Intrinsic limits of the sensitivity of CMOS integrated vertical Hall devices

Angular position device with 2D low-noise Hall microsensor

“…However, in parallel-field Hall structures the current paths are curvilinear and the kinetic processes are such that in magnetic field B Hall potentials are generated on all boundary surfaces of the chip, inclusive on the rear side. As shown in [15], there is transfer of the Hall voltage from the rear side via the lateral boundaries to the top chip plane while the substrate depth increases. In the general case, the measured Hall voltage V H 1,2 (B) with two Hall terminals H 1 and H 2 located at the top substrate plane is always reduced with respect to the entire Hall voltage V Hall (B) generated in the parallel-field Hall microdevice, V H 1,2 (B) = KV Hall , where the coefficient K is substantially <1.…”

“…The five-contact parallelfield Hall microsensors are found out to drastically reduce the internal 1/f noise by about three orders of magnitude since the biasing current does not flow through the Hall terminals [14]. Following from the numerous experimental results and the 2D FEM simulations and analysis carried out in [15], the shallower the CMOS parallel-field Hall device, the higher the short-circuit effect, and as a consequence, the magnetosensitivity and the signal-to-noise ratio will be reduced. As proven in [15] again, this microsensor class with two sensing contacts H 1 and H 2 are intrinsically limited in terms of measured transducer efficiency compared to the well-known Hall elements with orthogonal activation at equivalent doping level and thickness.…”

“…Following from the numerous experimental results and the 2D FEM simulations and analysis carried out in [15], the shallower the CMOS parallel-field Hall device, the higher the short-circuit effect, and as a consequence, the magnetosensitivity and the signal-to-noise ratio will be reduced. As proven in [15] again, this microsensor class with two sensing contacts H 1 and H 2 are intrinsically limited in terms of measured transducer efficiency compared to the well-known Hall elements with orthogonal activation at equivalent doping level and thickness. We believe that the major reason for this drawback is that in the classical Hall sensors, the current trajectories are linear with or without magnetic field B and the Hall field is situated between two well-defined sides of rectangular device designs.…”

“…Only in case of complete summing up of these Hall voltages could equality of the sensitivities in microsensors with orthogonal and parallel-field activation be achieved. If the parallel-field Hall device is deep enough, by using four separate sensing contacts only, H 1 -H 2 and H 3 -H 4 , located at the top side of the silicon chip, where one of the terminal pairs is located in the zone of the inside supply contacts [6,9,16], and the other terminal pair is located in the zone outside the supply electrodes [6,9,13], it is possible to achieve maximum sensitivity [15]. So far, in parallel-field Hall microsensors, the Hall voltage has been measured experimentally by two contacts, H 1 and H 2 , and in the elements with minimal design complexity -by one contact H [6,9,11,12,16].…”

Capteur ECG intelligent pour la synchronisation des séquences en IRM et le monitorage des patients

“…Les capteurs verticaux déve-loppés en technologie standard CMOS à cette occasion sont une réelle innovation technologique (Fig. 1b) [12][13][14][15].…”