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. 6 μm to 0. 2 μm

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 3 μm

a total thickness of about 20 μm 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.