120 V超快软恢复二极管用大尺寸硅外延材料工艺研究

Process Study of Large Scale Silicon Epitaxial Material Used for 120 V Super Fast Soft Recovery Diode

硅外延材料具有厚度和电阻率能精确调控、结晶完整性良好的优势,能够有效降低功耗,改善击穿电压,广泛应用于半导体分立器件。外延层厚度、电阻率、均匀性、晶格质量等参数指标直接决定了所制分立器件的良率和性能。通过研究平板式外延炉的热场和流场分布对材料均匀性的调制规律,在150 mm的大尺寸硅单晶衬底上化学气相沉积了高均匀性的硅外延材料。利用原子力显微镜(AFM)、傅里叶变换红外光谱仪(FTIR)、汞探针电容-电压测试仪(Hg-CV)等测试设备分别研究了外延材料的表面形貌、平整度、微粗糙度、厚度、电阻率、均匀性等参数。最终制备的外延材料的厚度和电阻率片内标准偏差均小于2%,而且表面无雾、滑移线等缺陷。制备的高均匀性的外延材料在应用于耐压为120 V的超快软恢复二极管后,解决了边缘电压低击穿现象,显著提升了器件的产出良率。

Silicon epitaxial material with thickness and resistivity can be accurately regulated,and with good crystal quality,could be applied to a variety of semiconductor discrete devices,reducing power consumption and improving the breakdown voltage.Silicon epitaxial material’s thickness,resistivity,uniformity,crystal lattice quality had directly determined the yield and performance of the device.In this work,we carefully studied a type of planar type epitaxial furnace’s thermal field and flow field distribution with the modulation rule of material uniformity,successfully preparing the 150 mm silicon epitaxial material with high uniformity on the large-scale silicon substrate by chemical vapor deposition method.Herein,the epitaxial material surface morphology,microroughness,resistivity,thickness,uniformity was analyzed by atomic force microscope(AFM),Fourier transform infrared spectrometer(FTIR),and mercury probe capacitance-voltage semiconductor measurement system(Hg-CV),respectively.Finally,epitaxial material’s thickness and resistivity’s standard deviation<2%,and the material surface cannot has haze and slip defect.The high uniformity of epitaxial material has been used for super fast soft recovery diode(SFSRD)which working voltage is 120 V,solving the low breakdown voltage phenomenon located at the edge of the material,significantly enhancing the device’s yield.