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. 19, 1977
Filed:
Sep. 22, 1975
Bohumil Polata, Los Altos, CA (US);
Signetics Corporation, Sunnyvale, CA (US);
Abstract
Defect formations and unwanted in diffusions caused by residual impurity products is prevented in a semiconductor fabrication method which includes the step of forming a composite mask which simultaneously defines base, collector and diffusion isolation openings. After these openings are defined a thin protective layer of silicon dioxide is grown over the exposed area and remains there throughout the remainder of the doping process which includes the steps of selectively covering areas which are not to be doped with photoresist and thereafter ashering the photoresist to remove it in preparation for the next ion implantation step. The thin protective layer of silicon dioxide protects nonselected areas against residual impurity products formed during removal of the photoresist.