Development of Methanol Based Reactive Ion Etching Processes for Nanoscale Magnetic Devices

As feature sizes shrink to sub-50 nm for spin transfer torque (STT) devices and to sub-10nm for ultra-high density bit patterned media (BPM), anisotropic, defect free etching becomes difficult with conventional techniques, such as ion milling. Instead, reactive ion etching (RIE) must be used to meet the challenge. In this work, we present research on the development of a methanol based RIE technique for anisotropic etching of nanoscale magnetic and nonmagnetic STT and BPM related device structures with enhanced selectivity, minimal redeposition, and less faceting than similar structures etched with Ar ion milling. Using methanol RIE, we demonstrate magnetic film etch rates as high as 40nm/min and features as small as 20nm. These results, the promises of such a technique and the feasibility of etching sub-10nm dimensions are discussed in detail throughout the paper.