Development of Miniaturized Thin-Film Magnetic Field Probes for On-Chip Measurement

Abstract

We developed thin-film magnetic field probes with a high spatial resolution aiming to obtain the absolute value of a high-frequency power current on an LSI chip. The spatial resolution was enhanced by miniaturizing the shielded loop coil, which is the detection part of the probe. The minimum outer size of the new coil is 50 x 22 μm. In taking measurements with the new probe over a 60-μm-wide microstrip line used as a device under test (DUT), we found that the probe output decreases by 6 dB at a distance of 40 μm. This value is less than half that of our previous probe, which was around 100 μm. In taking measurements with the new probe over 5-μm-wide microstrip lines used as a DUT, we found that the new probe achieved 10-μm-class high spatial resolution. This value is comparable to the typical width of global power lines on an LSI chip, which ranges from 10 μm to 100 μm. We estimated the configuration of the lines on an LSI chip that would enable the new probe to achieve a spatial resolution high enough to obtain the absolute value of a high-frequency power current on an LSI chip.