Patent ID: 8216481

Claim:
A method for manufacturing a magnetoresistive sensor, comprising: forming a substrate; depositing a plurality of sensor layers onto the substrate; after depositing the plurality of sensor layers, depositing a first etch mask layer, the first etch mask layer being deposited to a thickness (T); depositing a second etch mask layer onto the first etch mask layer wherein the first etch mask layer is removable by reactive ion etching in a first chemistry and is resistant to removal by a reactive ion etching in a second chemistry, and the second etch mask is removable by reactive ion etching in the second chemistry and is resistant to removal by reactive ion etching in the first chemistry; depositing a bottom anti-reflective coating over the second etch mask layer; depositing a photoresist layer over the bottom anti-reflective layer; developing the photoresist layer to form a photoresist mask; transferring the image of the photoresist mask onto the bottom anti-reflective coating; performing a reactive ion etching in the second chemistry to transfer the image of the photoresist mask and bottom anti-reflective coating onto the underlying second mask layer; performing a reactive ion etching in the first chemistry to transfer the image of the second etch mask layer onto the underlying first etch mask layer; performing an ion milling process to form first and second side walls on the plurality of the sensor layers, the ion milling process being performed at various angles to form the sides as clean, uniform, well defined side walls and; after performing the ion milling, depositing a thin layer of insulation, then depositing a layer of hard magnetic bias material, then lifting off the first etch mask layer.