I. Introduction
Micromachined Lorentz force magnetometers are receiving considerable attention in the sensing community, as they can be fabricated without requiring any custom magnetic materials (e.g., integrated permanent magnets in [1]). This allows for their co-fabrication alongside other MEMS sensors on the same chip, for augmented functionality with minimum impact on form factor. Such integration is highly attractive for consumer electronics applications, where MEMS sensors are playing an increasing role each day. In such cost-sensitive applications, exotic magnetic materials often do not justify the added costs and fabrication complexity, and limit the compatibility of magnetometers with other MEMS sensing structures and integrated circuits (ICs). In [2], an out-of-plane Lorentz force magnetometer and a ferromagnetic in-plane nickel magnetometer are presented, requiring high temperature fabrication steps (e.g., 800 °C), while, in [3] and [4], a Lorentz force-based resonant sensor for in-plane or out-of-plane magnetic fields is built using SOI technology. While two similar orthogonal structures could be used for 3D sensing, these devices are not suitable for post-CMOS monolithic integration. In [5], a co-fabricated CMOS-MEMS magnetometer is presented in a TSMC 0.35 m technology, but is restricted to the materials and constraints inherent to that semiconductor process node.