Modeling of surface evolution in plasma etching for SiC microgroove fabrication

Abstract

Monocrystalline silicon carbide (SiC) has attracted attention for applications in devices operating in harsh environments due to its excellent physicochemical properties. However, it is difficult to obtain extremely small-feature sizes with undamaged surfaces due to its extremely high hardness. Herein, a novel method to fabricate SiC microgrooves is proposed that combines molding with inductively coupled plasma (ICP) etching process. First, a Ni–P microgroove master mold was fabricated by ultraprecision cutting and replicated on a polydimethylsiloxane (PDMS) surface, which was then used as the microgroove mold for hot embossing. Then, the patterned mask fabricated by hot embossing was transferred to the SiC substrate by ICP etching. To obtain customized microgrooves, an interface-evolution model based on angular dependence theory was established. A numerical method based on a string algorithm approach is developed for interface-evolution simulations. During ICP etching, the characteristic size d of homogeneous materials and the sidewall angle in heterogeneous materials varied with the sidewall angle of the SU-8 mask due to the angular dependence of etch rate. Finally, seven sets of microgrooves were machined on SU-8 to study the interface-evolution process. Variations in the characteristic size Δd and sidewall angle θ for each unit in homogeneous material, as well as the variations in sidewall angle before and after etching in heterogeneous materials are described. The high accuracy of the proposed interface-evolution model was experimentally validated.