The study of plasma treatment on HfAlO gate dielectrics

• Main Author: 蘇明紳
• Other Authors: 張國明
• Format: Others
• Language: en_US
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/pn38kk

碩士 === 國立交通大學 === 電機學院微電子奈米科技產業專班 === 96 === When the MOSFET gate insulator is scaled below 1.2 nm, SiO2 as the gate insulator will has some serious problems such as direct tunneling. The moore’s law will face difficult condition to continue constantly. Therefore, high dielectric constant material is desired to replace SiO2. The oxide of using Hafnium-based is a most promising material for future MOSFET gate oxide applications. But the interface of between Si and high dielectric constant material has many defects, we will use plasma nitridation to solve this problem. In this study, we used Al-Ti-HfAlO-Si MIS capacitor as our analysis device. First, we used MOCVD system to deposit HfAlO. After oxidation process, we had an additional post-deposition annealing and then plasma treatment with N2, NH3, or N2O plasma for different process durations. Finally, the samples are treated by post-nitridation annealing to repair the surface of after plasma treatment. The electrical characteristics of the film under different oxidation conditions were discussed by C-V and I-V curves. Moreover, the reliability of the films under different plasma treatment conditions were discussed by high temperature treatment, hysteresis effect, SILC ( Stress Induced Leakage Current ) profile, CVS ( Constant Voltage Stress ) test and increasing temperature measurement. Among these conditions, the sample treated by N2O plasma for 30 sec represents the second capacitance ( 25.1 % increasing ), lowest leakage current ( 2 order reduction ), and excellent reliability. Since the nitrogen atoms of N2O plasma treatment can repair the defects of the interface, the oxygen atoms can form additional interfacial oxide between the high-k/Si interface to suppress the leakage current. The capacitance and the leakage current of the high-k dielectric can be improved by the N2O plasma treatment before the plasma damage occurring. On the contrary, the N2 and NH3 plasma treatment of the suitable time are also good methods to improve the interface characteristics.