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:
Feb. 19, 2008
Filed:
Jan. 20, 2004
Arne W. Ballantine, So. Burlington, VT (US);
Scott A. Estes, Essex Junction, VT (US);
Emily E. Fisch, Burlington, VT (US);
Gary Milo, Williston, VT (US);
Ronald A. Warren, Essex Junction, VT (US);
Arne W. Ballantine, So. Burlington, VT (US);
Scott A. Estes, Essex Junction, VT (US);
Emily E. Fisch, Burlington, VT (US);
Gary Milo, Williston, VT (US);
Ronald A. Warren, Essex Junction, VT (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
In a process using a hot phosphoric acid etchant () to etch silicon nitride on a semiconductor wafer () submerged in a tank () of the etchant (), a recirculating path is established for the etchant (). A porous filter () is coated with silicon nitride and installed in the recirculating path. As the etchant () in the recirculating path flows through the porous filter (), the silicon nitride on the porous filter () dissolves into the etchant (). In the tank (), the silicon nitride dissolved in the etchant () significantly suppresses the etch of silicon dioxide on the semiconductor wafer (), thereby enhancing the etch selectivity of the process. Monitoring and maintaining the concentration of the silicon nitride in the etchant () stabilizes the etch selectivity of the process.