The role and effect of residual stress on pore generation during anodization of aluminium thin films

• Al films of varying residual stress were prepared by sputtering.
• Variation of the residual stress in the Al films influences pore growth during anodization.
• The change in average pore size with residual stress is fairly small.
• Interaction of residual stress with oxide growth stress leads to change in structure.
• Residual tensile stress increases the pore density of porous alumina.

The role and effect of residual stress on pore generation of anodized aluminium oxide (AAO) have been investigated into anodizing the various-residual-stresses aluminium films. The plane stresses were characterised by X-ray diffraction with sin2ψ method. The pore density roughly linearly increased with residual stress from 64.6 (−132.5 MPa) to 90.5 pores/μm2 (135.9 MPa). However, the average pore size around 40 nm was not changed significantly except for the rougher film. The tensile residual stress lessened the compressive oxide growth stress to reduce AAO plastic deformation for higher pore density. The findings provide new foundations for realizing AAO films on silicon.