Mechanical Properties Measurements of 0.35-μm BiCMOS MEMS Structures

摘要

CMOS-MEMS mechanical properties, such as effective Young's modulus, axial residual stress, and vertical and lateral stress gradients, are strongly dependent on composition, i.e., relative metal and dielectric content. Test structures, measurements and FEA simulations are reported on these four mechanical properties for high-aspect-ratio (HAR) MEMS structures with different compositions, formed by post-CMOS micromachining of two different 0.35-μm BiCMOS technologies provided by Jazz Semiconductor and STMicroelecronics. FEA simulation results verify the experimentally extracted values of effective Young's modulus and axial residual stress. Die-to-die effective Young's modulus variations are 2 GPa for Jazz chips and 3 GPa for ST chips. Variations of axial residual stress, and vertical and lateral stress gradients are strongly dependent on post-CMOS processing.