Identification and control of edge leakage in mesa-isolated SIMOX MOSFETs

Summary form only given. Separation by implantation of oxygen (SIMOX) into silicon to obtain silicon-on-insulator substrates has emerged as the leading technology for radiation-hard integrated circuits. A key issue in building CMOS devices on SIMOX substrates is the device leaking current, which in turn determines the standby current of circuits. One cause of high leakage current is metal impurities incorporated during the oxygen implant. A second mechanism for leakage current in mesa-isolated SIMOX transistors is identified here. This current, which occurs along mesa edges, is more detrimental to circuit performance. It is random, and the probability of its occurrence increases with an increase in the number of edges, shorter-channel transistors, and/or longer source-drain anneal cycles. Measurements suggest that the random edge leakage is caused by enhanced lateral diffusion of source-drain dopants along the mesa edges.<
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