Description du sujet de thèse

A new generation of Monolithic CMOS pixel sensor or MAPS is being developed for the need of high energy physics experiments beyond 2030. Such MAPS will feature unprecedented performance among which: position resolution below 3 µm, time resolution in the 100 ps range, hit rate capability exceeding few 100 MHz/cm2 and radiation tolerance beyond 1e16 neutrons (1MeV equivalent)/cm2.

The design of these sensors involves precise simulation that encompasses both the physics of sensing in silicon and the behavior of the electronic microcircuits. Today, these models are carried out with separate tools. For example GEANT4 and Allpix2 are software used to predict the primary signal of a pixel, generated by the passage of a particle. The behavior of microcircuits is modeled by proprietary algorithms in IC design software (e.g. CADENCE). The current connection between these two types of simulation is based on very simplified parametrized functions of the pixel signal and do not allow to verify precisely if the sensor will be able to reach the very high performances mentioned above.

This thesis work ambitions to create the first complete and detailed simulation chain from the initial interaction of the particle with the silicon to the sensor output data flow and to demonstrate its benefits on a specific sensor concept. Such exhaustive modeling requires to understand both simulations at the detection level and at the circuit level. The articulation between the two simulation environments, i.e. physical and electrical simulation, will be done through the development of a compact model allowing the reduction of simulation times necessary for microelectronic design. The compact model could be developed through neural networks and machine learning in order to produce a model in a language that can be used by design tools such as Verilog-A. The first approach will consist in tuning the complete method on existing monolithic pixel sensors available at IPHC by comparing measured performances (on position, time and energy resolutions) with the simulation. In a second step, the method will be applied to sensors in the design phase, which targets the performance listed above, and in collaboration with the micro-electronic designers. One fabricated, the test of these advanced sensors will allow additional improvements of the simulation tools.
Practically, the doctoral student will engage in the following activities: sensor testing including data analysis, signal generation simulation and sensor electronic behavior simulation. Depending on the student profile, the weight on each activity could be adapted. The outcome of the thesis will be a complete methodology based on existing and other newly created tools allowing to predict the main performance of monolithic pixel sensors at an unprecedented level as well as some prototypes of these sensors.

Contexte de travail

The Institut Pluridisciplinaire Hubert CURIEN (IPHC), a joint research unit under the joint supervision of CNRS and the University of Strasbourg (UMR7178), is a multidisciplinary laboratory where research teams from different scientific cultures (ecology, physiology and ethology, chemistry and subatomic physics) develop very high level programs based on scientific instrumentation. The IPHC is structured into 4 departments and has a total staff of 393 staff including 257 permanent staff (ie 119 researchers and teachers / researchers and 138 engineers and technicians), 46 staff on fixed-term contracts and 90 doctoral students.
The doctoral student will work within the core facility C4Pi of IPHC. With about twenty engineers, post-doctorant fellows and PhD students, the C4Pi is a major group on the international stage for the development of CMOS pixel sensors (MAPS) for the detection of charged particles dedicated to high-energy physics. C4Pi collaborates with various groups at the national level and with the large world laboratories like CERN (Geneva), DESY(Hamburg) and KEK(Tsukuba).
The PhD student will benefit from a dynamic environment where different R&D projects are on-going, which allows for frequent chip fabrications. C4Pi also offer powerful test equipments to characterise prototypes.

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.

Informations complémentaires

With a Master's degree or an engineering degree specializing in microelectronics and more particularly in digital electronics, the candidate must be able to communicate in scientific English (level B2 according to the Common European Framework of Reference for Languages), and have good aptitudes for working in an international collaboration (contributions to a collective project, meetings and missions outside the laboratory).