arXiv subjects

Giovanni Calderini

Publications and source records attributed to Giovanni Calderini.

7 recordsLinked to original sources

arXiv2025

High Density Hybridisation Using ENIG Bumping and Anisotropic Conductive Films

Fine-pitch hybridisation processes are essential for next-generation pixel detectors and high-density microelectronic assemblies. Conventional bump-bonding techniques, although reliable, remain costly and difficult to implement for single-die applications. In this work, we present flip-chip hybridisation results combining Electroless Nickel Immersion Gold (ENIG) bumping with Anisotropic Conductive Film (ACF) bonding, both developed in-house. This method enables fine-pitch interconnections without requiring wafer-level processing. The feasibility of the ENIG-ACF process for functional devices was demonstrated by hybridising functional Timepix3 ASIC and Ti-LGAD (Trench Isolated Low-Gain Avalanche Detector) sensors with 55 um pitch. The approach was then extended to test structures with 25 um pitch, using aligned-particle ACFs. The analysis revealed that the main limitation originated from the mismatch between ACF thickness and bump height, underlining the importance of interface geometry optimisation. To address this, a dedicated simulation program was developed to model the isotropic growth of ENIG bumps and to determine the optimum bump height as a function of ACF thickness and pixel-matrix geometry. The results provide valuable guidelines for future high connection density assemblies and demonstrate the potential of the ENIG-ACF process as a scalable, low-cost alternative to conventional bump-bonding techniques.

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arXiv2024

Pixel detector hybridization and integration with anisotropic conductive adhesives

A reliable and cost-effective interconnect technology is required for the development of hybrid pixel detectors. The interconnect technology needs to be adapted for the pitch and die sizes of the respective applications. For small-scale applications and during the ASIC and sensor development phase, interconnect technologies must also be suitable for the assembly of single-dies typically available from Multi-Project-Wafer submissions. Within the CERN EP R&D program and the AIDAinnova collaboration, innovative and scalable hybridization concepts are under development for pixel-detector applications in future colliders. This contribution presents recent results of a newly developed in-house single-die interconnection process based on Anisotropic Conductive Adhesives (ACA). The ACA interconnect technology replaces solder bumps with conductive micro-particles embedded in an epoxy layer applied as either film or paste. The electro-mechanical connection between the sensor and ASIC is achieved via thermocompression of the ACA using a flip-chip device bonder. A specific pixel-pad topology is required to enable the connection via micro-particles and create cavities into which excess epoxy can flow. This pixel-pad topology is achieved with an in-house Electroless Nickel Immersion Gold process that is also under development within the project. The ENIG and ACA processes are qualified with a variety of different ASICs, sensors, and dedicated test structures, with pad diameters ranging from 12 μm to 140 μm and pitches between 20 μm and 1.3 mm. The produced assemblies are characterized electrically, with radioactive-source exposures, and in tests with high-momentum particle beams. A focus is placed on recent optimization of the plating and interconnect processes, resulting in an improved plating uniformity and interconnect yield.

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arXiv2017

Thin and edgeless sensors for ATLAS pixel detector upgrade

To cope with the harsh environment foreseen at the high luminosity conditions of HL- LHC, the ATLAS pixel detector has to be upgraded to be fully efficient with a good granularity, a maximized geometrical acceptance and an high read out rate. LPNHE, FBK and INFN are involved in the development of thin and edgeless planar pixel sensors in which the insensitive area at the border of the sensor is minimized thanks to the active edge technology. In this paper we report on two productions, a first one consisting of 200 μm thick n-on-p sensors with active edge, a second one composed of 100 and 130 μm thick n-on-p sensors. Those sensors have been tested on beam, both at CERN-SPS and at DESY and their performance before and after irradiation will be presented.

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arXiv2017

Performance of active edge pixel sensors

To cope with the High Luminosity LHC harsh conditions, the ATLAS inner tracker has to be upgraded to meet requirements in terms of radiation hardness, pile up and geometrical acceptance. The active edge technology allows to reduce the insensitive area at the border of the sensor thanks to an ion etched trench which avoids the crystal damage produced by the standard mechanical dicing process. Thin planar n-on-p pixel sensors with active edge have been designed and produced by LPNHE and FBK foundry. Two detector module prototypes, consisting of pixel sensors connected to FE-I4B readout chips, have been tested with beams at CERN and DESY. In this paper the performance of these modules are reported. In particular the lateral extension of the detection volume, beyond the pixel region, is investigated and the results show high hit-efficiency also at the detector edge, even in presence of guard rings.

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arXiv2016

The INFN-FBK Phase-2 R{\&}D Program

We report on the 3-year INFN ATLAS-CMS joint research activity in collaboration with FBK, started in 2014, and aimed at the development of new thin pixel detectors for the High Luminosity LHC Phase-2 upgrades. The program is concerned with both 3D and planar active-edge pixel sensors to be made on 6-inch p-type wafers. The technology and the design will be optimized and qualified for extreme radiation hardness (2e16 neq cm-2). Pixel layouts compatible with present (for testing) and future (RD53 65nm) front-end chips of ATLAS and CMS are considered. The paper covers the main aspects of the research program, from the sensor design and fabrication technology, to the results of initial tests performed on the first prototypes.

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arXiv2016

Performance of Edgeless Silicon Pixel Sensors on p-type substrate for the ATLAS High-Luminosity Upgrade

In view of the LHC upgrade phases towards the High Luminosity LHC (HL-LHC), the ATLAS experiment plans to upgrade the Inner Detector with an all-silicon system. The n-on-p silicon technology is a promising candidate to achieve a large area instrumented with pixel sensors, since it is radiation hard and cost effective. The paper reports on the performance of novel n-on-p edgeless planar pixel sensors produced by FBK-CMM, making use of the active trench for the reduction of the dead area at the periphery of the device. After discussing the sensor technology an overview of the first beam test results will be given.

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arXiv2013

Selected results from the static characterization of edgeless n-on-p planar pixel sensors for ATLAS upgrades

In view of the LHC upgrade for the High Luminosity Phase (HL-LHC), the ATLAS experiment is planning to replace the Inner Detector with an all-Silicon system. The n-on-p technology represents a valid solution for the modules of most of the layers, given the significant radiation hardness of this option and the reduced cost. There is also the demand to reduce the inactive areas to a minimum. The ATLAS LPNHE Paris group and FBK Trento started a collaboration for the development on a novel n-on-p edgeless planar pixel design, based on the deep-trench process which can cope with all these demands. This paper reports selected results from the electrical characterization, both before and after irradiation, of test structures from the first production batch.

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