Development and Packaging of Microsystems Using Foundry Services

Micro-electro-mechanical systems (MEMS) are a new and rapidly growing field of research. Several advances to the MEMS state of the art were achieved through design and characterization of novel devices. Empirical and theoretical model of polysilicon thermal actuators were developed to understand their behavior. The most extensive investigation of the Multi-User MEMS Processes (MUMPs) polysilicon resistivity was also performed. The first published value for the thermal coefficient of resistivity (TCR) of the MUMPs Poly 1 layer was determined as 1.25 x 10(exp -3)/K. The sheet resistance of the MUMPs polysilicon layers was found to be dependent on linewidth due to presence or absence of lateral phosphorus diffusion. The functional integration of MEMS with CMOS was demonstrated through the design of automated positioning and assembly systems, and a new power averaging scheme was devised. Packaging of MEMS using foundry multichip modules (MCMs) was shown to be a feasible approach to physical integration of MEMS with microelectronics. MEMS test die were packaged using Micro Module Systems MCM-D and General Electric High Density Intercounect and Chip-on-Flex MCM foundries. Xenon difluoride (XeF2) was found to be an excellent post-packaging etchant for bulk micromachined MEMS. For surface micromachining, hydrofluoric acid (HF) can be used