preferably 3.5% Ar, 95.5% Ne and 1% F 2 . However, in the following alternative embodiment described below and shown in  FIG. 5 , the enhancing gas, Xe, is added to the tri-mix, forming a quad-mix, in the same amount as that found in the bi-mix. For example, if the bi-mix contains 10 ppm Xe then 10 ppm Xe would also be present in the quad-mix thereby eliminating the dilution of Xe that takes place when the standard bi-mix and tri-mix are combined. Use of the quad-mix formulation assures the user that the combination of the bi-mix and quad-mix in the chamber will never be diluted. Additionally, the quad-mix formulation could possibly eliminate any blending that is needed during recirculation, as discussed above in previous embodiments. 
         [0038]    As illustrated in  FIG. 5 , the house bi-mix gas which is approximately 1-5% Ar, 94-98% Ne and 1-100 ppm Xe and preferably 3.5% Ar, 95.5% Ne and 10 ppm Xe stored in cylinder  505  can then be supplemented with halogen from the quad-mix gas cylinder  510  containing the noble, buffer, halogen gases and the enhancing gas in the proper ratio which is approximately 1-5% Ar, 75-99% Ne, 0.05-20% F 2  and 1-100 ppm Xe; and preferably 3.5% Ar, 95.5% Ne, 1% F 2 , and Xe 10 ppm. Once the laser chamber  520  is filled with the halogen-rich laser gas mixture from original source gas cylinders  505  and  510 , and before operation of the laser  520  begins, the original source gas cylinders  505  and  510  are shut off, e.g. via valves  509  and  514  respectively. While the process can be performed manually it is preferably accomplished automatically under the control of a control processor C which is in electronic communication with each valve and each electrical component in the system of the present invention. 
         [0039]    During normal operation of the laser chamber  520 , the halogen is possibly consumed, therefore, at a set period of time, typically between 1 and five minutes under maximum laser use, and preferably between two to three minutes and most preferably every 2 and one-half minutes, control processor C switches between the compartments while being used and partially exhausts and refills the compartment before performing the same function on the other compartment. The lasing gases having been exhausted are directed through outlet port  522  and passed through scrubber  530 , via pressure valve  524  to remove or abate the reactive gases present including the halogen gas required for operation of the laser chamber  520 . Scrubber  530  is a vessel formed from a suitable material such as stainless steel or nickel and typically contains activated alumina or activated charcoal to scrub the exhausted gases. 
         [0040]    Following exhaustion of the used compartment within laser chamber  520  pressure valve  524  is closed, thereby isolating the reclamation, rebalancing and recirculation system of the present invention from the laser chamber  520 , and the used compartment is then refilled using gases from original house source cylinders  505  and  510 . After flowing the exhausted lasing gases through the scrubber  530 , the halogen gases initially present within the exhausted lasing gases will be present at levels less than 1 ppm. The scrubbed gases, now free of the reactive halogen, are next pressurized using compressor  540  and flow to a purifier  550  via valve  542 . Purifier  550  may be a single purifier or a purifier train  551  depending on the contaminants that are present in the scrubbed gas. The scrubbed gas may then flow through a second purifier that absorbs moisture, (order of purifiers may be reversed), followed by an additional purifier that removes submicron particles. One or more of the purifiers used may be regenerable. 
         [0041]    Again, as discussed previously, purifier  550  may be achieved by, but is not limited to, the use of: adsorption by transitional metals, adsorption by high surface area zeolite, alumina, and/or carbon, temperature swing adsorption, pressure swing adsorption. In this particular embodiment since the lasing gas has been removed it is not necessary to analyze the purified gas to determine the concentration of the enhancing gas as it was in the previous embodiment described in  FIG. 3 . Since the noble, buffer and enhancing gases are not consumed, control processor opens both valves  552  and  582 . The purified gas, which should at this point be essentially noble, buffer and enhancing gases will flow through valve  552  and flows into cylinder  580  where the rebalanced quad-mix accumulates. 
