Wet Etch End Point Determination Using Optical Character Regognition
Original Publication Date: 1989-Jan-01
Included in the Prior Art Database: 2005-Jan-27
This article addresses the determination of optimum developing times for resist images on semiconductor wafers exposed in step-and-repeat lithograpy using an E-beam or optical lithography tool. The disclosed process views the developed condition of a dose "wedge" contained on the wafer in real time and compares it to development of the lines imaged on the wafer by means of an optical monitoring system. The dose "wedge" has been employed as a development indicator in prior art. Optimum developing time can be a function of many variables: developer temperature, concentration and age; exposure time, intensity; etc. Existing approaches to this determination employ a send-ahead wafer to characterize the developer and then use the time so determined to process the remaining wafers.