Sputter Deposited Magnetostrictive Layers for SAW Magnetic Field Sensors

Area of Science:

• Materials Science
• Sensor Technology
• Magnetism

Background:

• Thin film properties are crucial for magnetic field sensor detection limits.
• Magnetostrictive layers in sensors require controlled composition, morphology, and stress.
• Quartz substrates can induce stress and magnetic anisotropy in deposited films due to temperature changes.

Purpose of the Study:

• To compare amorphous FeCoSiB films prepared by RF and DC magnetron sputtering for magnetic surface acoustic wave (SAW) sensors.
• To correlate film properties with SAW sensor performance metrics like phase noise and detection limit.
• To evaluate the impact of deposition method on material characteristics and sensor efficacy.

Main Methods:

• Amorphous FeCoSiB films were deposited using RF and DC magnetron sputtering.
• Material characterization included elastic recoil detection, X-ray diffraction, and magneto-optical magnetometry.
• SAW sensors were fabricated with deposited layers and their phase noise and detection limits were measured.

Main Results:

• Both RF and DC deposition methods yielded comparable magnetic field sensor detection limits below 200 pT/Hz^1/2 at 10 Hz.
• DC sputtering achieved higher deposition rates.
• Similar low substrate temperatures were maintained during both deposition processes.

Conclusions:

• DC magnetron sputtering is a viable alternative to RF sputtering for fabricating magnetostrictive films for SAW sensors.
• The DC method offers improved deposition efficiency without compromising sensor performance.
• Precise control over film properties during deposition is key to achieving high-performance magnetic field sensors.