         [0042]    The rebalanced quad-mix gases will continue to accumulate in cylinder  580  until a predetermined pressure is reached where upon valve  583  will open and compressor  585  will pressurize the recycled bi-mix and this recycled bi-mix will be stored in cylinder  590  at a concentration that is equivalent to that of the original source bi-mix stored in cylinder  505 . The recycled bi-mix stored in cylinder  590  will be available to fill the compartments within the laser chamber  520  when a predetermined pressure is reached at pressure transducer  592  valve  509  (connected to original source cylinder  505 ) will be turned off and the laser chamber  520  will be filled using the recycled bi-mix gas stored in cylinder  590  in combination with the quad-mix stored in cylinder  510 . Eventually, purifier  551  will be regenerated to continue to remove impurities. 
         [0043]    In an alternative embodiment, as illustrated in  FIG. 6 , the house bi-mix gas cylinder is eliminated and the quad-mix gas cylinder  610  containing the noble, buffer, halogen gases and the enhancing gas in the proper ratio which is approximately 1-5% Ar, 75-99% Ne, 0.05-20% F 2 , and 1-100 ppm Xe; and preferably 3.5% Ar, 94.5% Ne, 1% F 2 , and Xe 10 ppm is initially used. Once the laser chamber  620  is filled with the halogen-rich laser gas mixture from original source gas cylinder  610 , and before operation of the laser  620  begins, the original source gas cylinder  610  is shut off, e.g. via valve  614 . While the process can be performed manually it is preferably accomplished automatically under the control of a control processor C which is in electronic communication with each valve and each electrical component in the system of the present invention. As discussed previously following exhaustion of the used compartment within laser chamber  620  pressure valve  624  is closed, thereby isolating the reclamation, rebalancing and recirculation system of the present invention from the laser chamber  620 , and the used compartment is then refilled using gases from original house source cylinder  610 . After flowing the exhausted lasing gases through the scrubber  630 , the halogen gases initially present within the exhausted lasing gases will be present at levels less than 1 ppm. The scrubbed gases, now free of the reactive halogen, are next pressurized using compressor  640  and flow to a purifier  650  via valve  642 . Purifier  650  may be a single purifier or a purifier train  651  depending on the contaminants that are present in the scrubbed gas. The scrubbed gas may then flow through a second purifier that absorbs moisture, (order of purifiers may be reversed), followed by an additional purifier that removes submicron particles. One or more of the purifiers used may be regenerable. 
         [0044]    Again, as discussed previously, purifier  651  may be achieved by, but is not limited to, the use of: adsorption by transitional metals, adsorption by high surface area zeolite, alumina, and/or carbon, temperature swing adsorption, pressure swing adsorption. In this particular embodiment since the lasing gas has been removed it is not necessary to analyze the purified gas to determine the concentration of the enhancing gas as it was in the previous embodiment described in  FIG. 3 . Since the noble, buffer and enhancing gases are not consumed, control processor opens both valves  652  and  656  and directs the gases into buffer cylinder  665 . Buffer cylinder  665  should contain the correct amount of noble, buffer, and enhancing gas, just needs 1% F 2 , 95.5% Ne, 3.5% Ar, and 10 ppm Xe to create, 0.1% F2, 96.4% Ne, 3.5% Ar, and 10 ppm Xe which is exactly what is needed in the laser with no blending at the laser, as in this embodiment we blend at the recycling system. Also, in this case the house quad-mix in cylinder  610  is 0.1% F2, 96.4% Ne, 3.5% Ar, and 10 ppm Xe. 
         [0045]    Afterwards the control processor opens both valves  667  and  682 . The purified gas, which should at this point be essentially noble, buffer and enhancing gases will flow through valve  667  and the doping gas, which is a 0.5-20% F 2  and preferably 1% F 2  pulled from cylinder  675 , through valve  682 , are then blended by blender B. Blender B adjusts the flow rates of these two streams of gases to form a rebalanced quad-mix in the correct ratio that are reflective of that found in the original source cylinder  610 . This rebalanced quad-mix then flows into cylinder  680  where the rebalanced quad-mix accumulates. 
