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:
Oct. 13, 1998
Filed:
Jul. 02, 1997
Yoshio Ishihara, Tsukuba, JP;
Hiroshi Masusaki, Tsukuba, JP;
Shang-Qian Wu, Tsukuba, JP;
Koh Matsumoto, Tsukuba, JP;
Nippon Sanso Corporation, Tokyo, JP;
Abstract
A device and method for measuring an impurity in a trace concentration in a gas to be measured by infrared spectroscopic analysis employing a diode laser are provided. In order to carry out analysis with high sensitivity and high accuracy, the gas to be measured is directed into sample cell 5 and placed in a low pressure state by a pump 16. Infrared light from the wavelength region in which strong absorption peaks from the impurity can be obtained are oscillated from the diode laser 1, and a derivative absorption spectrum is measured by passing the infrared rays through sample cell 5 and reference cell 8 which is filled with the impurity alone. The spectrum for the gas to be measured and the spectrum for the impurity alone are compared, and the impurity is identified by confirming a plurality of absorption peaks originating from the impurity. Determination of the impurity is then carried out from absorption intensity of the strongest peak. In the case where molecules of the gaseous impurity form clusters in the gas to be measured, analysis is carried while dissociating the clusters by irradiating light having a photon energy of 0.5 eV or greater. The device and method are particularly suitable for carrying out analysis of trace quantities of impurities present in the gases which are used as materials for semiconductor manufacturing.