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Robust insulating contiguous junction Disclosure Number: IPCOM000013584D
Original Publication Date: 2000-Jan-01
Included in the Prior Art Database: 2003-Jun-18

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Contiguous junctions have been used in magnetoresistive (MR) heads to provide longitudinal biasing and electrical interconnection. A contiguous junction is usually fabricated by milling the sensor layer, depositing bias and lead materials over the MR milling mask, followed by a lift-off process. For some new read sensor configurations, such as tunneling junction sensor or sensor with flux guide, an insulating contiguous junction needs to be fabricated. For an insulation contiguous junction, the biasing (or flux guide) material is separated from the sensor by a thin layer of insulator. As a result, the longitudinal biasing (or flux transfer) is achieved by the magnetic coupling through the insulation film while no current shunting occurs through the junction. However, fabricating such a junction is difficult since an extremely thin insulation layer can destroy the required magnetic coupling. Furthermore, the thinning of the insulation on the sensor sidewalls and below the resist photo mask also weakens the insulation. Disclosed is a junction fabrication method that improves the junction insulation. In the disclosed method, a sensor stack is first deposited. On top of the sensor stack, a metal layer, such as Ta, Ti, or Cr, which forms a tenacious oxide in oxygen plasma, is deposited. The metal layer is then oxidized in an oxygen plasma. Track-defining photo and milling processes are then performed. After the ion milling process, a plasma oxidation process is again used to oxidize the sidewalls of the sensor. After this process, the sensor top and the sidewalls are surrounded by the plasma oxide. A thin layer of dielectric material is then deposited followed by the bias (or flux guide) deposition. Because of the presence of the plasma oxide, the insulation between the bias (or flux guide) material and the sensor is drastically improved. 1