Improvement of current drivability in high‐scalable tunnel field‐effect transistors with CMOS compatible self‐aligned process

Abstract

Two strategies are introduced herein to improve current drivability of tunnel field-effect transistors (TFETs). First, gate-to-channel coupling is increased by ∼22% in terms of effective gate capacitance (C ox) with the help of hemi-cylindrical device architecture. A novel iterative corner rounding process was developed for highly reliable gate dielectric formation without field crowding at sharp corner. The second approach is change channel orientation. The 〈100〉 and 〈110〉 oriented-channel TFETs were fabricated on (100) silicon surface. Consequently, both planar and hemi-cylindrical structures show consistent results that 〈110〉 is far better than 〈100〉 for higher on-current (I on). With these two structural improvements, the 〈110〉 hemi-cylindrical TFET shows ∼30× higher I on than that of the control (i.e. 〈100〉 planar TFET). Development Program) and in part by the Brain Korea 21 Plus Project in 2015.

Analysis of Current Variation with Work Function Variation in L-Shaped Tunnel-Field Effect Transistor

“…The L-shaped TFET features a mesa-shaped structure and an intrinsic Si region located between the source and gate dielectric layer to obtain high band-to-band tunneling (BTBT) due to the larger tunneling area than the planar TFET. The L-shaped TFET has remarkable advantages for low-voltage operation due to its small subthreshold swing (S) of less than 60 mV/dec, low-level OFF-state current (I OFF ) and high complementary MOS (CMOS) compatibility [7][8][9][10]. Based on the characteristics, the electrical performance of the L-shaped TFET can be more improved dramatically by applying the high-κ/metal gate (HKMG) technology [11][12][13].…”