Pre-Litho Back-Side Etch for Improved Flatness and Yield

It is well known in the semiconductor fabrication industry that pre-lithography backside defects can cause flatness issues. While traditional pre-photo cleans utilize a brush for backside particle cleaning, certain defects require more aggressive cleaning. This paper evaluated the addition of a backside etching process to reduce backside defects and the resulting impact on wafer flatness and yield.