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1 200 V快恢复二极管(FRD)器件用200 mm外延片由于直径较大、外延层较厚(约130μm)以及电阻率较高(约60Ω·cm),外延层滑移线、电阻率不均匀性和缓冲层过渡区不易控制。通过在水平板式炉上进行工艺优化实验,采用900℃恒温工艺,外延层滑移线总长由原来的约90 mm降低至约15 mm。采用氢气变流量赶气工艺,外延层电阻率不均匀性由原来的约5%提升至小于3%。缓冲层结构生长之前,预生长本征覆盖层(帽层)可以降低缓冲层的过渡区宽度,由10μm降低至5μm,改善了缓冲层的有效厚度,同时也可以降低缓冲层的电阻率不均匀性,由2.5%降低至1.1%。以上措施的实施,满足了1 200 V FRD器件的材料指标要求,外延片出货量大幅度增加,提升了产业化水平。
The 200 mm epitaxial wafer for a 200 V fast recovery diode (FRD) device has a large diameter, a thicker epitaxial layer (about 130 μm), and a higher resistivity (about 60 Ω · cm), an epitaxial layer slip line, and a non-uniform resistivity Sexual and buffer zone transition zone is not easy to control. Through the process optimization experiment on the horizontal plate furnace, the total length of the epitaxial layer slip line is reduced from about 90 mm to about 15 mm by the 900 ° C constant temperature process. Using hydrogen flow rate hysteresis process, the resistivity non-uniformity of the epitaxial layer increased from about 5% to less than 3%. Pre-growth of the intrinsic coating (cap layer) prior to the growth of the buffer layer structure reduces the transition zone width of the buffer layer from 10 μm to 5 μm, which improves the effective thickness of the buffer layer and also reduces the non-uniform resistivity of the buffer layer Sex, from 2.5% to 1.1%. The implementation of the above measures has met the material index requirements of 1 200 V FRD devices, and the output of epitaxial wafers has risen sharply, raising the industrialization level.