聚甲基丙烯酸甲酯材质硬X射线组合Kinoform透镜的制作

摘要

为提高硬X射线聚焦元件的聚焦性能,利用LIGA(Lithographie,Galvanoformung,Abformung)技术,制备了深度为60μm的聚甲基丙烯酸甲酯(PMMA)材质硬X射线组合Kinoform透镜(CKL),并获得了良好的面形.制备的CKL以宽度为几个微米的细窄线条为主要结构,包括曲面和直角面形,线条最窄宽度为2μm.为保证CKL良好的曲面及直角结构,样品制备分为三部分:过渡掩模板的制备,LIGA掩模板的制备,以及最终样品的硬X射线曝光制备.在LIGA掩模板制备过程中,采用制备有纳米柱阵列的硅衬底有效解决了光刻胶脱胶的问题.在最终样品制备过程中,选用分子量较高的PM M A片作衬底,提高了PM M A刚度,有效缓解了细窄线条的倒塌黏连问题,保证了CKL的良好面形.在北京同步辐射光源(BSRF)成像站测试了CKL透镜的性能,结果显示其对于8 keV的X射线,聚焦焦斑的半高全宽(FW H M)为440 nm.%To improve the focusing performance of hard X-ray focusing elements , a hard X-ray Compound Kinoform Lens (CKL) based on Polymethyl methacrylate (PMMA) with a depth of 60μm is fabricated by LIGA ( Lithographie ,Galvanoformung ,Abformung)technology ,and its excellent morphology is obtained .The main structure of CKL is a narrow pattern with a few micron widths , including the curve and the rectangular surfaces ,and the width of the narrowest pattern is only 2μm . The fabrication of the CKL is divided into three parts to ensure its excellent morphology :the transitional mask preparation ,LIGA mask preparation ,and hard X-ray exposure to get the finial samples .T he nanopillar arrays on silicon substrate are used to solve the falling-off problem of the photoresist during the LIGA mask preparation .Then the PMMA sample with a high molecular weight is selected as the substrate to improve the rigidity of the PM M A and to relieve the adhesion and collapse of the narrow pattern in the final sample preparation .The focusing performance of CKL is tested at X-ray microscope beam-line of Beijing Synchrotron Radiation Facility (BSRF ) . The experiment result for an 8 keV X-ray at transmission shows its full-width-at-half-maximum (FWHM ) peak size for focusing spot is 440 nm .