Scissor sensor with back edge bias structure and novel dielectric layer
A scissor type magnetic sensor having an improved back edge bias structure. The back edge bias structure extends beyond the sides of the sensor stack for improved bias moment and is formed on a flat topography that provide for improved magnetic biasing. The sensor is formed by a method that includes first defining a sensor width and then depositing a multi-layer insulation layer that includes a dielectric layer that is resistant to ion milling and the depositing a fill layer over the dielectric layer that is removable by ion milling. After the multi-layer insulation layer has been deposited the back edge (i.e. stripe height) of the sensor is formed by masking and ion milling. This ion milling removes portions of the non-magnetic, electrically insulating fill layer that extend beyond the stripe height and beyond the sides of the sensor, leaving the dielectric layer there-beneath.
1. A magnetic sensor, comprising:
a sensor stack having a front edge located at an air bearing surface a back edge opposite the air bearing surface, and first and second laterally opposed sides, the sensor stack including first and second magnetic free layers that are magnetically anti-parallel coupled across a non-magnetic layer sandwiched there-between;
an insulation layer formed at the sides of the sensor and back edge of the sensor, the insulation layer being a material having an ion milling rate that is at least as great as that of the sensor stack the insulation layer being thicker at the sides of the sensor than at the back edge of the sensor; and
a magnetic bias structure formed at the back edge of the sensor stack over the insulation layer.
2. The magnetic sensor as in claim 1 , wherein the insulation layer is a bi-layer insulation structure comprising a first layer and a second layer formed over the first layer, and wherein the second layer and second layers are much thicker at the sides of the sensor than it is a the back edge of the sensor.
3. The magnetic sensor as in claim 1 , wherein the insulation layer comprises a first layer comprising one or more of MgO, SiN and SiON and a second layer comprising one or more of SiNx, TaOx, MgO and SiON.
4. The magnetic sensor as in claim 1 wherein the insulation layer comprises one or more of MgO, SiN and SiON.
5. The magnetic sensor as in claim 1 , wherein the insulation layer comprises MgO.
6. The magnetic sensor as in claim 1 , wherein the insulation layer comprises one or more of MgO, SiN and SiON and wherein the soft magnetic bias structure is formed over the insulation layer.
7. The magnetic sensor as in claim 1 , wherein the magnetic bias structure extends laterally beyond the first and second sides of the sensor stack.
8. The magnetic sensor as in claim 1 , wherein the magnetic bias structure has a width that is aligned with the sensor stack.
9. The magnetic sensor as in claim 1 , wherein the magnetic bias structure has a width that is self aligned with the sensor stack and wherein the sensor further comprises a soft magnetic side shield structure formed over the insulation layer and extending beyond a back edge of the sensor stack.