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:
Aug. 21, 1990
Filed:
Aug. 03, 1989
Holger Huebner, Baldham, DE;
Siemens Aktiengesellschaft, Berlin and Munich, DE;
Abstract
The apparatus includes a means for generating a magnetic field at a first electrode to which a high frequency voltage is applied and includes a generator for generating a rectangular low frequency voltage that is capacitively coupled to a second electrode which carries the substrate to be etched. The low frequency voltage comprises a negative half-wave having a short duration and a positive half-wave. The duration of the negative half-wave is selected to be shorter than a time constant for charging the substrate after a potential change corresponding to the amplitude of the half-wave and the positive half-wave is dimensioned so that the substrate remains free of charges on the average.