Hybrid exposure strategy: Combining e-beam direct writing with optical lithography for magnetic recording heads

Abstract

Hybrid exposure strategies have been implemented with commercially available chemically amplified resists for the fabrication of magnetic recording heads. This approach relies on splitting the pattern into high-resolution and low-resolution components at the same resist level. Two critical features of the thin-film head (TFH) device (write top pole and read sensor widths) are defined by e-beam direct writing for the high-resolution patterning, and all other, relatively large features, are patterned with optical lithography for high throughput. In this article we will present the results from the fabrication of sub-50nm magnetic write and read components with this hybrid exposure process. Key lessons from many aspects of the process development effort will be discussed in relation to TFH fabrication, including dual sensitive resist selection, exposure sequence, postexposure delay effect, e-beam process challenges, and overlay alignment issue. We demonstrate the capability of printing top pole structures with pole widths of sub-40nm in a 0.35-μm-thick resist film (aspect ratio>8:1), and electroplated top pole structures of 40nm with CoFe.