A Hybrid Wide Drain Poly-Si FinTFT for RF Application

In this paper, a hybrid wide drain polycrystalline silicon (poly-Si) fin-like thin-film transistor (FinTFT) for radio frequency (RF) applications is fabricated. A high I
_ON
/I
_OFF
current ratio (>10
⁸
) and favorable gate control (SS = 198 mV/dec) are observed, and a high cutoff frequency (f
_τ
= 9.55 GHz @ V
_DS
= 1 V and 12.45 GHz @ V
_DS
= 2 V) is achieved. The hybrid wide drain poly-Si FinTFT developed in this paper exhibits excellent gate controllability and good high-frequency characteristics as compared with the conventional poly-Si TFT. The effect of the extended length of wide drain on the high-frequency characteristics of poly-Si FinTFT is investigated and analyzed by using the extracted small-signal parameters. Increasing the extended length not only can improve the high-frequency performance which degrade due to additional fringing capacitance in 3-D multigate structure but also can increase the breakdown voltage. This result suggest the possible use of the poly-Si TFT technology for RF integrated circuits and show a great potential to the future system on panel or system on glass.