Flexible fabrication of deep microstructures by laser-induced backside wet etching

Abstract

By laser-induced backside wet etching (LIBWE), we can fabricate deep microstructures with high aspect ratios. To fabricate such deep microstructures by means of a mask-projection system, appropriate optimization of the sample positions is indispensable to maintain the imaging conditions of the mask-projection system at the etch front. By applying the appropriate optimization, the trenches with homogeneous widths and high aspect ratios could be fabricated. At present, a trench with an aspect ratio of 102 (width: 9.7 μm, depth: 986 μm) was successfully prepared. When the irradiated area was gradually shifted in a direction perpendicular to the incidence of the laser beam, inclined features could be fabricated in the deep microtrenches. The tilting angles of the features could be can be flexibly controlled between -30° and +30° by changing the shifting speed. Moreover, the angles could be varied within a single deep microtrench. Fabrication of deep microhole array was also demonstrated. Fabricated microholes were converted into through holes on grinding.