Practical realisation of a field-emission-based magnetic sensor

In this paper, the development of a functioning vacuum magnetic sensor (VMS), based upon the action of the Lorenz force on a field-emitted electron beam, is reported. The fabrication process is compatible with standard CMOS processes. It begins with the growth of a 2 μm thick oxide on a silicon substrate followed by the deposition of a 300 nm thick polysilicon layer. LOCOS is used to pattern that polysilicon layer to form a field-emitting tip as the cathode, surrounding extraction gate electrodes, and a split anode placed at distances between 1 μm and 500 μm from the cathode and gate (over 100 device variations were fabricated using the same mask). It should be noted that the LOCOS step serves the dual purpose of defining the polysilicon electrodes and tip sharpening.