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深硅刻蚀工艺是制造沟槽肖特基器件的关键技术。Si深槽的深度影响肖特基反向击穿电压,深槽的垂直度影响多晶Si回填效果,侧壁平滑度及深槽底部长草现象对器件的耐压性能影响显著。采用SF6/O2常温刻蚀工艺刻蚀Si深槽。研究了工艺压力、线圈功率、SF6/O2比例以及下电极功率等参数对沟槽深度均匀性和垂直度的影响。得到了使Si深槽形貌为槽口宽度略大于槽底,侧壁光滑,且沟槽深度均匀性为2.3%左右的工艺条件。利用该刻蚀工艺可实现沟槽多晶Si无缝回填。该工艺条件成功应用于沟槽肖特基器件制作中,反向击穿电压达到58 V,反向电压通48 V,漏电流为11.2μA,良率达到97.55%。
Deep silicon etching process is the key technology for manufacturing trench Schottky devices. The depth of Si deep trench affects the Schottky reverse breakdown voltage. The verticality of deep trench affects the effect of polycrystalline Si backfilling. The sidewall smoothness and long grass at the bottom of deep trench have a significant impact on the device’s breakdown voltage. Using SF6 / O2 room temperature etching process Si deep groove. The effects of process pressure, coil power, SF6 / O2 ratio and lower electrode power on the depth uniformity and verticality of the trench were studied. The process conditions that make the Si deep groove morphology slightly wider than the groove bottom, the side wall is smooth, and the groove depth uniformity is about 2.3% are obtained. Utilizing this etching process, trench polycrystalline Si can be seamlessly filled back. The process conditions were successfully applied to trench Schottky device fabrication. The reverse breakdown voltage reached 58 V, reverse voltage was 48 V, leakage current was 11.2 μA, and the yield was 97.55%.