Method for controlling etching depth

摘要

A method for controlling an etching depth in a semiconductor fabricating process is provided. The method includes steps of providing a substrate having a first reflecting region and a second reflecting region, illuminating the first reflecting region and the second reflecting region with a coherence light having a wavelength lambd to generate an interference, performing a first etching on the second reflecting region to generate a height difference between the first reflecting region and the second reflecting region, wherein the interference intensity is changed with the first etching, and performing a second etching on the second reflecting region for a specific period of time to make the etching depth as the height difference when the interference intensity is changed to a relative extreme value.