光学 精密工程, 2017, 25 (11): 2803, 网络出版: 2018-01-17
大高宽比硬X射线波带片制作及聚焦测试
Fabrication and focusing test of hard X-ray zone plates with high aspect ratio
硬X射线波带片 电子束光刻 大高宽比波带片 电子束光刻 镂空薄膜 hard X-ray zone plates electron beam lithography high aspect-ratio zone plate electron beam lithography self-standing film
摘要
为得到同步辐射光源硬X射线波段(>2 keV)需要的高宽比高分辨率波带片,本文利用高加速电压(100 kV)电子束光刻配合Si3N4镂空薄膜直写来减少背散射的方法,对硬X射线波带片制作技术进行了蒙特卡洛模拟和电子束光刻实验。模拟结果显示: Si3N4镂空薄膜衬底可以有效降低电子在抗蚀剂中传播时的背散射,进而改善高密度大高宽比容易引起的结构倒塌和粘连问题。通过调整电子束的曝光剂量,在500 nm厚的镂空Si3N4薄膜衬底上制备出最外环宽度为150 nm、金吸收体的厚度为1.6 μm,高宽比大于10的硬X射线波带片。同时,引入随机支撑点结构,实现了波带片结构自支撑,提高了大高宽比波带片的稳定性。将利用该工艺制作的波带片在北京同步辐射装置X射线成像4W1A束线8 keV能量下进行了聚焦测试,得到清晰的聚焦结果。
Abstract
The high-resolution hard X-ray (>2 keV) Fresnel zone plates with high density and high aspect ratio was fabricated for Synchrotron Radiation Light Source. The electron beam lithography and the fabrication of hard X-ray zone plates were simulated with Monte Carlo method by combining high accelerating voltage (100 kV) with Si3N4 self-standing film to reduce the backscattering. The simulation result shows that Si3N4 self-standing film substrate effectively reduces backscattering when electrons propagate in the resist, so that the structure collapse and adhesion caused by high density and high aspect ratio are overcome. By adjusting the electron beam exposure dose, hard X-ray Fresnel zone plates with the outermost ring width of 150 nm, gold absorber thickness of 1.6 μm and the aspect ratio more than 10 were fabricated on a 500 nm Si3N4 self-standing film. Meanwhile, a random support structure was introduced to realize the self support of the zone plates and to improve their stability. The focusing properties of the zone plates fabricated were tested with energy of 8 keV at 4W1A beamline of Beijing Synchrotron Radiation Facility, and a clear focusing result was obtained.
李海亮, 史丽娜, 牛洁斌, 王冠亚, 谢常青. 大高宽比硬X射线波带片制作及聚焦测试[J]. 光学 精密工程, 2017, 25(11): 2803. LI Hai-liang, SHI Li-na, NIU Jie-bin, WANG Guan-ya, XIE Chang-qing. Fabrication and focusing test of hard X-ray zone plates with high aspect ratio[J]. Optics and Precision Engineering, 2017, 25(11): 2803.