Abstract
The CMS collaboration is currently conducting a campaign to identify radiation-hard materials for an upgrade of the CMS tracker. This upgrade is needed to be able to cope with the higher radiation background of the future HL-LHC; additionally the performance of the current tracker will be significantly degraded at the time of the upgrade, requiring a replacement. Several different test structures (TSs) and sensors have been designed for a 6 in. wafer layout. These wafers were produced by an industrial supplier (Hamamatsu Photonics K.K.) and differ by their bulk material (Float Zone, Magnetic Czochralski and CVD-Epi), thickness (from 50μm to 320μm) and N–P type doping. These TSs consist of different microelectronic devices including diodes, resistors or MOS structures. They enable the extraction of parameters which are not accessible in a silicon detector and allow the assessment of the quality of the sensors produced on the same wafer. The TSs have been irradiated with protons and neutrons to emulate the radiation damage caused by the particle fluence inside the future CMS tracker after 10 years of operation. This contribution will present measurements of non-irradiated and irradiated test structures at different fluences. The changes of the properties of the microelectronic devices will be discussed as well as the design of the TSs.
Highlights
The interstrip capacitance is shown in figure 9
One can see a major increase after the first irradiation step
These first irradiation results show that as expected some parameters change with irradiation while others remain mostly stable
Summary
The current Compact Muon Solenoid (CMS) tracker at the Large Hadron Collider (LHC) has to withstand high levels of radiation due to the high luminosity of the LHC of up to 1034 cm-2s-1. This harsh radiation environment leads to a degradation of the silicon tracking sensor performance. In order to meet these requirements demanded in the future, the HPK2-campaign aims to define the future tracker sensor baseline. Each of these structures consists of sub-structures They are used to investigate different aspects of the future tracker baseline [2], e.g. the choice of wafer material or sensor layouts. This article focuses on the two test-structures (TSs) which are highlighted with red rectangles in figure 1
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