SU-8微小网孔阵列结构的形貌优化工艺研究

Study on profile optimization process for micro mesh array structure by SU-8 photoresist

研究了曝光剂量对于小孔成型孔径的影响。实验中发现由于SU-8为负性光刻胶,曝光聚焦条件控制不佳会导致倾角较大的倒梯形结构,不利于液体喷射。为了实现陡直的图形结构,深入研究了衬底和紫外曝光焦平面的相对位置(散焦量),对于SU-8光刻胶图形边界倾角的影响机制。研究发现,当散焦量从-0.6μm变化到0.2μm时,SU-8光刻胶的图形边界的倾角从82.3°上升到90°再下降到88.4°,采用最优的90°图形倾角SU-8光刻条件应用于微小网孔的制作中,可以得到微网孔最优化倾角为89°,有利于液体从网孔中出射。应用SU-8光刻工艺,最终可实现最小孔径约3μm,总厚度约20μm,分布周期为300 dpi,均匀分布,一致性好的微小网孔片样品。该研究将有利于超小液滴雾化网孔片在电子烟及医学领域的应用。

Exposure dose dependent orifice diameter is studied.It is found that due to the negative photoresist of SU-8,poor control of exposure focusing conditions will lead to the inverted trapezoid structure with large inclination angle,which is not suitable for liquid ejection.In order to realize steep structure,the influence of the relative position between substrate and UV exposure focus plane,the defocusing amount,on the inclination degrees of SU-8 patterns are studied.It is found that when the defocusing amount changes from-0.6μm to 0.2μm,the dip angle of SU-8 photoresist pattern boundary changed from 82.3°to 90°,then decreased to 88.4°.The optimal lithography condition for the boundary pattern of 90°is applied to the fabrication of micro meshes,and the optimal angle of the micro mesh is 89°which is big improved for the liquid ejection.By using SU-8 lithography technology,micro mesh chip samples with the minimum diameter of 3μm,a total thickness of about 20μm and an uniform distribution period of 300 dpi are demonstrated.This study will be beneficial for the ultra-small droplet mesh atomizer being applied in the field of electronic cigarette and medicine.