AVS 50th International Symposium
    Processing at the Nanoscale Tuesday Sessions
       Session NS+MI-TuA

Invited Paper NS+MI-TuA1
Patterning Magnetic Recording Media by Imprinting

Tuesday, November 4, 2003, 2:00 pm, Room 308

Session: Nanoscale Patterning and Lithography
Presenter: G.M. McClelland, IBM Almaden Research Center
Authors: G.M. McClelland, IBM Almaden Research Center
M.W. Hart, IBM Almaden Research Center
M.E. Best, Hitachi San Jose Research Center
C.T. Rettner, IBM Almaden Research Center
K.R. Carter, IBM Almaden Research Center
G. Hu, Hitachi San Jose Research Center
B.D. Terris, Hitachi San Jose Research Center
M. Albrecht, Hitachi San Jose Research Center
Correspondent: Click to Email
Patterning magnetic media is a promising strategy for increasing magnetic recording density beyond the current value of 15 Gbit/sq. cm. As proposed by Chou, imprinting is an attractive means for generating the small structures required. This application is not affected by some difficult aspects of imprinting: overlay is not required, long range distortion is accommodated by positioning of the recording head, and defects can be corrected by error correction during read out. We have developed a complete, cost effective process for patterning of 30-nm-dia. single-domain magnetic islands over a 65 mm disk. The process steps are: forming a flexible stamp from a master, imprinting a replica in resist, reactive ion etching SiO2 pillars into the substrate, and depositing a magnetic film by evaporation. To accommodate the roughness and curvature of the substrate, a 10-micon-thick polymer stamp on an acrylic backing plate is used. The stamp is formed by photocuring an acrylate mixture in contact with an SiO2 master made by e-beam lithography. The resist is formed from a 15-nm-thick prepolymer liquid acrylate film spun onto the glass substrate. The film is viscous, so that non-flatness in the substrate is accommodate by stamp deformation, rather than by flow of the resist. After UV exposure, the stamp is removed to leave 30-nm-high resist pillars on a 10-nm-thick base layer. A dozen repeated imprints show a defect rate of about 1 in 10,000 pillars. A CF4/CH4 etch transfers the resist pattern into 30-nm-high, 30-nm-dia. SiO2 pillars with a period of 60 nm. To form a magnetic film, a 10-nm CoPt multilayer is deposited by e-beam evaporation at 300 K. This method shows promise for large-scale manufacturing, because the stamp-making process can be repeated indefinitely from a single master, and many replicas can be formed from each stamp.