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:
Jan. 13, 1998
Filed:
Mar. 29, 1996
Neil Benjamin, East Palo Alto, CA (US);
Seyed Jafar Jafarian-Tehrani, Fremont, CA (US);
Max Artusy, Saratoga, CA (US);
Lam Resarch Corporation, Fremont, CA (US);
Abstract
An r.f. excited vacuum plasma processor has a workpiece held in place by a monopolar or bipolar electrostatic chuck having an electrode that develops peak r.f. voltages over a wide amplitude range. A chuck DC power supply source is connected to the chuck. An r.f. peak detecting circuit coupled with the electrode is part of a circuit for controlling the DC voltage applied by the chuck power supply to the chuck. The control circuit supplies an unamplified replica of a DC voltage derived by the peak detecting circuit to the chuck DC power supply source via a DC circuit including only passive elements so the level of the DC voltage applied to the chuck varies in response to variations in the peak amplitude of the r.f. voltage. The peak detector includes at least several series connected diodes having electrodes polarized in the same direction or two stacks of series connected diodes. In one of the stacks, the diode electrodes are polarized in one direction and in the other stack the diode electrodes are polarized in the other direction. The diodes of the peak detecting circuit are arranged so the DC bias voltage supplied to the chuck and the peak value of the r.f. voltage developed at the electrode have the same order of magnitude.