DIFFUSION PROFILES OF BORON IMPLANTED INTO PLASMA-ETCHED SILICON SURFACES

The diffusion of low-dose boron implanted into plasma-etched silicon surfaces is studied. The thermally grown oxide film on the silicon surface was plasma-etched in a CHF3/CO2 plasma. The samples were successively implanted and activated with boron and arsenic to form n+-p-n junctions to obtain a range of surface doping profiles and junction depths. The chemical and electrically active dopant concentrations were measured using the Secondary Ion-Mass Spectrometry (SIMS) and the Spreading Resistance Profiling (SRP) techniques. The silicon surface damage was characterized using the Transmission Electron Microscopy (TEM) analysis. It was observed that the diffusion profiles of boron were significantly affected when implanted into plasma-etched silicon surfaces. The samples with oxide films etched in a wet chemical etchant provided the control for evaluating the effect of the plasma etching process. These results suggest that the damage created during the plasma etching process may have caused changes in the boron diffusion profiles.