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:
Mar. 13, 1990
Filed:
Mar. 17, 1988
Kimiaki Shimokawa, Tokyo, JP;
Hiroshi Hoga, Tokyo, JP;
Oki Electric Industry Co., Ltd., Tokyo, JP;
Abstract
An insulating film formed under a conductive film has a side wall defining a contact window and having the shape of a gently inclined curvilinear surface, so that the insulating film is able to provide a sufficient step coverage in the contact window. The insulating film is formed over the surface of a semiconductor substrate or a first conductive film. The insulating film has an increasing or decreasing refractive index over the depth thereof. A contact window is formed by selectively removing a portion of the insulating film using a photoresist pattern formed over the surface of the insulating film. A structure thus formed is subjected to an etching process capable of etching the upper layer of the insulating film at an etching rate higher than that for the lower layer of the same to etch the side wall of the insulating film defining the contact window into a gently inclined curvilinear surface, and then the photoresist pattern is removed. A second conductive film is formed over the surface of a structure formed in the preceding step.