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Toyoda N.,University of Hyogo | Yamada I.,University of Hyogo | Tani H.,Kansai University | Sakane Y.,Western Digital Media Operations
IEEE Transactions on Magnetics | Year: 2010

Irradiations of gas cluster ion beams (GCIB) on amorphous carbon films formed with chemical vapor deposition (CVD) were performed, and the affinity with lubricant was studied. The surface roughness of as-deposited amorphous CVD carbon film was improved with N2 -GCIB irradiation. By reducing the formation of multiply charged cluster ions, large crater formations can be minimized, which helps to obtain smooth surface. It was also shown that nitrogen rich surface was formed on the amorphous CVD carbon with N2 -GCIB. From the study of lubricant affinity and the surface free energy measurements, nitrogen containing functional groups were formed with N2-GCIB irradiation, as a result, adhesion between the lubricant and the amorphous CVD carbon film increased. © 2006 IEEE.


Nagato K.,University of Tokyo | Hoshino H.,University of Tokyo | Naito H.,University of Hyogo | Hirota T.,University of Hyogo | And 6 more authors.
IEEE Transactions on Magnetics | Year: 2010

We studied Ar gas cluster ion beam (GCIB) planarization effect on patterned surfaces refilled with Cr, Ta and SiO2. The patterns of 20 nm in depth were fabricated on Si substrate by using electron beam lithography and CHF3-reactive-ion-etching. The bit pattern pitches and the height of peak-to-valley were 150/200/300/400 nm and 20 nm, respectively. Then, refilling materials were deposited 30 nm in thickness on the patterned substrates. The test samples were irradiated by Ar-GCIB and the resultant surface profiles were measured by atomic force microscopy. Acceleration energy for a cluster was 20 keV. The dose was set from 2×1015to 5×10 15ion/cm2. Although there was a difference in the dose, the patterns disappeared clearly by irradiating GCIB. The reduction rate of peak-to valley height decreased with decreases of the pattern pitch. We indicated that GCIB irradiation is effective for the planarization of patterned surface refilled with Cr, Ta, and SiO2. © 2006 IEEE.


Nagato K.,University of Tokyo | Toyoda N.,University of Hyogo | Naito H.,University of Hyogo | Tani H.,Kansai University | And 4 more authors.
Journal of Applied Physics | Year: 2011

We studied the effect of the duty ratio, i.e., the ratio of hill width to pitch, of patterned diamondlike carbon (DLC) surfaces on Ar gas cluster ion beam (GCIB) planarization effect. The patterns of 40 nm depth were fabricated on Si substrates by electron beam lithography and CHF3 reactive-ion etching. The pitch of the line-and-space pattern was 300 nm and three duty ratios were adopted. Then, refilling materials were deposited to 50 nm thickness on the patterned substrates. The test samples were irradiated by Ar-GCIB and the resultant surface profiles were measured by atomic force microscopy. The acceleration energy for one cluster was 20 keV. The dose was set in the range from 5 × 1014 to 5 × 1016 ion/cm2. Although there was a difference in the dose, the patterns clearly disappeared upon irradiating GCIB. The reduction rate of the peak-to-valley height decreased as the width of the hill increased. We indicated that GCIB irradiation is effective for the planarization of patterned surfaces with various duty ratios. © 2011 American Institute of Physics.

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