Self-aligned Block Oxide Process for bFDSOI Devices

This paper presents a novel self-aligned fully depleted silicon-on-insulator field-effect transistor with block oxide (namely SA-bFDSOI) and we investigate its ultra-short channel and thermal characteristics for the first time. In the case of SA-bFDSOI, the misaligned problem caused by two different exposures via the mask in a bFDSOI can be totally overcome. Moreover, the recessed source/drain (S/D) regions are formed to enhanced drain saturation current. According to the results of ISE TCAD simulation, the SA-bFDSOI provides better behaviour than FDSOI, which is closely similar to that of the ultra-thin body (UTB) SOI. This is due to the block spacer by the side of the Si-body that functions as a blocking layer to suppress the charge sharing existing in the depletion zone under the poly-Si gate. On the other hand, the thicker S/D regions can effectively suffer more and more heat occurred in the drain end resulting in improved thermal stability. Thus, the SA-bFDSOI is designed not only to maintain desirable properties, but also ameliorate the problem of a misaligned Si-body to the poly-Si gate.