Effect of Hole-Trap Distribution on the Power-Law Time Exponent of NBTI

• Published in: IEEE electron device letters Vol. 30; no. 7; pp. 751 - 753
• Main Authors: Ang, D.S., Lai, S.C.S., Du, G.A., Teo, Z.Q., Ho, T.J.J., Hu, Y.Z.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.07.2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Annealing; Applied sciences; Bias-temperature instability (BTI); Current measurement; deep-level hole traps (DLHTs); Devices; Electronics; Energy distribution; energy distribution of trapped holes; Energy states; Exact sciences and technology; Exponents; Gates; Hole traps; Hydrogen; Interface states; MOSFET circuits; Niobium base alloys; Niobium compounds; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Silicon; Testing; Titanium compounds; Transistors; Thermal stress; Negative bias temperature instability; Interface state; MOSFET; Annealing; Electric stress; Energy distribution; deep-level hole traps (DLHTs); Charge carrier trapping; Bias-temperature instability (BTI); interface states; Stress effects; Reliability; Conduction band; Power law; Hole traps; energy distribution of trapped holes; Damaging; Deep level
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/LED.2009.2020445

This letter presents a phenomenological relationship between the energy distribution of stress-induced hole traps and the power-law time exponent of NBTI. Experimental results show that increased generation of deep-level hole traps (DLHTs), i.e., trap-energy levels are near and/or above the Si conduction-band edge, yields a small exponent (< 0.2). Annealing the DLHTs results in the exponent increasing to ~ 0.3. Measurement on the n-MOSFET (in which the effect of DLHTs is suppressed) shows an exponent of ~0.4-0.5 for interface-state generation. This implies that the relatively small exponent (~0.3) of the p-MOSFET is due to remnant DLHTs which charge-up positively again when subjected to negative gate biasing during measurement. This new insight calls for a reexamination of the notion that as-measured exponents of ~0.14-0.17 are experimental proof of H 2 -diffusion-driven interface-state generation.