Effects of oxygen content, backside damage and polysilicon backsealed substrate on switching transistors and diodes

The effects of oxygen content, heavy arsenic doped n⁺ substrates of n/n⁺ epi wafers, on leakage of switching npn transistors and diodes were investigated. After device processing, the results indicated that too low an oxygen content resulted in surface defects due to insufficient gettering ability and too high an oxygen content resulted in a higher tendency for slip. Both surface defects and slip increase leakage current. The suitable range of oxygen for the transistors is different from that of the diodes. In the subsequent experiments, different levels of oxygen wafers with standard, quartz damaged and polysilicon backside conditions were tested. The results of these experiments indicated different optimum ranges of oxygen content for different backside conditions