Title :
Threshold Voltage Reduction and Mobility Improvement of LTPS-TFTs With NH3 Plasma Treatment
Author :
Ma, W.C.-Y. ; Sheng-Wei Yuan ; Tsung-Chieh Chan ; Chi-Yuan Huang
Author_Institution :
Dept. of Electr. Eng., Nat. Sun Yat-sen Univ., Kaohsiung, Taiwan
Abstract :
In this paper, NH3 plasma directly applied to the surface of poly-Si channel is studied for the development of high-performance low-temperature polycrystalline-silicon thinfilm transistors (LTPS-TFTs) with HfO2 high-κ gate dielectric. The reduction of threshold voltage from 1.52 to 0.62 V, the decrease of subthreshold swing from 227 to 151 mV/decade, and the enhancement of field effect mobility μFE from 31 to 65 cm2/V s are observed after NH3 plasma surface treatment. It can be attributed to the NH3 plasma surface treatment enabling defect passivation and plasma-induced interfacial layer (PIL) growth. To decouple the impacts of defect passivation and PIL growth, the device without PIL is also fabricated. This paper demonstrates the important impacts of NH3 plasma surface treatment on the improvement of electrical characteristics of LTPS-TFTs.
Keywords :
elemental semiconductors; hafnium compounds; nitrogen compounds; passivation; silicon; thin film transistors; HfO2; LTPS-TFT; NH3; defect passivation; field effect mobility; high-κ gate dielectric; low-temperature polycrystalline-silicon thin film transistors; plasma surface treatment; plasma treatment; plasma-induced interfacial layer growth; threshold voltage reduction; voltage 1.52 V to 0.62 V; Hafnium compounds; Logic gates; Passivation; Plasmas; Thin film transistors; Interfacial layer; NH₃; NH3; low-temperature polycrystalline-silicon thin-film transistors (LTPS-TFTs); plasma passivation;
Journal_Title :
Plasma Science, IEEE Transactions on
DOI :
10.1109/TPS.2014.2352459
