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:
Sep. 02, 1997
Filed:
May. 09, 1996
Actel Corporation, Sunnyvale, CA (US);
Abstract
A method for fabricating the antifuse of the present invention comprises the steps of forming a lower antifuse electrode; forming a relatively thick interlayer dielectric layer over the surface of the lower antifuse electrode; forming a masking layer, preferably a photoresist, including an aperture therein having a first area over the interlayer dielectric layer; performing a first vertical etching step on the interlayer dielectric layer to a first selected depth; enlarging the aperture in the masking layer until it has a second area; performing a final vertical etching step on the interlayer dielectric layer to expose the upper surface of the lower electrode. Depending on the thickness of the interlayer dielectric, additional enlarging steps and vertical etching steps may be performed prior to the final vertical etching step which exposes the upper surface of the lower electrode. An aperture having a staircase profile is thereby formed, the aperture having a number of steps thus reducing and/or eliminating cusping and/or thinning at the corner and bottom of the antifuse cell opening allowing for the uniform deposit of dielectric and upper antifuse electrode materials.