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. 05, 2013
Filed:
Mar. 22, 2011
Yukihiro Utsuno, Fukushima-ken, JP;
Yukihiro Utsuno, Fukushima-ken, JP;
Spansion LLC, Sunnyvale, CA (US);
Abstract
A silicon nitride film, which is a second hard mask, is dry etched to be removed completely. The silicon nitride film, which is formed on a sidewall of a silicon nitride film used as a first hard mask, has a relatively low etching rate. Therefore, if the silicon nitride film is continued etching until the corresponding portion thereof is removed, polysilicon is etched in a direction of depth in trench shape. Then, floating gates in adjacent cells are separated and a step portion of the polysilicon is formed. Consequently, a remaining portion of the silicon nitride film used as the first hard mask is removed, an ONO film is laminated on a whole surface of the poly silicon having the step portion on an edge that has been etched, and then, a polysilicon for a control gate is laminated on the ONO film.