Fluid handling – Systems – Multiple inlet with single outlet
Reexamination Certificate
2000-06-26
2003-08-26
Walton, George L. (Department: 3753)
Fluid handling
Systems
Multiple inlet with single outlet
C137S003000, C137S338000, C137S341000, C372S057000, C372S058000, C372S059000, C372S060000
Reexamination Certificate
active
06609540
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for supplying fluorine gas, which are used in supplying fluorine gas to an excimer laser chamber (hereinafter simply referred to as a “chamber”) of an excimer laser device or the like.
BACKGROUND OF THE INVENTION
With respect to techniques for supplying fluorine gas to the chamber of an excimer laser device, for example, JP-A-6-334241 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) describes a technique of using an apparatus comprising a gas bomb filled with fluorine gas, a bomb filled with a rare gas such as krypton, and a bomb filled with a buffer gas such as neon or helium, where out of the gas components forming the excimer laser gas, the fluorine gas and the rare gas each accounting for a small constitutional ratio in terms of gas concentration are supplied through a sub-chamber and the buffer gas having a large constitutional ratio in terms of gas concentration is supplied directly to the chamber. However, in the case of supplying fluorine gas from a gas bomb, the bomb must be housed in a bomb box apart from the excimer laser device to ensure safety and handleability because the bomb contains fluorine gas at a high pressure and the bomb is large and heavy. This is disadvantageous in that the size of the apparatus as a whole becomes very large and fluorine gas filled in the bomb is deteriorated during the long-term storage to impair laser properties of the excimer laser.
On the other hand, for example, International Patent Application No. 5-502981 describes a fluorine gas-generating means using a fluorine-occluding substance such as fluoronickel material in which fluorine is occluded. The fluorine-occluding substance generates fluorine gas by heating and controlling it to a predetermined temperature. Even at a relatively low controlling temperature, the necessary amount of fluorine gas can be generated and at the same time, the generation pressure is low, so that easy handling and high safety can be attained. Furthermore, the generating means can be reduced in the size and since the equilibrated and non-gasified fluorine is in the occluded state, deterioration scarcely occurs even in the long-term storage. However, the pressure of fluorine gas generated using such a fluorine generating means is generally lower than the pressure in the chamber of an operating excimer laser device, therefore, even if fluorine gas is efficiently removed in a practical temperature range, the fluorine gas cannot be introduced directly into the chamber of an operating excimer laser device except for the case where the gas exchange is performed after gas in the chamber is evacuated. To solve this problem, some proposals have been made with an attempt to enable the supply of fluorine gas generated by such a fluorine gas-generating means using a fluorine-occluding substance even at the operating time, to say nothing of the gas exchange time.
Of these, the above-described International Patent Application No. 5-502981 proposes a technique of circulating gas in the chamber by a pump, disposing the above-described fluorine gas-generating means such that it is connectable to the circulation path, and supplying fluorine gas together with the circulating gas to the chamber. JP-A-9-116214 proposes a technique of connecting a bomb of buffer gas such as Ne to the above-described fluorine gas-generating means and supplying the fluorine gas generated under compression of the buffer gas into the chamber. However, generation of fluorine gas using the fluorine-occluding substance cannot be always controlled in a constant and simple manner depending to the temperature and the like. Therefore, the above-described method or apparatus where the fluorine gas-generating means is directly connected to the path for gas supplied to the chamber has difficulty in supplying in a stable manner the necessary amount of fluorine gas with good precision. Moreover, a portion having a high fluorine gas concentration is partially and temporarily generated in the gas supplied to the chamber because fluorine gas in 100% concentration is generated from the fluorine-occluding substance, and this may cause adverse effect such as fluctuation of the laser properties.
On the other hand, U.S. Pat. No. 5,396,514 proposes a technique of introducing fluorine gas generated in the above-described fluorine gas-generating means into a collecting receptacle and then connecting the collecting receptacle with the chamber to disperse the fluorine gas in the chamber, a technique of, similarly to the case in JP-A-9-116214 supra, connecting a rare gas bomb or the like to the collecting receptacle and simultaneously opening the valve between the rare gas bomb and the collecting receptacle and the valve between the collecting receptacle and the chamber to allow the rare gas or the like to compress the fluorine gas to flow out of the collecting receptacle into the chamber, or a technique of, similarly to the case of International Patent Application No. 5-502981 supra, circulating gas in the chamber and connecting the above-described collecting receptacle to the circulating path to thereby supply fluorine gas. However, in these methods or apparatuses, fluorine gas in 100% concentration or a gas unequal in fluorine gas concentration is still directly supplied to the chamber, therefore, the laser properties may fluctuate. This state that the laser properties are unstable disadvantageously continues for a long time particularly when fluorine gas is supplied by dispersion into the chamber, because it takes a long time for the fluorine gas to uniformly disperse in the chamber.
In the case of compressing fluorine gas in the fluorine gas-generating means or collecting receptacle by a buffer gas or rare gas to flow into the chamber, the fluorine gas concentration in the inflow gas is very difficult to always maintain at a predetermined concentration with good reproducibility. Therefore, the laser properties may fluctuate depending on supply of fluorine gas. In the case of circulating the gas in the chamber using a pump, compressor or circulating unit such as a blower and supplying fluorine gas to the circulation path, not only the problem of reproducibility or the like is present but also a problem arises that the fluorine gas supplying apparatus is inevitably complicated due to disposition of the circulating unit or a driving unit for driving it and the effect by using a fluorine-occluding substance in the fluorine gas-generating means is impaired.
On the other hand, in the method for supplying fluorine gas by using a sub-chamber described in JP-A-6-334241 or by using a collecting receptacle described in U.S. Pat. No. 5,396,514, the container is evacuated of residual gas whenever fluorine gas is supplied from the sub-chamber for the purpose of gas exchange in the chamber of an excimer laser device or addition of gas to the operating excimer laser device, and then receives fluorine gas from the fluorine gas-generating means in the container. This is disadvantageous not only due to the cumbersome operation but also in poor profitability, because the residual gas still contains fluorine gas in a certain concentration and also contains rare gas or buffer gas. Furthermore, in these methods or apparatuses for supplying fluorine gas, as a matter of course, fluorine gas cannot be introduced into the container while supplying fluorine gas from the container to the chamber. For example, if fluorine gas in the container runs short during the supply of fluorine gas to the chamber, the supply of fluorine gas must be once interrupted to again introduce fluorine gas into the container. Thus, the fluorine gas cannot be continuously supplied.
The present invention has been made under these circumstances.
SUMMARY OF THE INVENTION
A main object of the present invention is to provide a method and an apparatus for supplying fluorine gas when using the above-described fluorine-occluding substance for fluorine gas-generating means, in which a necessary amount of
Hoshino Yasuyuki
Nakagawa Shunzou
Sakai Yuji
Torisu Junichi
Yamazaki Mituyoshi
Showa Denko Kabushiki Kaisha
Walton George L.
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