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. 20, 1990
Filed:
May. 06, 1988
Nan-Hsiung Tsai, Cupertino, CA (US);
MOS Electronics Corporation, Sunnyvale, CA (US);
Abstract
A method for forming substrate contacts in an integrated circuit structure uses a layer of conductive material, preferably polycrystalline silicon, applied to the surface of the semiconductor structure to make electrical contact with exposed portions of the substrate. The polycrystalline silicon layer is then coated with a nitride layer. A via mask which is opaque over the region where a contact will be formed produces a photoresist stud smaller that the original via mask. The photoresist stud is used to pattern the nitride to remain only over the contact region. Following this, the polycrystalline silicon is oxidized except at the nitride mask, forming a bird's beak beneath edges of the nitride. The resulting contact is smaller than the photolithographic limit of the via mask and thus allows for smaller space allocated for contact regions and smaller total structure.