(180bi) Response Surface Analysis of the Effect of Drie Process Parameters On Micro/Nanopillar Arrays

Micropillars and nanopillars are a desirable geometry in such applications as sensors and solar cells, due to their light absorption and confinement properties.  Deep reactive ion etching (DRIE) in the form of the Bosch process provides a straightforward method for forming micropillars and nanopillars in silicon; unlike other methods of growing or etching nanopillars or nanowires, DRIE is strongly controllable, as the process parameters may be varied to provide the desired surface roughness and depth.

Experiments were conducted to determine the effects of varying etching time, passivation time, power delivered to the ICP coil, and power delivered to the substrate platen on 2mm by 2mm arrays of 2μm diameter micropillars.  A circumscribed central composite design was used to enable analysis by response surface methodology.  The responses studied include mean surface roughness, scalloping depth, and profile angle.  The latter is used to form an empirical model for DRIE based on the process parameters described, which will be utilized in our current work in silicon micropillar array solar cells.