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. 16, 2001
Filed:
Sep. 08, 1999
Michihiko Yanagisawa, Ayase, JP;
Takeshi Sadohara, Ayase, JP;
SpeedFam-IPEC Co., Ltd., Ayase, JP;
Abstract
A wafer flattening process for improving the micro-roughness of a wafer by local etching while maintaining a distance between a plasma discharge location and the wafer surface at a predetermined value. By executing a plasma generating step, SF,gas in a gas cylinder,is fed to the inside of an alumina discharge tube,then plasma discharge of the SF,gas is caused by a plasma generator,to produce an activated species gas G and which is locally sprayed from a nozzle portion,of the alumina discharge tube,to the surface of the silicon wafer W. In this state, by performing a local etching step, the surface of the silicon wafer W is flattened. At this time, the distance from the approximate center of the plasma discharge location to the surface of the silicon wafer W is set to a distance larger than 3000 times the mean free path of the ions in the activated species gas G and smaller than 6000 times. Due to this, the ions in the activated species gas G are extinguished before being sprayed from the nozzle portion,and therefore the surface of the silicon wafer W is etched by only the neutral radicals without being damaged.