Boron diffusion into 6H-SiC through graphite mask

Experimental results are reported of selective diffusion of boron in 6H-SiC . Photoluminescence spectroscopy scanning electron microscopy cathodolumine scence imaging, secondary-ion mass spectroscopy optical microscopy, and sta in-groove technique were used to characterize the selectively doped regions fabricated by diffusion from the vapor phase through a graphite mask. Loca l p-doped regions of dimensions down to similar to 20 mum in diameter were formed on an n-type substrate using the graphite mask. Maximum concentratio n of boron atoms at the surface, obtained by SIMS, varied from 3 x 10(19) c m(-3) to 6 x 10(19) cm(-3), depending upon the temperature of diffusion, wh ile the p-n junction depth measured by the stain-groove technique varied fr om 0.5 mum to 1.2 mum. Planar p-njunction diodes fabricated on the diffused regions exhibited good rectification characteristics with a breakdown volt age of about 1000 V.