A highly sensitive magnetic bubble detector in an essentially single-mask overlay

Abstract

A new field-access bubble detector is described and assessed in terms of signal-strength propagation margins and technology benefits. In this design the detection and propagation functions of the detector are separated by means of a sandwich structure. The so-called sandwich detector consists of a thin NiFe layer (detection), an insulation layer of SiO2, and a thick NiFe layer (propagation). The layers are structured with the aid of one mask (no alignment) while two gross masks (alignment accuracy within 25 μm) are used to create the connections to the detection layer. The measured sensitivity of a 35-chevron stretcher sandwich detector, designed for 7-μm bubbles (4π Ms=150 G), is 2 mV/mA.