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:
Jan. 09, 2001
Filed:
Jul. 16, 1999
Christopher S. Blair, San Jose, CA (US);
Weidong Chen, San Jose, CA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A process flow for forming a polysilicon-to-polysilicon capacitor performs the capacitor anneal step in a nitrous oxide ambient. As a result, a nitroxide layer forms over heavily doped polysilicon of the upper electrode of the capacitor. This nitroxide layer acts as a barrier against the diffusion of oxygen, preventing further oxidation of the heavily doped polysilicon electrode layer during the subsequent seal oxidation step. The nitroxide barrier layer is readily removed along with the other seal oxide layers immediately before formation of the silicided capacitor electrode contacts, without any attendant danger of overetching of gate oxide or spacer structures. Where the gate polysilicon layer is doped immediately after its formation, an additional capacitor anneal step in a nitrous oxide ambient is necessary to form an additional nitroxide layer.