Patterned films by atomic layer deposition using Parafilm as a mask

Abstract

This paper presents a new method for depositing patterned films by atomic layer deposition (ALD) using Parafilm as a mask to block the film growth on selected areas of the substrate surface. This offers an easy and efficient method for large area patterning from the millimeter to even meter scale as needed, for example, for protecting contact areas in integrated circuits and microelectromechanical system devices and in preventing film growth on the backside of substrates. It is shown here that Parafilm can protect the substrate against Al2O3, TiO2, and Ir film growth effectively. However, outgassing from the Parafilm affects the film growth on the unmasked areas differently for the three materials. For Al2O3, there are no significant effects on the growth rate and film quality on the nonmasked areas and the thickness profiles next to the Parafilm masked areas are narrow. For TiO2 and Ir, by contrast, the thickness profiles are wider and outgassing also slows down the Ir growth. Energy dispersive x-ray analysis confirms that Ir does not grow on Parafilm. Al2O3 and TiO2 films do grow on Parafilm, but after the ALD process, the Parafilm can be peeled off easily with tweezers and the areas under the Parafilm mask are without any deposition.