基于同步辐射光刻的三维微细加工方法

Development of 3-D Microfabrication Method by SR Lithography

同步辐射光刻的三维聚甲基丙烯酸甲酯(Polymethyl Methacrylate,PMMA)微结构制造对X射线光刻掩膜板的吸收体形状和PMMA所吸收的X射线能量分布有直接影响,即三维PMMA微结构形状取决于X射线光刻掩膜板的吸收体形状。如果不对X射线光刻掩膜板进行补偿,在被曝光的结构中可观察到结构侧面的变形。研究了引起这种结构侧面变形的各种原因并提出X射线剂量对刻蚀深度非线性曲线是最直接的原因。基于X射线光刻掩膜板图形形状和实际制造的三维PMMA微结构的误差,X射线光刻掩膜板从双直角三角形变为双半圆图形使得微注射针阵列的强度得到增强。为了量化实际制造的三维PMMA微结构的误差,给出了X射线吸收能量分布与微结构的结构形状数据。

PMMA（Polymethyl Methacrylate） microstructures fabricated by X-ray lithography with plane-pattern to crosssection transfers technique has a direct influent from the absorber on X-ray mask pattern. Due to the dependency between the absorbed X-ray energy distribution in PMMA and the shape of absorber on the X-ray mask, without the compensation for mask design, the deformed shapes of sloped side-wall on the exposed structures are observed. The factors causing the deformation are investitated. The effect of dose-depth nonlinear curve is the most possible cause of the problem. Based on the measurement of errors occurred between the 2-D shape of mask pattern and the resulting wall of fabricated 3-D structure, the strength of microneedle is improved by changing the mask pattern from a double right-triangular pattern to a double semi-circular pattern. Moreover, in order to clarify the practical error, we have developed a useful graphical data of the structural profiles versus absorbed X-ray energy.