Development of new atomic scale defect identification schemes in micro / nanoelectronics incorporating digital signal processing methods for investigating zero/low field spin dependent transport and passage effects in electrically detected magnetic resonance.

摘要

This work focuses on the development of new techniques for the study of spin dependent transport and trapping centers in fully processed micro and nanoelectronics. The first, and most interesting, technique offers a very low cost means to study spin dependent transport in microelectronics as an alternative to electrically detected magnetic resonance (EDMR). EDMR measurements generally require strong static magnetic fields, typically 3 kG or greater, and high frequency oscillating electromagnetic fields, typically 9 GHz or higher. In this work, it is demonstrated that large spin dependent recombination and tunneling signals can be detected in the absence of the oscillating electromagnetic field at zero magnetic field. The physics behind this technique is based upon the mixing of singlet and triplet energy states of the electron spin pairs involved in the spin dependent processes. In this study, we show that this technique can be applied to Si and SiC based devices. Theoretically, it can be applicable to devices of all material systems in which defects play a role in spin dependent transport, some of which include CdTe and GaN. Although the resolution of the g value is sacrificed in this new measurement, the technique can detect electron-nuclear hyperfine interactions and possibly dipolar and exchange interactions. The technique also has great promise in microelectronic device reliability studies as it is directly applicable to time dependent dielectric breakdown in thin film dielectrics and bias temperature instabilities in transistors. Other applications of this new physics include self-calibrating magnetometers, spin based memories, quantum computation, and miniature EDMR spectrometers for wafer probing stations. The second technique involves the utilization of passage effects that arise when performing magnetic field modulation in EDMR. When certain conditions are met, the higher order harmonics of the spin dependent signal can contain much useful information; one of them being the fast passage signal. In this work, we designed a multiband virtual lock-in amplifier that can simultaneously demodulate any of these higher order harmonics. This tool has allowed for the identification of a very important recombination center in 4H SiC MOSFETs; the silicon vacancy. To the best of our knowledge, this was the first study that utilized passage effects for defect identification in EDMR. And finally, this work involves the development of an adaptive signal averaging technique that is capable of reducing the noise variance of a single scan by a factor of 10 or more which reduces the time of acquisition by the same amount. This technique is applicable to all methods in which signal averaging is utilized, some of which include medical imaging, electrocardiography, or electroencephalography.