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In this summary we present a novel approach to particle detection and track reconstruction for HEP (High Energy Physics) vertex experiments based on 3D IC pixel detectors. Our approach is based on the superposition of several monolithic detectors including both sensing area and control/signal elaboration circuitry, integrated in a 3D stack by means of intra-silicon vertical connections. Each layer consists in a fully functional sensor derived from already fabricated and tested 2D CMOS Active Pixel vertex detectors, manufactured using a commercial sub-micron CMOS VLSI technology.

Such layers could be thinned down and then stacked in a monolithic device through silicon vias (TSV) connections. Such a detector configuration has been extensively simulated by means of physical prediction tools (Sentaurus, GEANT4), and a first prototype (featuring two superposed tiers with a front-to-front coupling) has been designed using a 130nm CMOS technology, containing a 5000 square microns sensitive area and several test structures, as well as an ad-hoc developed standard cell set; it is currently under production and first prototypes will be available at mid-2010.

A more complete prototype, featuring a 7 square millimeters sensitive area and the possibility of a higher number of stacked tiers has been designed and will be submitted during 2010. Negligible multiple scattering effects are expected to happen in such a structure (since incoming particles have to cross only 12 microns of bulk silicon and about 10 microns of silicon oxide) with respect to bump-bonded non-monolithic sensor stacks conventionally used for track reconstruction, where incoming particles have to cross several millimeters of material, thus increasing the scattering risk.

According to simulation results, the information coming from the thinned, spatially close stacked layers could be usefully exploited to extend the detection capability of the monolithic sensor, achieving a spatial resolution of the crossing point in the micrometer range. Also according to simulation results, such a structure could be used to achieve an accurate estimation of the particle incidence angle, with angular precision down to the tens of milliradian range, depending on the number of superposed tiers and on the impact point/tilt of the incoming particle.

Cite as

A. Marras et al., “Design of a Monolithic Momentum Detector using a 3D IC Vertical Integration Approach” presented to the conference  “Vertically Integrated Pixel Sensors (VIPS), Pavia (Italy). April 22-24, 2010”.5