All-PMMA-based tunneling magnetic sensors were fabricated by hot embossing replication with silicon templates. The silicon templates had smooth surfaces, positive profiles, and pyramid-like pits with a high aspect ratio. With this fast (20 min), simple (one-step), and repeatable method, the all-PMMA tunneling sensor platform yielded sharp tunneling tips with 75 μm in baseline and 50 μm in depth. The sensors were assembled and fixed with measurement circuits, after their electrodes were patterned with modified photolithography and Co film was deposited with e-beam evaporation. A natural frequency response of 1.3 kHz was observed, and a tunneling barrier height of 0.713 eV was tested. Due to the quadratic relation between magnetic force and the field, the sensor field response (7.0 × 10 6 V/T 2) was also quadratic. The noise voltage at 1 kHz is 0.2 mV, corresponding to a magnet field of 0.46 × 10 -6 T. The bandwidth of this senor is 18 kHz. This new type of sensor platform is promising for the next generation of microsensing applications.
Bibliographical noteFunding Information:
Manuscript received April 28, 2004; revised April 26, 2005. This work was supported in part by the National Science Foundation/LEQSF under Grant (2001-04)-RII-02, in part by DARPA under Grant DAAD19-02-1-0338, and in part by NASA under Grant (2002)-Stennis-22. The associate editor coordinating the review of this paper and approving it for publication was Dr. Andre Bossche.
- Hot embossing
- Magnetic field sensor
- Tunneling sensor