Impact of incomplete ionization on indium doped buried channel pMOSFETs

We have investigated the properties of indium for channel doping engineering, and have fabricated 0.2 mu m buried channel pMOSFETs with a shallow counter doping layer formed by indium and analyzed them using a simple model. It is difficult to lower the threshold voltage due to the significant amount of indium loss caused by the high diffusivity of indium in oxide and the segregation behavior at the silicon-oxide interface. If diffusion blocking implantation on gate polysilicon is used, the loss of indium due to diffusion through the thin gate oxide can be prevented. But it is still difficult to lower the threshold voltage due to room temperature freeze-out effect of indium.