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. 12, 1999
Filed:
Sep. 20, 1996
M Salleh Ismail, Moorpark, CA (US);
Kavlico Corporation, Moorpark, CA (US);
Abstract
A multiple LOCOS (local oxidation) process shapes a surface of a substrate to form a series of planar regions which are vertically separated from each other. One exemplary process forms a hard mask layer for each LOCOS operation. Another exemplary process includes forming a silicon nitride mask layer and repeatedly changing the pattern of that mask layer. Each change in the pattern corresponds to a planar region to be formed; and after each change, oxide is grown in openings through the mask layer. The growth of oxide consumes part of the substrate and provides a vertical separation between the planar level corresponding to the pattern and a next higher planar level. Regions of the substrate once exposed by a mask pattern can remain exposed so that subsequent LOCOS operations maintain previously established separations between levels. A hard mask layer can include a polysilicon layer which protect a silicon nitride layer from conversion to oxide during the repeated LOCOS operations.