Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture – Molecular oxygen or ozone component
Patent
1995-02-09
1997-08-12
Langel, Wayne
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
Molecular oxygen or ozone component
422171, 422177, 423351, 4232392, 438800, 62615, C01B 2100
Patent
active
056565577
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process and apparatus for producing and supplying high-purity nitrogen used in large amounts at semiconductor production factories, and purified air (high-purity air) and oxygen-rich air that can be effectively used in said factories.
BACKGROUND ART
Large amounts of high-purity nitrogen are conventionally used for various applications in the semiconductor industry. In investigation of the breakdown of these applications of high-purity nitrogen reveals that high-purity nitrogen is being used in a large amount in locations that do not necessarily require such. For example, although high-purity nitrogen gas is presently used for the sealing gas of pure water tanks used for washing semiconductors, in the case of not controlling the amount of dissolved oxygen, high-purity air of a prescribed purity is sufficient. Similarly, although high-purity nitrogen gas is also used for the bubbling gas for regeneration of an ion exchange resin for production of ultra-pure water, high-purity air of a prescribed purity can be used provided such air is able to be obtained.
In addition, although high-purity nitrogen is used in air guns and semiconductor substrate storage boxes used in various semiconductor production processes in order to avoid adherence of various types of impurities, such as hydrocarbons including oils and sulfur compounds including sulfur oxides (SO.sub.x) and the like, on semiconductor substrates (wafers), high-purity air can be used instead of this high-purity nitrogen if such impurities are removed from air. In addition, high-purity air can also be substituted for high-purity nitrogen used as the carrier gas in substrate transport systems such as Bernoulli chucks and air levitation conveyors in semiconductor production equipment.
Similarly, there are also several possible processes in which high-purity air can be used instead of high-purity nitrogen or high-purity oxygen currently used as a semiconductor material gas. For example, high-purity oxygen used as the diluent gas of material gases such as carbon tetrafluoride in the etching process can be substituted with high-purity air, while air can also be used instead of the high-purity nitrogen and high-purity oxygen used in the purging process of nonreducing gases, such as chlorine, hydrogen chloride and hydrogen bromide, used in semiconductor production processes, provided it has a prescribed purity.
In view of the above, attempts have been made to reduce costs by using high-purity air instead of expensive high-purity nitrogen and high-purity oxygen in various applications. The specifications of high-purity air when used in these applications are required to be such that the levels of hydrogen (H.sub.2), carbon monoxide (CO), methane (CH.sub.4 ; total hydrocarbons (THC) as methane), water (H.sub.2 O), carbon dioxide (CO.sub.2), nitrogen compounds (NO.sub.X) and sulfur compounds (SO.sub.x) and so forth are 1 ppm or less.
In addition, since there are many processes in the production of semiconductors that are maintained at constant temperature and constant humidity, such as equipment for obtaining constant temperature and constant humidity, e.g. for air conditioning and maintaining pure water temperature, their cost is a considerable amount. Consequently, these processes are considered for reducing costs. In general, steam is supplied from a boiler to serve as a heating source, and in the heating furnace for this boiler, heating is usually performed with a fuel oil/air burner. Thus, by replacing the air of this fuel oil/air burner with oxygen-rich air, it is possible to significantly increase the combustion efficiency of the heating furnace.
Moreover, although purified air, from which water and carbon dioxide have been removed, has been conventionally used for various instruments and sealing, such air has been supplied to accommodate a relatively small demand by compressing with a small compressor and so forth, and then purified with a purifier. In addition, air for instrumentation in air liquefaction
REFERENCES:
patent: 5441719 (1995-08-01), Nagamura et al.
Hata Yuichi
Kawamura Mamoru
Nakamura Maki
Okada Shuichi
Sasaki Jun
Langel Wayne
Nippon Sanso Corporation
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