In-Situ N2-Plasma Nitridation for High-k HfN Gate Insulator Formed by Electron Cyclotron Resonance Plasma Sputtering

Shun-ichiro OHMI  Shin ISHIMATSU  Yuske HORIUCHI  Sohya KUDOH  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E103-C   No.6   pp.299-303
Publication Date: 2020/06/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.2019FUP0001
Type of Manuscript: Special Section PAPER (Special Section on Fundamentals and Applications of Advanced Semiconductor Devices)
Category: Semiconductor Materials and Devices
Keyword: 
high-k,  gate insulator,  interfacial layer,  nitridation,  N2-plasma,  ECR,  HfN,  

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Summary: 
We have investigated the in-situ N2-plasma nitridation for high-k HfN gate insulator formed by electron cyclotron resonance (ECR) plasma sputtering to improve the electrical characteristics. It was found that the increase of nitridation gas pressure for the deposited HfN1.1 gate insulator, such as 98 mPa, decreased both the hysteresis width in C-V characteristics and leakage current. Furthermore, the 2-step nitiridation process with the nitridation gas pressure of 26 mPa followed by the nitridation at 98 mPa realized the decrease of equivalent oxide thickness (EOT) to 0.9 nm with decreasing the hysteresis width and leakage current. The fabricated metal-insulator-semiconductor field-effect transistor (MISFET) with 2-step nitridation showed a steep subthreshold swing of 87 mV/dec.