Heterosystem-integrated carbon nanotube sensors for on-ASIC condition monitoring

Konferenz: MikroSystemTechnik Kongress 2021 - Kongress
08.11.2021 - 10.11.2021 in Stuttgart-Ludwigsburg, Deutschland

Tagungsband: MikroSystemTechnik Kongress 2021

Seiten: 4Sprache: EnglischTyp: PDF

Boettger, Simon; Pankenin, Eric (Technische Universität Chemnitz, Center for Microtechnologies, Chemnitz, Germany)
Dietz, Franz; Gromala, P. (Robert Bosch GmbH, Reutlingen, Germany)
Dahra, Nipun; Kaulfersch, Eberhard (Fraunhofer Institute for Electronic Nano Systems (ENAS), Chemnitz, Deutschland)
Hermann, Sascha (Technische Universität Chemnitz, Center for Microtechnologies, Chemnitz, Germany & Fraunhofer Institute for Electronic Nano Systems (ENAS), Chemnitz, Germany)

This work demonstrates modular integrability of CNT-based nanodevices on top of the BEOL interconnect stack of a conventional ASIC enabling additional condition monitoring features in the framework of advanced prognostic health monitoring concepts. We highlight in particular a Nanoelectromechanical system (NEMS) technology featuring suspended CNTs with controllable prestrain to ensure detectability of smallest strain variation along with changes in the packing environment. The NEMS is generated by a CMOS-compatible surface micromachining process flow making use of a relaxation of prestrained layer stacks after local removal of a sacrificial-layer. Corresponding critical dimensions and design are derived from FE-simulations. The impressed strain into the nanomaterial is confirmed by Raman spectroscopy. According to this analysis, the CNT specific G-band exhibits a clear blue shift of 6.2 cm-1 upon membrane release indicating on axially acting tensile strain between up to 0.8%. For the piezoresistive sensors this corresponds to a significant reduction of the strain detection limit to 30 MPa and gauge factor of up to 644, which is around 5 times higher than for conventional Si-based strain gauges.