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:
Jul. 17, 2001
Filed:
Jul. 16, 1998
Arun A. Aiyer, Fremont, CA (US);
Nikon Research Corporation of America, Belmont, CA (US);
Abstract
A CMP heterodyne in-situ sensor (C-HIS) system utilizes optical heterodyne interferometry. A wafer undergoing CMP is illuminated through the wafer thickness using an infrared laser beam at a wavelength of 1.1 &mgr;m or greater. The beam is transmitted through the wafer and is reflected from the front wafer surface. As the wafer is polished, the optical beam path through the wafer is shortened, causing the reflected optical frequency to undergo a Doppler shift. By measuring this shift, the change in wafer thickness is determined. The frequency shift generates a signal, which enables dynamic process control. In embodiments where the wafer includes a planarization film, the frequency shift provides a measurement of changing film thickness. Embodiments of the invention utilize phase detection independent of intensity, and hence do not suffer from intensity fluctuations. Some embodiments detect thickness changes less than 2.5 nm. C-HIS sensors operate in both polished-to-thickness and polished-to-stop scenarios.