Mathematical modelling and measurement of etching profile for junction shape control in MR read heads

A mathematical model was generated to predict the junction profile between MR element and hard bias element. Etching rates as a function of incident beam angle for relevant materials were experimentally determined for this model. Key process parameters such as stencil structure, ion beam angle, and MR element structure were varied. A series of experiments were made to confirm the model prediction by employing atomic force microscopy. We have found, for example, when the sidewall of a stencil was vertical, the junction angle became small resulting from the shadowing of incident ion beams. In addition, when a thin Ta layer was inserted between the MR element and bottom gap layer, the junction angle was increased.