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:
Oct. 19, 1999
Filed:
Dec. 23, 1997
SGS-Thomson Microelectronics S.A., Saint Genis, FR;
Abstract
The present invention relates to a method of forming deep trenches in a BICMOS-type integrated circuit wherein the formation of a bipolar transistor includes the steps of depositing a base polysilicon layer, depositing a protection oxide layer, forming an emitter-base opening, and etching the silicon oxide protection layer and the base polysilicon layer outside the bipolar transistor areas. The formation of the trenches includes the steps of opening the protection oxide and base polysilicon layers above a thick oxide region while the emitter-base opening is being made, etching the thick oxide layer while the protection oxide layer is being etched, and etching the silicon under the thick oxide while the base polysilicon is being etched.