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:
Mar. 27, 2001
Filed:
Jul. 07, 1998
Sagie Tsadka, Yavne, IL;
Applied Materials, Inc., Santa Clara, CA (US);
Abstract
A process is provided for detecting small particles on wafer surfaces by irradiating the wafer surface with two light beams having a small difference in wavelength, collecting the light scattered by the wafer in at least one direction, separating the collected light into two component beams having the wavelengths of the irradiating beams, and comparing the intensities of the two component beams. The intensities of the component beams are transduced to digital signals which are fed to a comparator. An apparatus is also provided which comprises a stage for supporting a wafer, laser source and optics for generating two laser beams having different wavelengths, superimposing them and scanning the wafer with them, a sensor for sensing the light scattered by the wafer and separating it into two components having the said wavelengths, an A/D converter for generating digital signals corresponding to said components and a comparator for analyzing whether said signals indicate the presence of small particles.