Vertical and bevel-structured SiC etching techniques incorporating different gas mixture plasmas for various microelectronic applications

This study presents a detailed fabrication method, together with validation, discussion, and analysis, for state-of-the-art silicon carbide (SiC) etching of vertical and bevelled structures by using inductively coupled plasma reactive ion etching (ICP-RIE) for microelectronic applications. Applying different gas mixtures, a maximum bevel angle of 87 degrees (almost vertical), large-angle bevels ranging from 40 degrees to 80 degrees, and small-angel bevels ranging from 7 degrees to 17 degrees were achieved separately using distinct gas mixtures at different ratios. We found that SF6 with additive O-2 was effective for vertical etching, with a best etching rate of 3050 angstrom/min. As for the large-angle bevel structures, BCl3 + N-2 gas mixtures show better characteristics, exhibiting a controllable and large etching angle range from 40 degrees to 80 degrees through the adjustment of the mixture ratio. Additionally, a Cl-2 + O-2 mixture at different ratios is applied to achieve a small-angel bevels ranging from 7 degrees to 17 degrees. A minimum bevel angel of approximately 7 degrees was achieved under the specific volume of 2.4 sccm Cl-2 and 3.6 sccm O-2. These results can be used to improve performance in various microelectronic applications including MMIC via holes, PIN diodes, Schottky diodes, JFETs' bevel mesa, and avalanche photodiode fabrication.