Spectroscopic photon emission measurements of n-channel MOSFETs biased into snapback breakdown using a continuous-pulsing transmission line technique

Abstract

As device dimensions decrease without a proportional reduction in the supply voltage, short-channel MOSFETs may be operated at voltages close to drain-to-source breakdown. The single-pulse transmission line technique has been used previously to study devices under electrostatic discharge (ESD) as it allows the suppression of unwanted reflections. In this paper, a modified continuous-pulsing transmission line technique is combined with a spectroscopic photon emission microscope set-up to investigate photon emissions from short-channel MOSFETs biased into snapback and second breakdown. This new technique enables the photon emission spectra from a grounded-gate nMOSFET biased into snapback to be studied, with only minimal degradation to the device under test. Photon emission spectra of the grounded-gate nMOSFET biased into the snapback region showed that the spectra are a combination of the spectra for a forward-biased and reverse-biased p-n junction. A very weak emission at a wavelength of 375 nm (3.3 eV) was also detected, and this was suspected to be due to the injection of hot electrons into the gate oxide. By fitting the photon emission spectra obtained to the electron temperature model, the carrier temperature of an nMOSFET biased into snapback was also obtained.