Experiments on the Release of CMOS-Micromachined Metal Layers

Abstract

We present experimental results on the release of MEMS devices manufactured using the standard CMOS interconnection metal layers as structural elements and the insulating silicon dioxide as sacrificial layers. Experiments compare the release results of four different etching agents in a CMOS technology (hydrofluoric acid, ammonium fluoride, a mixture of acetic acid and ammonium fluoride, and hydrogen fluoride), describe various phenomena found during the etching process, and show the release results of multilayer structures.

Optimization of parameters for CMOS MEMS resonant pressure sensors

“…The suggested methodology for optimization and design can, in general, be used for any technology. However, in our case, it is currently being manufactured using CMOS MEMS technology where we perform release with dry hydrogen fluoride (HF) to etch out the oxide and release the back-end of line (BEOL) metal layer [11].…”

Characterization of CMOS-MEMS Resonant Pressure Sensors

“…The device release has been performed at the dice level in the UPC-DEE cleanroom with a hydrogen fluoride based etchant to release the back-end of line (BEOL) metal layers. The release was followed by resist removal and a rinse in methanol to reduce stiction issues and then the samples were dried in the oven [15], [16]. The reported capacitive pressure sensor, fabricated using IHP SG25 process, is implemented as a two aluminum layers (with a thickness of 2 µm and 3 µm) separated by a 3 µm thick tungsten via.…”

A Review on Key Issues and Challenges in Devices Level MEMS Testing

“…Electrostatic actuators typically have single cantilever, bridge, or two sets of comb fingers; the actuator is derived due to the change in polarity of the electric fields at the opposite fingers. Releasing of multistructure MEMS devices [115] is also a challenging job; occurrence of structural defects in comb fingers was found as one of the origins of failure. Rapid identification of failure mechanism of microstructures is essential.…”