Self-aligned surface modification for magnetochemical sensors

A method of fabricating a device for detecting magnetic particles, the method comprising:

• depositing a sensor stack on a wafer;
• situating a mask over the wafer;
• depositing an electrode over the sensor stack;
• while the mask is in place, depositing a reactive layer over the electrode;
• and
• functionalizing the reactive layer to attract the magnetic particles to the reactive layer.

A detection device for detecting magnetic particles, comprising:

• a sensor stack, comprising:
• a magnetochemical sensor, and
• a reactive layer;
• a trench adjacent to the sensor stack and exposing the reactive layer;
• and
• a functionalized surface within the trench, wherein the functionalized surface is configured to direct the magnetic particles toward the sensor stack.

A method of fabricating a device for detecting magnetic particles, the method comprising:

• depositing a sensor stack, the sensor stack comprising:
• a first ferromagnetic layer,
• a second ferromagnetic layer,
• a non-magnetic spacer layer situated between the first ferromagnetic layer and the second ferromagnetic layer, and
• a reactive layer comprising a reactive metal;
• creating a trench adjacent to the sensor stack, thereby exposing the reactive layer;
• and
• functionalizing a surface within the trench to direct the magnetic particles toward the sensor stack.