Patterned SiC Substrate And New Preparation Of Patterned Sapphire Substrate

In preparing the device, the effective patterned etching techniques can achieve more functionality devices. For example, the production of high voltage Schottky barrier diode requires mesa etching of the SiC substrate for electrical isolation; digging a groove on SiC substrate in the process for preparing MESFET can bury the gate. Compared with wet etching and dry etching process of patterned sapphire substrate, the study of patterned SiC substrate at domestic and foreign is still in the initial state. This paper does the following work about patterned SiC substrate.1. The optimized etching power is200W and50W and the thickness of Ni mask is1.2μm. Patterned SiC substrate with stripe structure was prepared using Ni metal mask by photolithography, electron beam evaporation and ICP etching technique. The width of the mesa of stripe structure is5μm. The distance between mesas is7μm. The etching depth is1.8μm. The etched sidewalls are relatively steep and there is Micro-groove morphology at the end of sidewalls. These were watched through the picture of SEM. Surface impurities reduce a lot after cleaning of HF acid. The impurities are SiO2according to the date of XRD.2. Both sides of SiC were etched with the optimized process conditions. The etched rate of SiC with Si surface is60nm/min and the etched rate of SiC with C surface is57.5nm/min. The etched rate of Si surface is faster than C surface because C atom content of SiC with C surface is higher than SiC with Si surface during the etching. Layer of C atom will stop etching.3. The patterned SiC substrate with whole structure was prepared with the optimized process conditions. The etching time was extended. The whole diameter is2.5μm. The distance between holes is0.5μm and the etching depth is4μm. The deeper of etched depth means the steeper of sidewall, the deeper of the micro-groove and more severe of sidewall injure by picture of SEM.4. The patterned SiO2mask was prepared on sapphire substrate with the optimized process conditions. The width is2.7μm. The distance between mesas is9.3μm and the height is1μm. Sidewall is steep, but the sidewalls injure and impurities are still existed. The next work needs further study.