Monolithic High-Aspect-Ratio Embedded Parylene Channel Technology: Fabrication, Integration, and Applications

This paper presents a novel channel fabrication technology of monolithic bulk-micromachined embedded channels. Based upon implementing two-step complementary dry etching technique and conformal parylene C layer deposition, high-aspect-ratio (internal channel height/internal channel width, greater than 20) polymer channels with uniform quasirectangular sidewalls have been successfully fabricated in one silicon wafer. The fabrication is completely compatible with further lithographic CMOS/MEMS process, which enables its total integration with on-chip micro sensors/actuators/structures for lab-on-a-chip applications. An exemplary process has been successfully demonstrated to verify the possibility of combining bulk micromachining and surface micromachining. This proposed formation of channels can be extensively used as beam elements in micromechanical devices or microcolumns for high-performance/high-throughput chip-based separation analysis. A spiral parylene column longer than 1.1 m embedded in a 3.3 mm x 3.3 mm chip has been presented as a prospective element in micro gas-chromatography (µGC)