Control of Si-Island Free Ultra-Thin Simox Structures by Implant Energy and Oxygen Dose

Abstract

To serve the needs of future submicron electronic applications such as cellular communications and character recognition, the computational elements have to be drastically reduced in size as well as power consumption. A promising approach is based on implantation of oxygen ions into a silicon substrate and subsequent high temperature annealing. The process when properly done, results in a very thin silicon layer separated from the bulk silicon substrate by a thin layer of silicon oxide. In these SIMOX elements the top silicon layer is seriously degraded by defects introduced by the ion implantation process, consequently affecting the performance of devices built on them. A careful selection of processing parameters such as implant energy and dose is essential in order to minimize the defect densities. It is believed that Si interstitials are the main reason for the formation of most defects in SIMOX [1]. Consequently, the reduction of the implant oxygen dose minimizes the Si interstitials, and finally lowers the defect densities in both the top Si and buried oxide layers.