Junction engineering of microstrip silicon sensors to operate in controlled charge multiplication mode for enhanced radiation tolerance

该项目涉及利物浦大学高能物理（HEP）小组和美光半导体（英国）有限公司作为工业合作伙伴。利物浦集团在HEP实验硅探测器的研发、组装和调试方面拥有世界公认的记录。美光半导体有限公司是粒子物理实验硅探测器的领先供应商，拥有从固定目标计划到LEP， Tevatron, PEP-II， HERA和LHC的长期记录。然而，美光公司已经涉足太空（与美国国家航空航天局（NASA）和日本宇宙航空研究开发机构（JAXA）签订了合同）、国防、核和医疗应用领域，其中粒子物理仅占当前订单的20%左右。然而，这些其他领域的新技术和技术的发展历史上总是发生在迎接粒子物理挑战的背景下，当前的项目对公司和学生来说都是一个极好的机会。美光与利物浦大学长达15年的合作，为HEP实验生产了非常成功的硅传感器，如Tevatron-FNAL的CDF， CERN-LEP的DELPHI， CERN-LHC的ATLAS和LHCb。值得注意的是，第一个p型传感器，导致了n-in-p技术的发展，现在是sLHC的默认技术，源于利物浦和美光之间的CASE学生，学生Moshe Hanlon获得了卢瑟格伦奖的博士学位。论文的研究。这项工作将集中于优化硅探测器的设计和加工参数，通过在结侧形成电场来控制电荷倍增制度。在项目的第一阶段(a)，学生将使用TCAD和/或定制的电荷传输模型进行二维和三维设备模拟。利用现有文献和小组积累的实验数据，学生将实现辐射损伤硅的模型。辐照硅的性能是工业界和学术界都非常感兴趣的课题，能够访问大量的实验数据来与模拟进行比较，与专业工业合作伙伴合作对测试设备的深入了解，使独特的工作环境可能导致可发表的结果并增强制造方法。学生将使用最先进的套件设计光刻掩模，该套件将被工业合作伙伴采用以处理新设备。衬垫二极管、微带探测器、像素和用于过程控制和优化的各种测试结构将被设计和生产（阶段(b)）。任务(a)和(b)将在论文的第一学期在利物浦大学进行。接下来的阶段(c)将在第二学期开始，将涉及与公司的密切合作，以了解可以调整的加工参数，以实现结的精细成形。第一组晶圆（10-15）的生产将基于对当前加工参数的直观修改（在更陡峭和更光滑的轮廓的相反方向上），以探索更极端的结几何形状（阶梯或扩散结）及其辐照后的性能。第一批经过处理的探测器预计将在第二年的第一学期完成，同年年底将进行测量（由学生在导师的初步指导下进行）。这允许从测量反馈来纠正处理参数，验证和改进模拟与测量数据的信息。最终优化的几何形状将在去年进行处理和表征，并对参数进行微调。

This project involves the high energy Physics (HEP) group of the University of Liverpool and Micron Semiconductor (UK) Ltd as the industrial partner. The Liverpool group has a world recognised track record in R&D, assembly and commissioning of silicon detectors for HEP experiments. Micron Semiconductor LTd is a leading supplier of silicon detectors to particle physics experiments, having a long track record dating from fixed target programmes, to LEP, Tevatron, PEP-II, HERA and the LHC. However, Micron have diversified into work for space (with contracts with NASA,in USA and JAXA in Japan), defence, nuclear and medical applications with particle physics representing only about 20% of current orders. However, the development of new technology and techniques for these other areas has historically always taken place in the context of meeting the challenges of particle physics and the current programme represents an excellent opportunity for both the company and the student. The over 15 years long collaboration between Micron and the University of Liverpool has lead to the production of extremely successful silicon sensors for HEP experiments like CDF at Tevatron-FNAL, DELPHI at CERN-LEP, ATLAS and LHCb at the CERN-LHC. It is worth noting that the first p-type sensors, leading to the development for the n-in-p technology now the default for sLHC, grew out of a CASE studentship between Liverpool and Micron, for which the student, Moshe Hanlon, won the Rutherglen Prize for his PhD. thesis research. The work will focus on the optimisation of the design and processing parameters of silicon detectors to operate in a controlled charge multiplication regime by mean of the shaping of the electric field at the junction side. In the first phase (a) of the project the student will perform2-d and 3-d device simulations of the, using TCAD and/or custom made charge transport models. A model of the radiation damaged silicon will be implemented by the student using the existing literature and the experimental data accumulated by the group. The performance of irradiated silicon is a subject of high interest to both industry and academy, and the ability to access a substantial amount of experimental data to compare to the simulations, with the deep understanding of the tested devices coming from the collaboration with the specialised industrial partner makes a unique working environment likely to lead to publishable results and to enhanced manufacturing methods. The student will design the photolithography mask set using a state of the art package that will be adopted by the industrial partner for processing the novel devices. Pad diodes, microstrip detectors, pixels and various test structures for process control and optimisation will be designed (phase (b)) and produced. Both task (a) and (b) will be performed at the University of Liverpool during the first semester of the thesis. The following phase (c) will start on the 2nd semester and will involve close collaboration with the company to learn the processing parameters that can be tuned for a fine shaping of the junction. The production of a first set of wafers (10-15) will be based on intuitive modifications (in the opposite directions of a steeper and smoother profile) of the current processing parameters to explore more extreme junction geometries (step or diffused junction) and their performance after irradiation. The first processed detectors can be expected within the 1st semester of the 2nd year, with measurements (performed by the student under the initial guidance of the supervisor) taking place within the end of the same year. This allows for feedback from the measurement to correct the processing parameters, verify and improve the simulation with information from measured data. The finally optimised geometries will be processed and characterised in the last year, with fine tuning of the parameters.