Patterning Technologies for Magnetic Thin Films

Using EBL or ion beam lithography (IBL) a variation of shapes and dimensions can bee realized even down to 10 nm in size. With EBL large areas cannot be made accurately due to the problems with the long-range coherence of the e-beam writer and also the throughput is very low. But it is a very flexible method for the fabrication of nanostructures of arbitrary shapes for research [4]. Recently it has been shown that EB and IB projection methods can solve the problems with the throughput and mis-coherence 

Patterned media (e.g. section 4.1) can be fabricated from magnetic multilayers where ion irradiation is used to differentiate nanoscale magnetic islands in a magnetic matrix, without the removal of material from the multilayers [15, 16]. Arrays of Pt/Co/Pt dots with a dot separation of only 20 nm have been shown by FIB irradiation of 28keV Ga+ ions [17]. The magnetic effects can be influenced by the kinds of ions (He+, Ar+, Ga+, N+), their energies as well as their exposure doses (fluency). 

Another application of direct e-beam irradiation is given in [20]. In this paper, non-ferromagnetic Co-C thin films were magnetically patterned using a focused electron beam with a probe diameter of less than 0.1 pm. The 

In Fig. 4(A) it can be seen that the AFM dot size is almost independent on the dwell time (e-beam irradiation time) while the magnetic dot diameter (MFM) increases almost linearly with the square root of the dwell time. 

The dependence of square root of dwell time per dot , means that the magnetic dots are produced by heat-conduction- induced phase change in the 

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