Design and characterisation of monolithic CMOS detectors for high energy particle physics and SEU radiation tests for ATLAS Inner Tracker Upgrade readout chip

This thesis covers the characterisation results and the design of monolithic CMOS detectors designed in TowerJazz 180nm CMOS technology for High Energy Particle Physics applications. Three different detectors have been studied the MALTA, the Mini-MALTA and the MALTA2. The MALTA sensor showed some efficiency losses at the corners of the pixels after irradiation, which meant that it was not suitable for the radiation environments in which it was supposed to be installed. Therefore, the front-end electronics and the fabrication process were modified to overcome this issue. The Mini-MALTA prototype was designed including the above mentioned improvements, fabricated and fully characterised. Finally taking into account all the knowledge acquired during these years of developments another large scale sensor the MALTA2 has been produced which should be radiation tolerant and have very good time resolution. The description and studies of the different architectures used in this family of detectors are covered and a simulation to estimate the bandwidth capabilities have been reported. Furthermore, this work will present characterisation of single event effects in the ITkPixV1, the prototype version of the ATLAS Inner Tracker Upgrade chip for the High Luminosity LHC. Measurements were made in testbeam campaigns with high energy ions and protons to evaluate the level of single event effects in the chip

Radiation hardness of MALTA2 monolithic CMOS imaging sensors on Czochralski substrates

MALTA2 is the latest full-scale prototype of the MALTA family of Depleted Monolithic Active Pixel Sensors (DMAPS) produced in Tower Semiconductor 180 nm CMOS sensor imaging technology. In order to comply with the requirements of high energy physics (HEP) experiments, various process modifications and front-end changes have been implemented to achieve low power consumption, reduce random telegraph signal (RTS) noise, and optimise the charge collection geometry. Compared to its predecessors, MALTA2 targets the use of a high-resistivity, thick Czochralski (Cz) substrates in order to demonstrate radiation hardness in terms of detection efficiency and timing resolution up to 3 × 1015 1 MeV neq/cm2 with backside metallisation to achieve good propagation of the bias voltage. This manuscript shows the results that were obtained with non-irradiated and irradiated MALTA2 samples on Cz substrates from the CERN SPS test beam campaign from 2021 to 2023 using the MALTA telescope

Performance of the MALTA Telescope

MALTA is part of the Depleted Monolithic Active Pixel sensors designed in Tower 180nm CMOS imaging technology. A custom telescope with six MALTA planes has been developed for test beam campaigns at SPS, CERN, with the ability to host several devices under test. The telescope system has a dedicated custom readout, online monitoring integrated into DAQ with realtime hit map, time distribution and event hit multiplicity. It hosts a dedicated fully configurable trigger system enabling to trigger on coincidence between telescope planes and timing reference from a scintillator. The excellent time resolution performance allows for fast track reconstruction, due to the possibility to retain a low hit multiplicity per event which reduces the combinatorics. This paper reviews the architecture of the system and its performance during the 2021 and 2022 test beam campaign at the SPS North Area

Performance of the MALTA telescope

MALTA is part of the Depleted Monolithic Active Pixel sensors designed in Tower 180 nm CMOS imaging technology. A custom telescope with six MALTA planes has been developed for test beam campaigns at SPS, CERN, with the ability to host several devices under test. The telescope system has a dedicated custom readout, online monitoring integrated into DAQ with realtime hit map, time distribution and event hit multiplicity. It hosts a dedicated fully configurable trigger system enabling to trigger on coincidence between telescope planes and timing reference from a scintillator. The excellent time resolution performance allows for fast track reconstruction, due to the possibility to retain a low hit multiplicity per event which reduces the combinatorics. This paper reviews the architecture of the system and its performance during the 2021 and 2022 test beam campaign at the SPS North Area

Radiation hardness of MALTA2 monolithic CMOS imaging sensors on Czochralski substrates

MALTA2 is the latest full-scale prototype of the MALTA family of Depleted Monolithic Active Pixel Sensors (DMAPS) produced in Tower Semiconductor 180 nm CMOS sensor imaging technology. In order to comply with the requirements of high energy physics (HEP) experiments, various process modifications and front-end changes have been implemented to achieve low power consumption, reduce random telegraph signal (RTS) noise, and optimise the charge collection geometry. Compared to its predecessors, MALTA2 targets the use of a high-resistivity, thick Czochralski (Cz) substrates in order to demonstrate radiation hardness in terms of detection efficiency and timing resolution up to 3 × 1015 1 MeV neq/cm2 with backside metallisation to achieve good propagation of the bias voltage. This manuscript shows the results that were obtained with non-irradiated and irradiated MALTA2 samples on Cz substrates from the CERN SPS test beam campaign from 2021 to 2023 using the MALTA telescope

Radiation hard monolithic CMOS sensors with small electrodes for the HL-LHC and beyond

The upgrade of tracking detectors for experiments at the HL-LHC and future colliders requires the development of novel radiation hard silicon sensors. We target the replacement of hybrid pixel detectors with Depleted Monolithic Active Pixel Sensors (DMAPS) that are radiation hard monolithic CMOS sensors. We designed, manufactured and tested DMAPS in the TowerJazz 180 nm CMOS imaging technology with small electrodes pixel designs, that have a pixel pitch well below the current hybrid pixel detectors, and less multiple scattering due to a reduced total silicon thickness. In this document we present the recent results from these sensors manufactured on Czochralski silicon substrates in terms of cluster size, impact on tracking and time resolution from measurements carried out at beam tests on irradiated samples at 1e15 1 MeV $\mathrm{n}_\mathrm{eq}/\mathrm{cm}^{2}$

MALTA: a CMOS pixel sensor with asynchronous readout for the ATLAS High-Luminosity upgrade

Radiation hard silicon sensors are required for the upgrade of the ATLAS tracking detector for the High-Luminosity Large Hadron Collider (HL-LHC) at CERN. A process modification in a standard 0.18 μm CMOS imaging technology combines small, low-capacitance electrodes (~2 fF for the sensor) with a fully depleted active sensor volume. This results in a radiation hardness promising to meet the requirements of the ATLAS ITk outer pixel layers (1.5×10$^{15

X-Ray measurements of radiation hard monolithic CMOS sensors at Diamond Light Source

This contribution outlines the results of investigations into the effects of radiation damage in the mini-MALTA depleted monolithic pixel sensor prototype using a micro-focus X-ray beam at Diamond Light Source. The in-pixel photon response was measured for three different pixel design variations: one with the standard continuous $\mathrm{n^-}$ layer layout and standard front-end, and extra deep p-well and $\mathrm{n^-}$ gap designs with a modified front-end. The standard design showed a decrease of 12\% in pixel response after irradiation to 1e15 $\mathrm{n_{eq}/cm^2}$. The two new designs did not show a significant decrease in pixel response after irradiation