ELECTRICAL STUDIES ON ANNEALED D2 PLASMA-EXPOSED SILICON

Defects introduced by annealing in D2 plasma-exposed, boron-doped silicon have been studied by means of deep level transient spectroscopy (DLTS) and capacitance-voltage measurements. A hole trap at E(v) = 0.48 eV (E(v) being the edge of the valence band) seen after annealing at 175-degrees-C, is tentatively assigned to a defect containing a vacancy. This hole trap anneals out following heat-treatment at 225-degrees-C. Other hole traps at E(v) + 0.30 eV and E(v) + 0.50 eV are observed in the samples following annealing at temperatures higher than 475-degrees-C. In the annealing temperature range 325-425-degrees-C, an observed broad DLTS band is attributed to complex defect structures in which deuterium atoms are bonded to an as-yet unidentified defect core. These structures are suggested to differ in the number of deuterium atoms bonded to the core. Each of these structures gives rise to a hole trap(s) in the energy range E(v) + 0.4 eV to E(v) + 0.6 eV within the forbidden gap. A nonzero residual DLTS signal seen in all the samples annealed at 525-degrees-C or below is proposed to be due to extended defects or platelets, confined to the first few microns region close to the plasma-exposed surface.