Microscopic homogeneity of emitters formed on textured silicon using in-line diffusion and phosphoric acid as the dopant source

An important point of comparison between POCl3 emitter diffusion in a quartz tube furnace and in-line diffusion using sprayed phosphoric acid is the microscopic homogeneity of the diffusion, i.e. the homogeneity along the texture of a silicon surface. Two characterization methods were used. In each case, the cross-section of cleaved mc-Si and Cz-Si textured samples was observed in a scanning electron microscope (SEM). First, the thickness of the phosphosilicate glass (PSG) was measured. Second, the emitter was observed on SEM images which showed the n-type silicon as a darker region. The results show comparable homogeneity for in-line and POCl3 diffusion.