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. 25, 2000
Filed:
Jun. 22, 1998
Applicant:
Inventors:
Hiroto Ohtake, Tokyo, JP;
Seiji Samukawa, Tokyo, JP;
Assignee:
NEC Corporation, Tokyo, JP;
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
C23F / ;
U.S. Cl.
CPC ...
216 70 ; 156345 ; 117 92 ; 117103 ; 117108 ; 118706 ; 1187 / ; 1187 / ; 1187 / ;
Abstract
The high-frequency electric field is subjected to pulse modulation for 10 to 100 .mu.sec; the rise time of pulse is controlled to be not shorter than 2 .mu.sec but not longer than 50 .mu.sec; and the descent time of pulse is controlled to be not shorter than 10 .mu.sec but not longer than .phi..mu.sec. Thereby, the electron temperature in plasma is controlled at 2 eV or lower and the fluctuation of the density of negative ion in plasma is controlled at 20% or smaller.