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. 07, 2000
Filed:
Sep. 29, 1997
Krishnaswamy Ramkumar, San Jose, CA (US);
Pamela Trammel, San Jose, CA (US);
Sharmin Sadoughi, Cupertino, CA (US);
Cypress Semiconductor Corporation, San Jose, CA (US);
Abstract
A method of forming a field oxide or an isolation region in a semiconductor die. An oxidation mask layer (over an oxide layer disposed over the substrate) is patterned and subsequently etched, preferably so that the oxidation mask layer may have a nearly vertical sidewall. The oxide layer and the substrate in the isolation region are etched to form a recess in the substrate having a sloped surface with respect to the sidewall of the oxidation mask layer. A field oxide is then grown in the recess using a dry oxidizing atmosphere. The sloped sidewall of the substrate recess effectively moves the face of the exposed substrate away from the edge of the oxidation mask layer sidewall. Compared to non-sloped techniques, the oxidation appears to start with a built-in offset from the patterned etch. This leads to a reduction of oxide encroachment and less field oxide thinning. The preferred range of slopes for the substrate sidewall is from approximately 10.degree. to 40.degree. with respect to the oxidation mask layer sidewall.