Excimer laser machining for the fabrication of analogous microstructures

Excimer laser ablation is normally used for micromachining of binary structures, for instance holes or cuts. We investigated new machining techniques for the fabrication of three-dimensional (3D) structures with analogous topology by excimer laser ablation: (i) line scan with a contour mask which correlates with the desired topology and (ii) gray scale mask projection. The structuring methods make use of the dependence of the machined depth (i) on the locally applied pulse quantity or (ii) on the energy density. The details of the methods, the process parameters and the resultant structure properties are discussed. Examples for the structuring of cylindrical and spherical microlenses and microarrays with dimensions in the micron range are given.