Photolithography control system and method using latent image measurements
Patent 5338630 Issued on August 16, 1994. Estimated Expiration Date: 
November 18, 2013. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
November 18, 2013. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesPairwise comparison device Projection exposure apparatus Focus and overlay characterization and optimization for photolithographic exposure High resolution metal patterning of ultra-thin films on solid substrates High resolution patterning on solid substrates Patent #: 5079600 InventorsApplicationNo. 154603 filed on 11/18/1993US Classes:430/30, INCLUDING CONTROL FEATURE RESPONSIVE TO A TEST OR MEASUREMENT250/492.1, IRRADIATION OF OBJECTS OR MATERIAL250/492.2, Irradiation of semiconductor devices430/311, Making electrical device438/7, Optical characteristic sensed438/949Energy beam treating radiation resist on semiconductorExaminersPrimary: Kight, III, JohnAssistant: Mosley, Terressa Attorney, Agent or FirmInternational ClassesG03C 005/00H01L 021/00 G01R 031/26 AbstractA method of and apparatus for processing semiconductor wafers which include observing optical characteristics of exposed undeveloped photoresist, without removing the wafers from the stepper is disclosed. The present invention includes the steps of loading a wafer having a layer of photoresist into a photolithography system, exposing the photoresist in accordance with an initial set of control parameters including exposure time, position of the wafer within the photolithography system, and/or focus change. Prior to developing the photoresist, optical characteristics of the exposed photoresist are observed using a phase contrast microscope which detects latent images. Then, according to the observations of the latent image, the initial set of control parameters are adjusted to generate a second set of control parameters.Other References
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