         [0046]    The rebalanced bi-mix gases will continue to accumulate in cylinder  680  until a predetermined pressure is reached where upon valve  683  will open and compressor  685  will pressurize the recycled bi-mix and this recycled bi-mix will be stored in cylinder  690  at a concentration that is equivalent to that of the source quad-mix stored in cylinder  610 . The recycled bi-mix stored in cylinder  690  will be available to fill the compartments within the laser chamber  620  when a predetermined pressure is reached at pressure transducer  692  valve  614  (connected to cylinder  610 ) will be turned off and the laser chamber  620  will be filled using the recycled bi-mix gas stored in cylinder  690 . Eventually, purifier  651  will be regenerated to continue to remove impurities. 
         [0047]    In an alternative embodiment, shown in  FIG. 7 , reclamation, rebalancing, and recirculation of the lasing enhancing gas system  700  a quad-mix and a tri-mix is used as described previously and shown in  FIG. 6 ; however, instead of blending and doping fluorine back into the reclaimed tri-mix the tri-mix that accumulates in cylinder  790  is introduced into laser chamber along with the quad-mix from source cylinder  710 . 
         [0048]    An alternate embodiment to measure the concentration of the enhancing gas during normal operation of the laser chamber is disclosed below. An energy monitor and the control processor monitor one or more operating conditions e.g. output power, output energy, enhancing gas content of the laser, and adjust the input of enhancing gas, i.e. enhancing rich gas mixture, as the case may be, from a gas cylinder to ensure each monitored operating condition stays within a predetermined range or above a predetermined operating level. Thermopile or photodiode sensors can be used to measure optical power and/or energy of the laser. The enhancing gas concentration can be measured by any conventional meter particular to the specific enhancing gas. As the operating condition of the laser returns to nominal operating conditions, e.g. above a threshold level or within desired range, the control processor halts the input of enhancing gas. The mass flow controllers can be calibrated by monitoring the rate of rise of the pressure in the chamber during refills. This operation could be performed manually by the operator or the system could be programmed to perform this calibration automatically and periodically. Many techniques can be used for monitoring the enhancing gas concentration. For example, the operating current of a prior art voltage electrostatic precipitator is a function of the enhancing gas concentration. Other detectors arranged to measure the electrical impedance of the laser gas is indicative of the enhancing gas concentration. The thermal conductivity of the laser gas can be measured as an indication of enhancing gas concentration. Enhancing gas concentration can also be determined by optical absorption techniques, optical emission techniques and photo acoustic techniques. Electrochemical cells can also be used to monitor enhancing gas concentration. These cells are currently commercially available for measuring enhancing concentration at trace levels. 
         [0049]    While the invention has been described in detail herein in accord with certain preferred embodiments thereof, many modifications and changes therein may be effected by those skilled in the art. Persons skilled in the art will recognize that the principals discussed above with respect to ArF excimer lasers will apply equally well to KrF excimer lasers. Persons skilled in the art of excimer laser design will also recognize that the feedback control system could be used to purposely vary the enhancing gas concentration on a substantially real time basis either for the purpose of producing a laser beam having a time variation or for the purpose of maintaining the beam parameters constant in which case the enhancing gas variation would be chosen to compensate for some effect which would otherwise have produced a time variation in the beam output. Accordingly, it is intended by the appended claims to cover all such modifications and changes as fall within the true spirit and scope of the invention. 
         [0050]    Without further elaboration it is believed that one skilled in the art can, using the description set forth above, utilize the invention to its fullest extent. 
         [0051]    Having disclosed several embodiments, it will be recognized by those of skill in the art that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the disclosed embodiments. Additionally, a number of well known processes and elements have not been described in order to avoid unnecessarily obscuring the present invention. Accordingly, the above description should not be taken as limiting the scope of the invention. 
         [0052]    Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limits of that range is also specifically disclosed. Each smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in that stated range is encompassed. The upper and lower limits of these smaller ranges may independently be included or excluded in the range, and each range where either, neither or both limits are included in the smaller ranges is also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included. 
         [0053]    As used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a process” includes a plurality of such processes and reference to “the dielectric material” includes reference to one or more dielectric materials and equivalents thereof known to those skilled in the art, and so forth. 
         [0054]    Also, the words “comprise,” “comprising,” “include,” “including,” and “includes” when used in this specification and in the following claims are intended to specify the presence of stated features, integers, components, or steps, but they do not preclude the presence or addition of one or more other features, integers, components, steps, acts, or groups.