  The total dose radiation and annealing responses of the back transistor of
Silicon-On-Insulator (SOI) pMOSFETs have been studied by comparing with those
of the back transistor of SOI nMOSFETs fabricated on the same wafer. The
transistors were irradiated by 60Co {\gamma}-rays with various doses, and the
front transistors are biased in a Float-State and Off-State, respectively,
during irradiation. The total dose radiation responses of the back transistors
are characterized by their threshold voltage shifts. The results show that the
total dose radiation response of the back transistor of SOI pMOSFETs, similar
to that of SOI nMOSFETs, depends greatly on their bias conditions during
irradiation. However, with the Float-State bias, rather than the Off-State
bias, the back transistors of SOI pMOSFETs reveal a much higher sensitivity to
total dose radiation, which is contrary to those of SOI nMOSFETs. In addition,
it is also found that the total dose radiation effect of the back transistor of
SOI pMOSFETs irradiated with Off-State bias, as well as that of the SOI
nMOSFETs, exhibits an increasing trend as the channel length decreases. The
annealing response of the back transistors after irradiation at room
temperature without bias, characterized by their threshold voltage shifts,
indicates that there is a relatively complex annealing mechanism associated
with channel length and type, bias condition during irradiation. In particular,
for all the transistors irradiated with Off-State bias, their back transistors
show an abnormal annealing effect during early annealing. All the results have
been discussed and analyzed in detail by the aid of simulation.
