相移掩模和离轴照明在ArF浸没式光刻中对工艺窗口的影响

Process Window Improvement due to OAI and PSM for ArF Immersion Lithography

研究了交替型相移掩模及离轴照明对65nm分辨率ArF浸没式光刻的影响.在3/4环形照明和3/4四极照明方式下,分别选用传统掩模和交替型相移掩模,研究65nm线宽的密集线条、半密集线条、孤立线条在较大的曝光系统参数范围内,对光刻工艺窗口的改善。并对在不同的照明方式、掩模结构下获得的工艺窗口进行了比较.结果表明:①在较大焦深(DOF)范围内,满足光刻性能要求可以有较大范围的曝光系统参数配置;②相对于传统照明和传统掩模,采用交替型相移掩模或者离轴照明,焦深均可提高1000～1500.

Process window improvement is presented due to off-axis illumination(OAI) and phase-shifting mask(PSM) for 193 nm immersion lithography at 65 nm node. The process window under 3/4 annular and 3/4 quasar illumination at 5 0 0 exposure latitude is explored by optical imaging simulation. Line/space pairs of line-to-space ratio 1∶1(dense pattern), 1∶2(semi-dense pattern), 1∶4(isolated pattern) on binary mask and alternate phase-shifting mask(AltPSM) are consi- dered. Moreover, comparison of process window defined by depth of focus at 5 0 0 exposure latitude is made under various mask and illumination modes. The result shows (1) there is a wide area of numerical aperture and partial coherence for the comparatively large process window; (2) compared with conventional illumination on binary mask, depth of focus(DOF) will increase 100 0 0 to 150 0 0, if alternate phase-shifting mask, annular or quasar illumination are applied.