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:
Sep. 26, 1995
Filed:
Mar. 09, 1994
Leszek Niewmierzycki, San Jose, CA (US);
Other;
Abstract
This invention teaches an apparatus and method for detection and correction of eccentricity and angular misalignment of a wafer. The position of a wafer is determined while the wafer is stationary on a robot arm by position sensors that locate four points on the periphery of the wafer. A microprocessor selects and uses a specific combination of three of the four points to calculate the actual location of the center of the wafer. The microprocessor produces signals which are used to correct the wafer's eccentricity using two rotatable shafts, an inner shaft mounted inside an outer shaft. The outer shaft is rotated prior to arrival of the wafer, in order to position the inner shaft at a pre-determined location depending on the eccentricity to be corrected. After the wafer is placed on a turntable mounted on and rotatable by the inner shaft, the inner shaft is rotated by the requisite angle to eliminate the wafer's eccentricity in a single movement. Optionally, to correct angular misalignment of the wafer, the outer shaft is rotated by the desired angle simultaneous with the inner shaft rotation. For process shifts, both eccentricity and angular misalignment are corrected in a single movement of the wafer.