Electric field affects the charge state in ion-implanted Si-SiO₂ structures

Abstract

Using the method of depth profiling based on the measurement of high-frequency voltage-capacitance characteristics in an electrolyte-insulator-semiconductor structure in combination with the insulator layer etching, it was found that Ar ion implantation into the oxide film of a Si-SiO₂ structure (oxide thickness, 250 nm) leads to the formation of positively charged (outer) and negatively charged (inner) layers in the SiO₂ film beginning with an implanted ion dose of 10¹⁴ cm⁻². The effect of an external electric field upon the charge state in these ion-implanted structures was studied. It was established that the negatively charged centers represent hole traps, which are recharged by the applied field to a neutral state. It is suggested that these centers are related to the appearance of nonbridging oxygen atoms as a result of the silicon oxide film reconstruction induced by the ion implantation to a dose exceeding 10¹⁴ cm⁻².