45nm分辨率增强技术优化

Optimization of resolution enhancement technique at 45 nm node

针对45nm节点的需求,系统分析和研究了该节点不同周期图形的成像规律,并采用了不同的分辨率增强技术进行对比研究,从中分析出最适合45nm不同周期图形的光刻方案。采用了传统的离轴照明技术及新照明方式进行对比,并结合交替式相移掩模、衰减式相移掩模及传统二元掩模进行分析,探讨了45nm节点不同周期图形的可实现性。通过优化光源参数,采用Y偏振,对比不同分辨率增强技术的组合,得出结论,采用双弧带照明,对于Y向Line/Spcae图形,其焦深,对比度等参数均可满足45 nm节点需要。最后通过双底层抗反射层(DBARC)优化,减小了底层反射率,有效地降低了摇摆效应,提高了Z向图形保真度。

Different Resolution Enhancement Technologies （RET） were studied at 45 nm node. To meet the requirement of 45 nm node, patterns of different pitches were analyzed and compared for selecting the best choice for 45 nm node lithography. Traditional Off - Axis Illumination （OAI） and new illumination were used for comparison together with different mask types （alternating PSM, attenuating PSM and binary mask）. The printability of their combination using the immersion tools was considered. Also, for hyper NA imaging, polarization effect was taken into consideration for analysis. By optimizing the illumination and combined with PSM, the new OAI named double arc together with Y -polarization had obviously improvement for DOF. Finally, Double Bottom Anti Reflectivity Coating （DBARC） was used and their thicknesses were optimized, reduced the swing curve effect, and improved the image fidelity through the resist.