Investigation of chemical etching of AlN film with different textures by x-ray photoelectron spectroscopy

The chemical etching of AlN films with the texture of the (0 0 2) and (1 0 0) planes has been investigated. The chemical states of the films before and after etching were particularly focused on. The AlN films were prepared by sputtering and etched in KOH solution. It is found that the etch rate, etched surface morphology and the surface chemical state depend on the film's different textures. The etch rate of the film with (1 0 0) texture is higher than that of the (0 0 2) orientated film, while the latter exhibits homogeneous pyramids of triangular shape on the etched surface. Some changes were observed in the x-ray photoelectron spectroscopy (XPS) after etching, including the reduction of the Al–O component, the enhancement of the O–H component and the appearance of the N–H component. Based on the XPS results, the appropriate mechanisms of the chemical etching for films with (0 0 2) and (1 0 0) textures have been proposed. The etching can be continued by the attractive effect between OH− ions and Al atoms as well as dissolving the in-process product of aluminium oxide.