A batch-mode assembly and packaging technology for 3-axis tri-fold inertial measurement units
This paper reports a batch-mode generic 3-D precision assembly and wafer-level packaging technology for 3-axis tri-fold inertial measurement units (IMUs) using silicon mounting jig wafers with embedded vacuum channels. This approach allows use of optimized single-axis IMUs without manufacturing and structural constraints of forming 3-axis in a chip, and improving the overall yield by testing the chips prior to 3-D assembly. The 3-D chip assembly is performed by a controlled sequence of vacuum through the channels and bottom access holes, ambient pressurization, and raise of temperature to form permanent rigid tri-fold bond to the jig wafer.
Fabrication of multi-layer vertically stacked fused silica microsystems
In this paper, we present a fabrication process for an extremely compact, multi-layer, vertically-stacked fused silica microsystem. The system contains six fused silica layers in a total volume of less than 13 mm3. In the package are seven capacitive sensors designed as a six-degree of freedom inertial measurement unit plus a resonant timing device. Sixty-eight vertical electrical feedthroughs run through all six layers. Three key technologies are introduced: the fabrication of electrostatic devices on fused silica, the creation of through wafer vias in multiple layers of fused silica and stack bonding for 3-D integration of fused silica devices. The presented fused silica technology can be used for extreme miniaturization and integration of many future MEMS microsystems.
Piezoelectrically transduced high-Q silica micro resonators
In this paper, we report on high-performance piezoelectric-on-silica micromechanical resonators for integrated timing applications. Fused silica is used as the resonator structural material for its excellent material properties, and thin film aluminum nitride is used as the piezoelectric transduction layer. A silica resonator is demonstrated with a high quality factor (QU~25,841), low motional impedance (Rm ~350 Ω), and good power handling capability. The measured f×Q product of this resonator is the highest amongst reported micromachined silica/fused quartz resonators.