High-etch rate processes for performing deep, highly anisotropic etches in silicon carbide using inductively coupled plasma etching

Abstract

This paper reports research performed on developing high rate of etch processes for the plasma etching of deep, highly anisotropic features into single-crystal 4H silicon carbide (SiC) substrates using an inductively coupled plasma process. To develop these etch processes, the authors conducted a design of experiments (DOE) whereby the most impactful etch process parameters were varied over predetermined values while the other etch process parameters were left unaffected. After performing an experimental etch on each sample, the samples were examined using various metrology methods to measure the etch outcomes. Using the investigational data accumulated during the DOE, the authors performed multiple regression analysis on this collected data in order to develop a model of the etch process that allows obtainment of desired outcomes, including a high etch rate, high mask selectivity, vertical sidewalls and minimal etch defects. Using optimized processes from the model, the authors were able to exhibit the ability to etch very deep features into SiC of more than 100 μm with nearly vertical sidewalls at high etch-rates. The capability to etch deep features at high etch rates into SiC is potentially useful for a number of microfabrication application areas.