Selective Laser Doping From Boron Silicate Glass

Laser-assisted diffusion of dopants is a promising way to produce selective doping structures such as selective emitters or localised BSF with a reduced number of technological steps. This paper discusses laser-induced selective diffusion of boron from two types of borosilicate glasses (BSG) produced either by low-pressure diffusion using a BCl3 gas source or deposited by PECVD from a trimethylborate (TMB) liquid source. Laser parameters were optimised for efficient heat-assisted diffusion of boron atoms with reduced damage to the silicon substrate. Sheet resistance variation of about 60 ohm/sq was measured.