Cryogenic current-in-plane tunneling apparatus.
We have designed and fabricated a cryogenic variable-temperature current-in-plane tunneling apparatus to measure the magnetoresistive properties of unpatterned magnetic tunnel junction wafers as a function of temperature. The wafer is mounted on the cold finger of a liquid helium continuous flow cryostat. The temperature can be continuously varied between 7 and 330 K. We describe the design and fabrication of the micromachined silicon probe head that comprises a comb of 20 measuring and 4 leveling probes. The measuring probes are typically 0.7 microm wide and 1.2 microm thick, with lengths of 10, 7, and 4 microm, and a pitch that varies from 1.5 to 30 microm. The leveling probes are used in conjunction with a tilt stage to adjust the parallelism between the comb and the sample wafer during the approach of the probe head. The probe head is mounted on a nonmagnetic x-y stage, which can access a 22x22 mm(2) area with a repeatability of approximately 1 microm. The first measurements taken at room and cryogenic temperatures are shown.
Weiss
Nicolas
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IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120-6099, USA.
Drechsler
Ute
U
Despont
Michel
M
Parkin
Stuart S P
SS