FinFET刻蚀中刻蚀选择比及离子损伤的控制与优化

Control and Optimization of Etching Selectivity Ratio and Ion Damage in FinFET Plasma Etching

由于常规电感耦合等离子体刻蚀系统所产生的离子能量分布(IED)为离散的双峰且分布较宽,很难满足在鳍型场效应晶体管(FinFET)刻蚀中对高刻蚀选择比及低离子损伤的要求。利用减速场能量分析仪对比了13和60 MHz偏置射频频率对离子能量分布的影响,在偏置射频频率为60 MHz的条件下得到较为收敛的离子能量分布。进一步分析了13和60 MHz偏置射频频率条件下FinFET器件制造中底部抗反射层工艺的刻蚀选择比、Ar等离子体对氧化硅晶圆的刻蚀速率及刻蚀后鳍(Fin)表面氮化钛的剩余厚度。结果显示,当偏置射频频率由13 MHz提高为60 MHz时,获得了对氧化硅材料121.9的刻蚀选择比,且对氮化钛薄膜的刻蚀离子损伤降低了58.6%。

As the ion energy distribution(IED)generated by the conventional inductively coupled plasma etching system is bimodal and widely spread,it is difficult to meet the requirements of high etching selectivity ratio and low ion damage in FinFET etching process.The retarding field energy analyzer was used to compare the effects of 13 and 60 MHz bias RF frequency on IED,and a relatively convergent IED was obtained under the condition of 60 MHz bias RF frequency.The etching selectivity ratio of the bottom anti-reflective coating process,SiO2 etching rate in Ar plasma and the remaining thickness of TiN on the surface of Fin after etching were analyzed under the condition of 13 and 60 MHz bias RF frequency.The results show that when the bias RF frequency increases from 13 to 60 MHz,an etching selectivity ratio to SiO2 of 121.9 is obtained,and the etching ion damage for TiN thin film is reduced by 58.6%.