压印光刻对准中阻蚀胶层的设计及优化

Design and Optimization of Resist Film in Imprint Lithography Alignment Process

针对高速旋涂造成标记区阻蚀胶薄膜覆盖不对称和压印曝光造成标记区薄膜聚合的问题,利用压印光刻压印曝光固化脱模的工艺原理,提出了用压印预处理标记表面薄膜来优化阻蚀胶层厚度和形貌的工艺方法.该方法采用下压力约束薄膜,使阻蚀胶在标记区的栅格间重新分布,从而削弱了覆盖膜的不对称性,获得了相应的薄膜厚度.采用旋涂厚度为1.1μm的覆盖膜对压印预处理工艺方法进行了试验,发现下压力大于0.48 MPa时,薄膜结构具有较好的对称性,下压力为1.12 MPa时,对准信号的对比度达到最大.试验结果表明,压印预处理对于压印光刻系统具有较好的工艺适应性,利用该方法优化标记区的阻蚀胶层不仅能够有效削弱覆盖膜不对称和压印曝光的影响,而且对准精度可满足100 nm压印光刻的要求.

Asymmetric resist profile induced by spin coating and polymerization of resist with anomalous profile in exposure process are main problems in imprint lithography alignment. A novel technique based on the principle of imprint lithography process is proposed to solve these problems, where the thickness and morphology of resist film are optimized with restrained force. The redistributed resist has a symmetric profile and the effect of reflection from the top resist surface is greatly weakened by controlling the thickness of film. A basic forcing process is developed to obtain symmetric resist structure and maximum signal contrast using the film with the thickness of 1.1μm. The results show that symmetric resist profile can be achieved as the pressure is larger than 0.48 MPa and maximum signal contrast occurs as the pressure is 1.12 MPa. The alignment error caused by asymmetric resist profile or polymerized resist film on the marks can be reduced obviously to meet the requirements of imprint lithography within 100 nm.