TABLE OF CONTENTS Motivated by the need for manufacturing high quality building blocks for optical applications, we have developed some micro-optical components and the corresponding technological micro-fabrication processes, focusing our efforts on the fabrication of single crystalline silicon micro-structures.
Among the most popular MEMS technologies, polycrystalline silicon and single-crystalline silicon are the dominant structural materials. Although they have been widely used for optical applications, surface micro-machined polycrystalline silicon structures have shown a number of limitations, the most important being:
mechanical stress and stress gradient in the very thin structures (typically 1 micron) leads to relatively significant curvatures, which is undesirable in optics, in mirrors for instance;
surface micro-machining of large area structures requires the insertion of arrays of micro-holes for the release step, which also affects the optical characteristics.
The use of SCS allows one to alleviate the above-mentioned drawbacks. Furthermore, there are other advantages in using this material:
it has superior mechanical properties as compared to polycrystalline silicon;
it has better surface quality (low roughness) and hence, better optical performance;
the crystalline nature can be used for alignment purposes;
sensing deformations by means of piezoresistive strain gages can be easily implemented.
In this chapter, we first present two advanced micro-fabrication processes using SCS., providing at the same time illustrations of their applications. The first one allows the fabrication of three-dimensional (3D) micro-objects of nearly all shapes and was used to realize...
