Micro Stereolithography Using A Liquid Crystal Display As Exposure Mask

The automotive industry is of key importance in all European countries, in the USA, and in Japan. In order to fulfill the technical and economic requirements of future cars, a consequent utilization of technological developments is necessary. Of paramount importance are miniaturization technologies for sensors, microelectronics and their integration into microsystems. At the moment, a micro fabrication technique for three dimensional structures with high resolution is demanded. Stereolithography allows to manufacture 3D objects made of polymers directly from CAD data. The basic principle is the solidification of a liquid resin which is sensitive to light. The technology tends to be limited to manufacture small objects (e.g., micromechanical parts). Nevertheless, it seems important to broaden this principle to manufacture elements directly usable in microtechnology. The micro stereolithography process described in this paper is mapping an exposure mask in reduced scale to the surface of the resin. A further advantage is the possibility to use a Liquid Crystal Display (LCD) as exposure mask. This reduces the mechanical effort very drastically since there are no more moved elements apart from the elevator. The radiation is generated by a rod-shaped lamp (e.g., a halogen lamp). The LCD is controlled by a micro computer and displays the cross section pattern of the layer which should be exposed. An objective maps this pattern to the surface of the resin. Several experiments have been performed in order to demonstrate that the micro stereolithography process is suitable to manufacture micromechanical parts.