Development of Designs, Processes and Technology for 200mm Silicon Sensors

Siliconbased detectors are central to all modern particle physics collider experiments. The functional area of these systems has increased from a few square centimeters in the mid80s to 200 square meters for the CMS tracker in the early 2000s. Upgrades being considered for the high luminosity LHC will require more than 200 square meters for CMS and ATLAS experiments and over 600 square meters for the proposed CMS High Granularity Calorimeter. In spite of this huge increase, silicon sensors are still being made on 4" or 6" wafers; building them on larger wafers would reduce both overall cost and the number of modules needed. The sensors must also be radiation hard, which implies thin (~100 micron) sensitive regions to minimize bias voltage. Producing thin, large area sensors is a significant challenge that must be solved for the next generation of trackers. Tezzaron proposes to develop the capability to produce thin silicon detectors with large area (200mm) wafers at its wholly owned subsidiary foundry, Novati Technologies, in Texas. This effort extends work currently underway, funded by the DoE Phase I grant, that has demonstrated baseline production of sensors for the CMS tracker and High Granularity Calorimeter. Phase I incorporates designs from Fermilab, SLAC, and Argonne. In Phase II Tezzaron will use designs developed in collaboration with other groups coordinated by Fermilab. We will demonstrate the production of thin, large area, radiation hard sensors with enhanced polysilicon bias resistors and AC coupled strips incorporating MIM capacitors. Beyond improving the baseline process, Tezzaron will create a Product Development Kit (PDK) to enable widespread user adoption and support. In Phase I, Tezzaron fabricated sensor prototypes on six wafers processed with variations in implant, wafer thickness, and thinning processes. Earlier work was improved upon by adding a Pstop to the designs and wafer processing flow. The results are good except for low breakdown voltage from one of the thinning techniques employed. We believe we have identified the root cause, and will address it in future work. Tezzaron intends to support the HEP community and, in future, to apply the technology to commercial applications like digital Xray and PET scanners. The Product Development Kit (PDK) planned as part of Phase II will allow less sophisticated users to exploit the newly developed sensor technology, permitting more widespread commercial adoption, especially by small and medium enterprises. Key words Silicon sensors, accelerator, silicon, detector, SPM. The project will develop a domestic commercial source of advanced silicon detectors for use in research applications such as particle accelerators and in medical and industrial devices such as PET scanners and digital Xray equipment.