| 摘要 |
A magnetoresistive sensor having magnetically anisotropic bias layers for biasing the free layer of the sensor. The sensor includes a sensor stack with a pinned layer structure and a free layer structure and having first and second sides. Hard bias structures for biasing the magnetization of the free layer are formed at either side of the sensor stack, and each of the hard bias structure includes a hard magnetic layer that has a magnetic anisotropy to enhance the stability of the biasing. The hard bias structure can include a Cr under-layer having a surface that has been treated by a low power angled ion milling to form it with an anisotropic surface texture. A layer of Cr-Mo alloy is formed over the Cr under-layer and the hard magnetic material layer is formed over the Cr-Mo alloy layer. The anisotropic surface texture of the Cr layer induces an aligned crystalline structure in the hard magnetic layer that causes the hard magnetic layer to have a magnetic anisotropy. In another embodiment, the hard bias structure can include a layer of Ta that has a surface formed with the anisotropic roughness. A layer of Cr-Mo alloy is formed over the Ta layer and the hard magnetic layer is formed over the Cr-Mo alloy layer. In yet another embodiment, the hard bias structure includes first and second Ta layers with a Si layer sandwiched between them. The second Ta layer has a surface treated with the anisotropic texture. A layer of Cr-Mo alloy can then be formed over the second Ta layer and the hard magnetic material formed over the Cr-Mo alloy layer.
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