Fast and accurate method of lifetime estimation for HfSiON/SiO2 dielectric n-MOSFETs under positive bias temperature instability

• Autores: Giyoun Roh, Hyeokjin Kim, Cheolgyu Kim, Dongwoo Kim, Bongkoo Kang
• Localización: Microelectronics reliability, ISSN 0026-2714, Nº. 72, 2017, págs. 98-102
• Idioma: inglés
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• Resumen

  • Abstract This paper proposes a fast and accurate method to measure the constants a and n of the power law ∆ Vth = atn for HfSiON/SiO2 dielectric nMOSFETs under positive bias temperature instability (PBTI), where ∆ Vth is a shift of threshold voltage, and t is stress duration. The proposed method requires one nMOSFET only, uses a voltage ramp stress (VRS), measures ∆ Vth vs. t data during VRS, uses a regression method to fit the data for each VRS pulse to the power law to obtain a and n at each stress voltage Vg,str, then obtains five voltage-independent constants for the power law after fitting the curves of a and n vs. Vg,str to empirical models. The five voltage-independent constants agreed very well with those obtained using the constant voltage stress (CVS) method. After obtaining the voltage-independent constants, the lifetime tL at an operating voltage Vop was estimated using the power law. The estimated tL = 1.67 × 108 s was quite close to tL = 1.74 × 108 s estimated using CVS, and to tL = 1.72 × 108 s estimated by extrapolating the ΔVth vs. t curve measured at Vg,str = Vop = 1.2 V to ΔVth = 200 mV. The time required for measurement was 900 s, compared to 30,000 s for the CVS method. These experimental results show that the proposed VRS-regression method is very useful for screening nMOSFETs under PBTI.