Contactless laser bending of silicon microstructures

Abstract

We are going to present a new technology for laser bending of silicon microstructures based upon a suggestion of and carried out in cooperation with Prof. Dr. J. Frühauf from the Technical University Chemnitz (see acknowledgement). We investigated the influence of various laser process parameters on the bending angle and its reproducibility. Bending of the silicon element as a result of the laser induced thermal stresses in the material occurs toward the incident laser beam. The bending angle depends on a lot of laser process and material parameters. In particular we found that the irra-diation regime is well suited to control the bending angle. First substantial FEM based calculations of laser induced temperature fields using a moving laser heat source show the temperature field propagation in the material and reveal some regions of complicated overheating. As a result of our experiments we show a variety of examples including mul-tiple and also continuous bendings. There are several essential advantages compared to conventional bending technologies with this new method: Laser bending is contactless without using additional tools or external forces. Because of the local laser treatment the heat flux to the neighbouring material is minimized. The laser beam can be applied through windows of glass that means to al-most hermetically sealed micro devices. So laser technology is suitable for machining of already finished microsystems. It opens up a wide field of applications in micro system technologies: clip-chip-mechanism or sliding chips for micro optical benches, the adjustment of optical mirrors or other components or the ability of continuous bending for electro-static drives and so on.