Assembly of heterogeneous full-custom integrated circuits in high-reliability components allows to create innovative functions in miniature systems, especially in the field of detection and imaging. Whatever the field of application (space science, synchrotron imaging spectrometers applied to X-ray fluorescence, medical imaging, additive manufacturing monitoring, …), the density of electronics is growing up and embedded systems are more and more complex, mixing analog and digital blocks, to offer progressively highly autonomous functions. This is also the trend for imaging spectrometers in the hard X-ray range.
Our team proposes to unlock a disruptive technology for high density, large scale, highly reliable manufacturing of CdTe based hard X-ray imaging spectrometers based on a wafer-level plastic packaging by compression molding technique to stack electronic functions in 3D. The principle is based on the construction of a mosaic of screened front-end ASICs embedded into a polymer matrix to form a flat and large plane of circuits whereon the pixelated detector is flip chipped. The layer obtained is processed with a wire free technology to bring the necessary I/O’s at the back side using a laser grooving process, is stacked and interconnected to further circuitry such as power supply filters, thermo-mechanical carriers and analog-to-digital converter stages. The module is finished with an interconnection layer. The front-end circuits are placed on 2´2 ASIC array, forming a large surface 4 times larger than the unit circuit size. As a reticule is approximately 2´2 cm2, a large crystal covering 4´4 cm2 can be achieved without any Through-Silicon-Vias (TSV). Minimising the surrounding I/O pads rings surface, larger mosaic can be engineered with limited dead zones.
The breakthrough relies on the use of a wafer-level process to build a 3D detection module package offering both high performance and low dead zones in the sensitive area. This technology allows the use of circuits extracted from Multi Projects Wafers, the sole reasonable economic way for the labs to access deep submicron technologies. On the long run, commercially available deep submicron technology enables the design of ultra-fine pitch imagers (~100 μm) with excellent spectral response. In addition, the absence of TSV makes the process easily adaptable to different microelectronics technologies and particularly appropriated for multi-technology devices.
This ATTRACT project is a unique opportunity to unlock key technological locks to accelerate the deployment of this European technology. This project is a cross-cutting project of Component manufacturing technology, Micro Technologies and Sciences (application to an X-ray or charged particle detection system for research in physics, astronomy and medical imaging). This technology can be applied to many applications where sensor arrays have to be mounted on top of a large front-end electronics plane with minimal dead zones.