FABRICATION OF THREE-DIMENSIONAL SU-8 MICROSTRUCTURES FOR MEMS APPLICATIONS

ABSTRACT In this paper, a novel method to realize three-dimensional microstructures is presented. The presented technology is based on a direct write technique using a scanning laser system to pattern thick-film SU-8. This technique combines the best features of photolithography techniques in multi-layer processing with the versatility of existing 3D prototyping technologies. It enables laser pulsing spot-by-spot for both inplane and in-depth processing. The results presented here represent the first step towards the realization of categories of MEMS devices with mechanical, optical, and/or biological functionalities. INTRODUCTION Recently, the interest in three-dimensional (3D) microstructures with mechanical, electrical, optical, and biological functionalities has increased dramatically Photolithography-based microfabrication using alternating thin films of structural and sacrificial materials has emerged as a preferred approach to manufacturing microscale systems and in fact has become the preferred technique in the fabrication of MEMS. The major advantage for this technique is that numerous devices can be produced in parallel as easily and quickly as one device, yielding low production costs in high volumes. However, photolithographic batch-processing techniques have limitations that have hampered their wide-scale penetration of MEMS into the market. Production in small and medium volumes is not economically practical due to the high cost of generating masks. This disadvantage is even more obvious during fast prototype development which is characterized by frequent changes in mask design. Moreover, the delay associated with this incremental improvement in design leads to excessively long development time. Additionally, while this technique [6] leverages the mature technologies developed over many years in the semiconducto