Method and system for realtime cd microloading control

Abstract

A method and apparatus for processing a semiconductor wafer is provided for reducing CD microloading variation. OCD metrology is used to inspect a wafer to determine pre-etch CD microloading, by measuring the CD of dense and isolated photoresist lines. Other parameters can also be measured or otherwise determined, such as sidewall profile, photoresist layer thickness, underlying layer thickness, photoresist pattern density, open area, etc. The inspection results are fed forward to the etcher to determine process parameters, such as resist trim time and/or etch conditions, thereby achieving the desired post-etch CD microloading. In certain embodiments, the CD and profile measurements, trim, etch processing and post-etch cleaning are performed at a single module in a controlled environment. All of the transfer and processing steps performed by the module are performed in a clean environment, thereby increasing yield by avoiding exposing the wafer to the atmosphere and possible contamination between steps.