Poly-Si Finlike Thin-Film Transistors With Various Wide Drain Designs for Radio Frequency and 3-D Integrated Circuits

The dc and high-frequency performance of p-type polycrystalline silicon (poly-Si) finlike thin-film transistors (FinTFTs) with various wide drain region designs are investigated herein. The poly-Si FinTFT with the triangular wide drain design exhibits a high I
_ON
/I
_OFF
current ratio (>10
⁷
) and high cutoff frequency (f
_T
=371.5 MHz at V
_DS
=-1 V). This structure has lower drain series resistance R
_d
than does the conventional poly-Si FinTFT and lower gate-to-drain capacitance C
_gd
than does the poly-Si FinTFT with the hybrid wide drain design. This result indicates the possible use of poly-Si TFT technology for radio frequency integrated circuits and the great potential for future use in 3-D integrated circuits.