Fabrication of SiCN MEMS structures using microforged molds

Abstract

Ceramics and polymers are becoming attractive candidate materials for MEMS applications because of the wide range of properties that can be obtained and the promise of improved performance as compared to the existing materials set for MEMS. A challenge in the fabrication of ceramic MEMS is prohibiting cracking that can occur during processing. For example, this is significant in the development of a microcasting fabrication technique from a polymer precursor for silicon carbonitride (SiCN) MEMS. In this case, shrinkage mismatch between the SiCN structure and the microfabricated mold during thermal processes leads to significant stresses that can crack the ceramic structure. Here we propose an approach to overcome this problem that relies on demolding prior to the large shrinkage mismatch thermal processes, which itself is a nontrivial challenge. To this end, we propose a microforging process that facilitates demolding. We describe the process and show representative results for numerous SiCN ceramic microstructures.