不同退火氛围对TiN/HfO2/SiO2/Si结构电荷分布的影响

热退火技术是集成电路制造过程中用来改善材料性能的重要手段。系统分析了两种不同的退火条件(氨气氛围和氧气氛围)对TiN/HfO₂/SiO₂/Si结构中电荷分布的影响,给出了不同退火条件下SiO₂/Si和HfO₂/SiO₂界面的界面电荷密度、HfO₂的体电荷密度以及HfO₂/SiO₂界面的界面偶极子的数值。研究结果表明,在氨气和氧气氛围中退火会使HfO₂/SiO₂界面的界面电荷密度减小、界面偶极子增加,而SiO₂/Si界面的界面电荷密度几乎不受退火影响。最后研究了不同退火氛围对电容平带电压的影响,发现两种不同的退火条件都会导致TiN/HfO₂/SiO₂/Si电容结构平带电压的正向漂移,基于退火对其电荷分布的影响研究,此正向漂移主要来源于退火导致的HfO₂/SiO₂界面的界面偶极子的增加。

Effects of Different Annealing Atmosphere on Charge Distribution of TiN/HfO2/SiO2/Si Structure

Thermal annealing technology is an important method to improve material properties in the integrated circuit manufacturing process.The effects of two different annealing conditions(ammonia atmosphere and oxygen atmosphere)on the charge distribution of the TiN/HfO₂/SiO₂/Si structure were systematically analyzed.The interface charge densities of the SiO₂/Si and HfO₂/SiO₂ interfaces,the bulk charge density of HfO₂ and the value of the interface dipole at the HfO₂/SiO₂ interface were given under different annealing conditions.The research results show that the interface charge density of HfO₂/SiO₂ interface decreases and the interface dipole increases,while the interface charge density of SiO₂/Si interface is hardly affected by annealing in ammonia atmosphere and oxygen atmosphere.Finally,the effect of different annealing atmospheres on the flat-band voltage of the capacitor was studied.It is found that two different annealing conditions lead to the positive shift of the flat-band voltage of the TiN/HfO₂/SiO₂/Si capacitor structure.Based on the study of the effect of annealing on its charge distribution,the positive shift of the flat-band voltage is mainly due to the increase of interface dipoles at the HfO₂/SiO₂ interface caused by annealing.