Magnetic mesa structures fabricated by reactive ion etching with CO/NH ₃/Xe plasma chemistry for an all-silicon quantum computer

Micromachining of magnetic materials is becoming a crucial technology for future magnetic systems/devices such as high-density magnetic recording heads, high-density patterned media, magnetic quantum devices, and micro-magnetic smart systems. NiFe alloy, one of the typical ferromagnetic materials, can be deposited and fabricated using current thin film and micromachining technologies, and it has found various applications in microsensors, microactuators, and microsystems. In our recent work, Ni₄₅Fe ₅₅ alloy with the highest saturation magnetic-flux density was selected as the micro-magnet for an all-silicon quantum computer. The micro-magnet was designed to create a large magnetic field gradient and to distinguish ²⁹Si nuclear spins arranged as chains in a ²⁸Si matrix with Larmor frequencies. This paper reports the micromachining of a Ni₄₅Fe₅₅ alloy mesa structure for an all-silicon quantum computer and the preliminary evaluation of its effectiveness using a magnetic force microscope (MFM) and a superconducting quantum interference device (SQUID).