Characterization of the Microloading Effect in Deep Reactive Ion Etching of Silicon

Knowledge of the magnitude and characteristic length scales of chip-scale process variations due to varying substrate pattern density is essential if compensation measures, such as incorporation of dummy structures, are to be taken during mask layout. Effects of variations in local pattern density on a deep reactive ion etch (DRIE) process have been investigated, and a decrease of the etch rate with increasing local pattern density within a characteristic radius of approximately 4.5 mm has been found. Analytical and numerical calculations confirm the existence of a similar depletion radius under the experimental conditions used.