Nanocalorimetry for plasma metrology relevant to semiconductor fabrication

This letter reports on pilot tests of microfabricated nanocalorimeters as a metrology platform for rapid (<40 ms response time) and sensitive (in the range of 1020 m−2 s−1–1017 m−3 for radicals’ flux and density, respectively) detection of neutral radicals generated by reactive cold plasmas. The setup consists of a nanocalorimeter resistive sensor coated with a catalyst alongside an inert reference sensor with identical thermal masses. By measuring the temperature increase in the active sensor caused by radical surface recombination reactions and comparing it to the reference sensor, parasitic stimuli such as IR/visible/UV irradiation and ion- and/or electron-induced heat fluxes can effectively be isolated. The system was successfully tested in a hydrogen plasma environment, and critical performance metrics such as sensitivity and response time were evaluated and benchmarked against the existing plasma radical diagnostic techniques.