| The microstructure and surface morphology of Cu thin films have been investigated and effects of microstructure and surface morphology on the patterning of microcircuits by wet chemical etching have been studied. Using 3 target DC magnetron sputtering unit, 2-5㎛ thick Cu thin films are deposited on the water-cooled substrates which are polycrystalline alumina, single crystal sapphire, and slide glass. 50㎚ thick Cr film is used as an adhesion layer between Cu and substrates. As the sputtering pressure increases, the microstructure is more open, and pores or microcracks in the column boundaries are frequently observed, which are in good agreement with the structure zone model proposed by Thornton. The morphology of Cu films deposited onto sapphire and slide glass substrates are similar at the same sputtering pressure, but the microstructure deposited on coarser polycrystalline alumina substrates contains more cracks and open boundaries, which are attributed to self-shadowing effcets during film growth. The micropatterns of 25㎛ in line width are successfully obtained by photolithography and wet chemical method regardless of sputtering conditions. Line morphology becomes smoother in the film formed at lower sputtering pressure. This effect is related to the open boundaries in the columnar structure. Line patterns are not much affected by grain or column size of the film. |
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