AMR vs. GMR Vs. TMR magnetic sensors
Many companies are working hard in the design, development and fabrication of Anisotropic Magneto-Resistance (AMR), Giant Magneto-Resistance (GMR), and Magnetic Tunneling Junction (MTJ) magnetic thin film sensors.
Working with a variety of magnetic materials (see table below) AMS deposition techniques achieve optimal conditions (uniformity, composition control, easy/hard axis orientation). The thickness range of these materials spans from <10Å (1nm) for GMR and MTJ applications to >10µ for magnetic shields and flux-concentrators.
|Materials||Magnetic Properties||Application||Deposition Technique||Typical Layer Thk.|
|NiFe (Permalloy)||Soft||AMR, GMR sensors||Sputtered||10Ǻ – 1000Ǻ|
|NiFe (Permalloy)||Soft||Shields, Poles||Plated||1µm – 10µm|
|NiFe (45/55)||Soft, higher moment||Shields, Poles||Plated||1µm-10µm|
|CoPt||Hard, high coercivity||Permanent magnets||Sputtered||500 Ǻ – 10 µm|
|Co ternary alloy||Soft, higher moment||Shields, Inductors, Poles||Sputtered||1 µm – 10 µm|
|IrMn, PtMn||Anti-ferromagnetic||GMR, MTJ sensors||Sputtered||50 – 250 Ǻ|
We use several different vacuum deposition tools to deposit a variety of magnetic materials, including the GMR / MTJ cluster disposition system seen below. The metrology equipment for the characterization of magnetic materials includes BH loopers, VSM (Vibrating Sample Magnetometer), MFM (Magnetic Force Microscopy) and RMM (Remanent Moment Magnetization).
Typical AMR transfer curve