Response surface study of resist etching in high density oxygen plasma and interactions of O2 plasma with NiFe, Cu, Ta, and Al2O3

Abstract

Etching of a photosensitive polymer in high density oxygen plasma was studied. The polymer is a commonly used insulation material in a magnetic recording head. A quantitative relationship between etch rate and inductive power, bias power, and pressure was established by using the response surface method. Etch rate was found to increase with both inductive power and bias power, and a maximum etch rate was found at about 5 mTorr pressure. The effect of exposing the commonly used materials in magnetic recording heads such as NiFe (81/19 wt %), Cu, Ta, and Al2O3 to high density oxygen plasma was also investigated. Electron spectroscopy for chemical analysis and Rutherford backscattering spectroscopy were used to characterize the plasma-exposed samples. It was found that exposure to high-density oxygen plasma caused rapid oxidation of Cu, segregation and oxidation of Fe at the surface of NiFe, relatively slight oxidation of Ta, and no change in the physical thickness or the composition of Al2O3.