A Nanoscale Plasma Etching Process for Pole Tip Recession of Perpendicular Recording Magnetic Head
Keywords:pole tip recession, plasma etching, selectivity, removal rate, ion damage
The pole tip of perpendicular recording head is constructed in a stacked structure with materials of NiCoFe, NiFe, Al2O3 and AlTiC. The surfaces of different materials are set at different heights below the air-bearing surface of slider. This paper presented a plasma dry etching process for Pole Tip Recession (PTR) based on an ion beam etching system. Ar and O2 mixed plasma at small incident angles have a high removal rate to the nonmagnetic material. It was utilised to etch the reference surface until it reaches the MT value. Low-energy Ar plasma at a small incident angle removes materials with selective ratios of 1 : 1.6 : 2.5 : 2.9 (AlTiC/Al2O3/NiCoFe/NiFe). It was selected to form the PTR. High-energy Ar plasma at a large incident angle exhibits almost same removal rates for all materials. It was adopted to make overall removal while keeping the recessed profile. An atomic force microscope (AFM) was used for measuring the recessed heights of pole tip and the MT value of the base surface. A transmission electronic microscopy (TEM) was chosen to examine the thickness of subsurface damage. A batch of production showed that the recessed heights can be successfully nanofabricated with the three-step plasma etching process.
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