Analysis of blister formation in spatial ALD Al2O3 for silicon surface passivation

Aluminum oxide (Al₂O₃) thin films yield excellent surface passivation of silicon solar cells. However, unwanted delamination, known as blisters, can occur upon annealing. In this research, blistering is linked to hydrogen diffusion in the bulk. Results reveal competition between diffusion lateral and perpendicular to the interface. Therefore, large blister densities coincide with small blister diameters and vice versa. The total blister volume, however, is independent of blister size distribution, but linked to hydrogen diffusion from the Al₂O₃ bulk. The blister volume was determined using AFM measurements, which show identical blister shapes for different blister sizes. Additionally, no direct relationship between blister formation and minority carrier was found.