Characterization of Bandgap Engineering on Operative Transistor Devices by Spectral Photon Emission

Photon emission as a characterization tool for bipolar parasitics in FinFET technology

“…The PEM measurements on p-channel FinFETs bore analogous results: PEM spectra on a parasitic pnp BJT (Fig. 9) show typical band-to-band recombination emission in silicon for the saturation mode and exponential decline overlaid by a band-to-band rekombination peak at 0.88V in active mode, indicating the presence of a Si0.75 Ge0.25 mixture [9]. Measurements on operating p-type FinFETs with gradually decreasing back-bias voltage show, that same as for the n-channel FinFET, a potential difference between source and body of more than 1V was necessary to activate the parasitic bipolar elements, see Fig.…”

“…The PE spectrum for this setup shows an overlay of two different effects: an exponential decline of a Boltzmann distribution originating from the relaxation of mobile charge carriers (analogous fig. 4) and a peak at ~0.9eV, indicating that the band to band recombination in the source/body region involved a silicon-germanium mix [9]. In order to assess the effects of bipolar parasitics on operating FinFET devices, we measured PE spectra of active FinFETs whilst gradually increasing the back-bias voltage.…”