Process design for reactive ion etching of silicones

Abstract

In this paper, reactive ion etch process of silicone materials, specifically polydimethylsiloxane (PDMS), was characterised using Plackett-Burman fractional factorial and Box-Behnken response surface designs. These design of experiment techniques allow for efficient analysis of input parameters and their effects on response parameters. The Plackett-Burman design was used in screening for critical factors in eight experiments. RF power, pressure and flow rate of sulphur hexafluoride were determined as critical parameters. Oxygen and nitrogen gas composition in plasma had little positive effect on etch rate. The three-critical parameter, three-level Box-Behnken design produced 15 experiments. Based on the data obtained, the effects of critical parameters on the etch rate and surface roughness were studied. Response surface plots along with a second order polynomial were derived using statistical analysis software yielding an approximated model with R² = 99.53%.