Abstract
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° (almost vertical), large-angle bevels ranging from 40° to 80°, and small-angel bevels ranging from 7° to 17° were achieved separately using distinct gas mixtures at different ratios. We found that SF6 with additive O2 was effective for vertical etching, with a best etching rate of 3050 Å/min. As for the large-angle bevel structures, BCl3 + N2 gas mixtures show better characteristics, exhibiting a controllable and large etching angle range from 40° to 80° through the adjustment of the mixture ratio. Additionally, a Cl2 + O2 mixture at different ratios is applied to achieve a small-angel bevels ranging from 7° to 17°. A minimum bevel angel of approximately 7° was achieved under the specific volume of 2.4 sccm Cl2 and 3.6 sccm O2. 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.
Highlights
Silicon carbide (SiC) is a wide bandgap compound semiconductor with excellent thermal conductivity, high electric breakdown voltage, and high-temperature stability, making it a good material for high-power, high-frequency, or high-temperature electronic devices, such as Schottky diodes, field effect transistors (FETs), and high-efficiency light-emitting diodes[1,2,3,4,5]
Another experiment investigated the effects of different gas mixtures on the formation of various angles and bevel structures, ranging from as low as 7°, 40°–80°, and up to as high as 90°
Different gas chemistries were used to obtain a variety of bevel angles for silicon carbide (SiC) substrates, and their performance for inductively coupled plasma reactive ion etching (ICP-RIE) etching was investigated and analysed
Summary
Silicon carbide (SiC) is a wide bandgap compound semiconductor with excellent thermal conductivity, high electric breakdown voltage, and high-temperature stability, making it a good material for high-power, high-frequency, or high-temperature electronic devices, such as Schottky diodes, field effect transistors (FETs), and high-efficiency light-emitting diodes[1,2,3,4,5]. Among the various dry etching techniques hitherto applied, inductively coupled plasma reactive ion etching (ICP-RIE) is the most widely adopted technique featuring a damage-free, highly anisotropic and selective, with a high etching rate. It allows independent adjustment of the gas mixture and the flow rate[15,16,17,18]. Several SiC diodes, transistors, and switches with high breakdown voltages (greater than 10 kV) have been reported, using a mesa shape with junction termination extensions formed by a notably large-angle bevel structure for SiC etching, which contributes to improve the breakdown voltage by alleviating the electric field crowding at the device edges[22]. The effect of bevelled sidewalls is to increase the depletion width at the surface of the device, and improve the breakdown voltage of the APD
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