Methods and apparatus for improving microloading while etching a

Abstract

A method for improving microloading of a substrate to be etched in a plasma processing chamber. The substrate is etched with a first etchant to form trenches having a given trench width. The plasma processing chamber has a first power supply configured to energize a first electrode of the chamber and a second power supply configured to energize a second electrode of the chamber. The method includes obtaining a first data set among a plurality of data sets correlating power ratios of the first power supply and the second power supply with microloading percentages for the first etchant for different trench widths. The first data set correlates the power ratios with the microloading percentages for a first trench width. The first trench width approximates the given trench width as closely as possible. The method also includes extrapolating a second data set from the first data set. The second data set correlates the power ratios with the microloading percentages for the given trench width. There is also included ascertaining a power ratio of the power ratios of the second data set that yields a desired level of microloading. Additionally, there is included setting a first setting of one of the first power supply and the second power supply in accordance with the power ratio to achieve the desired level of microloading.