Effect of supplemental O implantation on the radiation-induced hole traps in SIMOX buried oxides

Abstract

We describe electrical and spectroscopic measurements of SIMOX subjected to supplemental oxygen implantation and standard 1OOO" C post implantation annealing. Point contact transistor measurements indicate that the supplement a l oxygen implantation creates a net increase in radiationinduced trapped charge, and, surprisingly, electron paramagnetic resonance studies show that the 0 vacancy concentration increases. The electron paramagnetic resonance results suggest that the radiation tolerance of the supplemental oxides is due to insufficiently annealed implantation damage. A higher post supplemental anneal temperature minimizes the radiation-induced trapped charge, but further studies are necessary to assess the total impact of the high temperature anneal. I. BACKGROUNDSilicon on Insulator (SOI), a layered structure consisting of an SiO, film buried between two layers of Si, is a promising technology for providing device isolation for several new applications such as high speed, low power CMOS and high voltage devices. In addition, the buried oxide minimizes radiation-induced problems such as single event upset and dose-rate induced latchup [ll. Also, by lowering the capacitance the device speed is increased and power consumption decreased [21. Separation by the Implantation of Oxygen (SIMOX), one technique for forming the buried oxide, produces an oxide layer startlingly similar to a device grade thermal oxide. However, some studies suggest that excess Si exists in the buried oxide [3], and it is believed that this is responsible for some device related problems. For this reason, attempts to improve the oxide quality have focused on the implantation of additional oxygen followed by a standard 1 hour 10oO" C implantation anneal after the SIMOX process. Such oxides are referred to as supplemental oxides.In the past, both electrical and spectroscopic studies have been employed to investigate the buried oxide formed by ion implantation. Analysis of transistor current-voltage measurements following pulsed irradiation show that, unlike standard thermal oxides, buried oxides exhibit a high density of trapped holes and shallow electron trapping [4]. Such charge densities have indirect influence on CMOS/SIMOX devices and direct influence on fully depleted devices. Capacitance-voltage measurements made as a function of low temperature x-ray irradiation also indicate that high temperature annealed buried oxides contain a higher density of hole traps and shallow electron traps than device grade thermal oxides [5].

Impact of supplemental implantation of oxygen on defect centers in the separation by implantation of oxygen structure

“…When compared with our results, it refers to the importance of the postsupplemental anneal temperature, as also suggested in Ref. 20. Figure 1 shows the E ␥ Ј generation sensitivity depth profiles for the BOX of sample S and S sup .…”