Microelectronic Engineering

Ion projection lithography for resistless patterning of thin magnetic films

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The ion projector at the Fraunhofer Institute in Berlin (manufactured by Ion Microfabrication Systems, IMS, Vienna) has been used to pattern thin magnetic films. Disordering of chemically ordered FePt films by patterned ion irradiation (dose: 1016 He+ ions/cm2; 75 keV) without a resist mask on the sample is demonstrated. Magnetically altered areas have been investigated by magnetic force microscopy. Magnetic islands of 340 nm width could be detected, limited by the size of the open stencil mask holes. The projector is capable of 50 nm resolution which would result in a storage density of 64 Gb/in2. In a second experiment the ion projector has been applied for structured ion milling with Xe+ ions on thin metallic films also without a resist mask. In a polycrystalline Au film 130 nm lines and spaces with a depth of 8 nm could be produced by a dose of 1015Xe+ ions at 75 keV energy.