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. 08, 2009
Filed:
Nov. 29, 2007
Mengyu Pan, Shanghai, CN;
Zengyi He, Shanghai, CN;
Kaiyu Chen, Shanghai, CN;
Alpha & Omega Semiconductor, Inc., Sunnyvale, CA (US);
Abstract
A method and device structure are disclosed for preventing gate oxide damage of a trench MOSFET during wafer processing while adding an ESD protection module atop the trench MOSFET. The ESD protection module has a low temperature oxide (LTO) bottom layer whose patterning process is found to cause the gate oxide damage. The method includes: a) Fabricate numerous trench MOSFETs on a wafer. b) Add a SiNisolation layer, capable of preventing the LTO patterning process from damaging the gate oxide, atop the wafer. c) Add numerous ESD protection modules atop the SiNisolation layer. d) Remove those portions of the SiNisolation layer that are not beneath the ESD protection modules. In one embodiment, hydrofluoric acid is used as a first etchant for patterning the LTO while hot phosphoric acid is used as a second etchant for removing portions of the SiNisolation layer.