Air bearing surface recessed steep wall via optical proximity correction mask and fluorine-based plasma etching

• Published in: Surface & coatings technology 2016-11, Vol.306, p.299-304
• Main Authors: Pakpum, C., Pussadee, N.
• Format: Article
• Language: English
• Subjects: Air bearing surface; Air bearings; Al2O3-TiC (AlTiC); Byproducts; Etching; Fluorine-based plasma; Masks; Optical proximity correction mask; Patterning; Photoresists; Slopes; Steep Wall angle; Walls
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2016.06.072

Etched steep wall is very difficult to achieve by fluorine-based Reactive Ion Etching (RIE) process on Air Bearing Surface (ABS) made of alumina titanium carbide (Al2O3-TiC or AlTiC). The ideal wall angle of a fly height target for read/write slider head would be perfectly vertical, however the fabricated patterns normally ends up in slope etched wall of AlTiC. Also, shallow etched ABS walls cause great variation in fly height between inner and outer radii of recording disk when performing data reading or writing. It is necessary to develop etching method that results in steep and clean etched wall of AlTiC substrate. In this study, the effect of photoresist mask angle prior to RIE process on degree of slope etched wall was explored. The goal was to have the etched angle steeper than 40° and re-deposition free etched wall. Sloped wall variation in photoresist was accomplished using optical proximity correction (OPC) mask. Due to technical difficulty in photoresist patterning, the angles of patterned photoresist achieved were between 30°–65° and 70°–90°. It was found that with photoresist's angles between 30°–65°, the etched wall angles of AlTiC were less than 40° and no re-deposition of by-product was observed. With the resist's angle between 70°–90°, the etched wall angles exceed 40° but the built-up byproduct deposition was observed. It is suggested that the photoresist's angles of 65°–70°could provide desired etched angle and clean etched wall. Further development of photoresist patterning technique is required to produce photoresist wall angles of 65°–70°. •Slope wall photoresist was fabricated using optical proximity correction mask technique.•Slope photoresist wall acts as supporting surface for etch byproducts redeposition, later sputtered off by physical etching.•For small photoresist wall angle, etched AlTiC substrate is redeposition free with small etched wall angle.•For 70°–90° photoresist wall angles, etched AlTiC wall angle exceeds 40° but etch byproduct redeposition was observed.