基于纳米划痕的电子束光刻胶微观力学性能研究

目的 研究不同厚度的ZEP-520电子束光刻胶胶层的韧性以及其与衬底间的结合强度等力学性能,为解决光刻胶层在使用过程中的开裂及脱落问题提供实验支持.方法 利用纳米划痕技术对不同厚度下的ZEP-520电子束光刻胶进行了划痕测试,分析了光刻胶开始破损和完全脱粘时的临界载荷,研究了胶层厚度与光刻胶韧性的定量关系,并以光刻胶胶层与硅基底的结合能评价了其结合强度.此外,在厚度为587 nm的光刻胶胶层上,利用电子束曝光技术成功制备了频率为10000线/mm的高质量正交光栅,采用几何相位分析法对栅格间距误差进行了定量表征.结果 ZEP-520光刻胶胶层的韧性、结合力以及结合能均随胶层厚度的增加而增加,结合能在光刻胶胶层厚度大于529 nm时,趋于定值0.17 J/m2.利用几何相位分析法测得所制备的光栅间距误差在1.3％以内,并且未存在开裂以及脱粘等现象.结论 在ZEP-520电子束光刻胶胶层微纳米成形过程中,适当增加光刻胶胶层厚度可以有效增强胶层韧性和其与衬底之间的结合力,缓解光刻胶胶层在使用过程中出现裂纹与脱落的现象.

Study on Micromechanical Properties of Electron Bean Photoresist Based on Nano-scratch Technology

The purpose of this paper is to provide experimental support for the cracking and debonding of the photoresist layers in use through the study of toughness of ZEP-520 electron beam photoresist layer with different thickness and the bonding strength between the substrate. By using nano-scratch technology to test the ZEP-520 electron beam photoresist with different thicknesses and analyzing the critical load when the photoresist begins to break and completely debond, the quantitative relation between thickness of the adhesive layer and toughness of the photoresist is studied, and the bonding strength is evaluated with the bonding energy of the photoresist and silicon substrate. In addition, a high-quality orthogonal grating with a frequency of 10,000 lines/mm is successfully fabricated on a 587 nm thick photoresist layer with the electron beam exposure technology, and the geometric phase analysis method is used to quantitatively characterize the grating pitch error. The results show that the toughness, bonding force and bonding energy of the ZEP-520 photoresist layer increase with the thickness of the photoresist layer, and the bonding energy tends to a fixed value of 0.17 J/m2 when the thickness of the photoresist layer is greater than 529 nm. Finally, the measured prepared grating pitch error is within 1.3% by the geometric phase analysis method, without cracking and debonding phenomenon. It is proposed that increasing the thickness of the photoresist an appropriate during the micro/nano molding process of ZEP-520 photoresist can effectively enhance its toughness as well as adhesion to the substrate, and reduce the cracks and debonding of the photoresist during use.