Reactive ion etching (CF4+02 plasma) induced deep levels in metal-oxide-semiconductor devices

A reduction in device dimensions requires more accurate etching procedures. Reactive ion etching (RIE) provides many of the needed improvements. The energetic ions and photons produced by the glow discharge plasma of RIE, individually or in combination, can create lattice damage thereby forming trapping centers for electrons and holes at the Si-SiO2interface, as well as in the bulk silicon. In this work the capacitance-voltage (C-V) measurement techniques and deep level transient spectroscopy (DLTS) were used to investigate the interface trapping sites and the bulk defect centers at or near to the Si-SiO2interface region, produced by the energetic ions and/or photons present in the reactive ion etching. An electron trap level, ascribed to a bulk defect, was detected using the DLTS technique. In this study two types of metal-oxide-semiconductor (MOS) test structures were used to investigate the origin of damage. It has been observed that a major source of RIE damage in MOS structures and to the underlying silicon substrate can be energetic photons.