RF characterization of metal T-Gate structure in fully-depleted SOICMOS technology

The metal T-gate structure in fully-depleted (FD) silicon-on-insulator (SOI) MOSFET's is investigated from the RF perspective. With the expected low gate resistance R-G, the metal T-gate FD-SOI MOSFET achieves a higher f(max) of 67 GHz as compared with 12.5 GHz in the silicided polysilicon gate counterpart. However, the metal T-gate FD-SOI MOSFET has a lower f(T) of 35 GHz as compared with 44 GHz for the self-aligned polysilicon gate. The extracted parameters reveal that the T-gate structure results in an extra 40% and 80% increase in the parasitic capacitances C-gs and C-gd respectively. The metal gate structure together with the source-drain structure have to be co-optimized to boost the RF performance of FD-SOI MOSFET. A simple guideline to optimize the structure is included.