High voltage, high speed lateral IGBT in thin SOI for power IC

Summary form only given. A lateral IGBT (LIGBT) built in thin SOI with a breakdown voltage higher than 700 V is reported for the first time. SOI wafers have been considered superior to bulk substrates for power IC applications. There have been reports on using a linearly graded dopant profile in the drift regions of PIN diodes and LDMOS devices in ultra-thin (<0.2 μm) SOI substrates to achieve high breakdown voltages. Reports have also shown that LIGBTs built in thin SOI substrates have faster switching speed than bulk and thick SOI counterparts. In principle, by employing a linearly graded profile in the drift region of an LIGBT, one would expect a device with low forward drop, high breakdown voltage and fast switching speed, which is ideal for high voltage and high speed applications. However, the thickness of the SOI layer (T_si) in these devices is very crucial. Too thin a T_si will lead to problems such as high forward voltage drop, incapability in high-side configuration and high latchup susceptibility. If T_si is too large, however, an unrealistically thick buried oxide has to be used for high breakdown voltages and a linearly graded drift region will be difficult to achieve due to the two-dimensional diffusion of dopants