Dielectric Films as Crosspoints in Switching Matrices

摘要

A critical evaluation was made of conductor-thin insulator film-conductor structures as practical bi-stable switching elements. More than a dozen of the materials considered promising for this purpose were used to fabricate metal-thin dielectric film-p silicon (ohmic back contact) test devices. The only ones capable of repetitive switching and having a high off/on resistance ratio are silicon oxide, silicon nitride, aluminum oxide and silicon nitride-on-silicon oxide films. Under properly chosen conditions, the test device switched via 'selfhealing' breakdown, but since a current pulse was used to switch it off, Joule heating is unavoidable and a local erosion of the electrode does result. Therefore, the switching process is destructive, although the device may function for many cycles. The inference of electrode destruction, drawn from electrical and visual observation of devices under test, was supported by scanning electron microscopic examination of devices during self-heal breakdown, and by phase contrast microscopy, plus conductance and capacitance of the devices after SEM studies and after electrical evaluation. Experiments were performed to introduce impurities during device fabrication, with the hope that different modes of switching in these films would result. However, we failed to detect any significant changes. (Author)