A study of blister formation in ALD Al<inf>2</inf>O<inf>3</inf> grown on silicon

Fracture properties of atomic layer deposited aluminum oxide free-standing membranes

“…42,43 It has been reported that hydrogen and oxygen contents are reduced during annealing. 42,43 Moreover, annealing induces changes in stress level that can lead to failure. Indeed, some of our membranes failed after annealing without any mechanical load (25-30% of samples).…”

Large-Area n-Type PERT Solar Cells Featuring Rear p+ Emitter Passivated by ALD Al2 O3

“…Instead, the passivation quality was found to be mostly determined by the temperature of the PDA [34], rather than by the gas ambient. This can be explained by the fact that thermal ALD-deposited Al 2 O 3 contains already a relatively large amount of hydrogen [35], which increases with decreasing deposition temperature and is estimated to be in the range of 2-5 at% for a deposition temperature of 200°C [36]. Hydrogen starts to diffuse in Al 2 O 3 already at temperatures below 300°C (in atomic or molecular form, depending on the density of the layer [37]) and can effectively passivate the dangling bonds at the Si interface.…”

Blistering mechanisms of atomic-layer-deposited AlN and Al2O3 films

“…6 Most studies regarding blistering of ALD films deal with Al 2 O 3 as it is one of the most thoroughly characterized ALD material and since it provides excellent passivation of Si-based solar cells. [6][7][8][9] The passivated solar cells undergo a firing step to improve the interfacial quality between the Al 2 O 3 film and the Si substrate, after which the semispherical defects appear on the film. The blistering is thought to be caused by desorbing H 2 and H 2 O vapor that gets trapped between the substrate and the film.…”

“…The blistering is thought to be caused by desorbing H 2 and H 2 O vapor that gets trapped between the substrate and the film. 9 The ALD film acts as a gas diffusion barrier, while the interfacial gas pressure grows finally causing local delamination and bulging of the film. However, recently Xie et al 10 showed that in order to initiate the delamination and the blister formation from a nm-order defect site, an unrealistically high gas pressure of tens of gigapascals would be required.…”