The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 24, 2001
Filed:
Feb. 20, 1998
Masashi Mizuno, Osaka, JP;
Masuo Tada, Osaka, JP;
Norio Yamazaki, Osaka, JP;
Takaaki Fukumoto, Tokyo, JP;
Other;
Abstract
Super clean air having therein chemical components—such as hydrocarbons, organic halogens, acidic gases, basic gases, aldehydes, nitrogen oxides, and H,O (that is, all components other than oxygen, nitrogen, and noble gases—the types of chemical components differ depending on the source of the air)—in concentrations no more than 1 ppb and a dew point lower than −40° C., is obtained from the atmosphere by low-temperature adsorption treatment in stages at temperatures ranging from −40° C. to −180° C. Material air collected from the atmosphere is pretreated in a room-temperature adsorption step to remove moisture and carbon dioxide. The pretreated air is then low-temperature adsorption treated by absorbents in a plurality of steps to adsorb the gaseous chemical components, the treatment temperature being lower in each succeeding step. Treatment at −40° C. may remove, for example, HF, SO,, and/or NH,. Treatment at −100° C. may remove, for example, SF,, C,F,, H,S, and/or N,O. Treatment at −150° C. may remove, for example, CF,, NO, CH,, and/or CO. The last treatment step produces super clean air suitable for use in processing semiconductor wafers.