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. 07, 1986
Filed:
Mar. 15, 1985
Keiji Tada, Kudamatsu, JP;
Takashi Fujii, Kudamatsu, JP;
Gen Marumoto, Kudamatsu, JP;
Kazuhiro Jyouo, Kudamatsu, JP;
Takahiro Fujisawa, Yanai, JP;
Hitachi, Ltd., Tokyo, JP;
Hitachi Sanki Eng Co., Ltd., Tokyo, JP;
Abstract
The present invention relates to a method of and apparatus for detecting the end point of plasma treatment. The method includes steps: selecting a plasma spectrum having a characteristic wavelength from the plasma spectrum occurring at the time of the plasma treatment reaction of a specimen; computing a secondary differential value of a function of the quantity of the plasma spectrum selected and the plasma treatment reaction time of the specimen; and detecting the end point of the plasma treatment reaction of the specimen by comparing the secondary differential value computed with preset reference values for judgment. The apparatus comprises a means of selecting plasma spectrum having a particular wavelength from the plasma spectrum occurring at the time of the plasma treatment reaction of the specimen, a means of converting the quantity of the plasma spectrum selected into an analog electric signal, a means of converting the analog electric signal into a value of digital data, a means of counting the plasma treatment reaction time of the specimen, a means of secondarily differentiating a function of the value of digital data and the plasma treatment reaction time, a means of making judgment by comparing the secondary differential value with preset reference values for judgment, and a means of giving an instruction for starting judgment to said means. Thus, accurate detection is achieved regardless of which curve is taken by the change in the reaction time of the quantity of plasma spectrum.