Pre-production results from ATLAS ITk Strip Sensors Quality Assurance Testchip

Abstract

The production of strip sensors within the framework of the ATLAS Inner Tracker (ITk) development is a process which requires continuous evaluation during the full production period (about 4 years). Such an evaluation is divided into two different parts: Quality Control (QC), which focuses on the final product (the actual sensors) and tries to identify possible defects once the fabrication is completed, and Quality Assurance (QA), which aims to prevent deviations in the manufacturing process and uses specifically-designed test structures. The initial sensor pre-production consists of 5% (1041 sensors) of the total number of sensors expected during production. As part of pre-production, the collaboration has measured key parameters from miniature strip sensors (minis), monitor diodes (MD8), and the ATLAS Testchip, before and after irradiation. In this contribution we focus on the analysis of the results of the MD8 and the Testchip. All parameters have been obtained from the test structures (MD8, bias resistors, interdigitated structures, field oxide capacitors, coupling capacitors, punch-through protection structures and cross-bridge resistors) measured at the different test sites (KEK/Tsukuba, Birmingham, Toronto, Ljubljana, Valencia, Carleton, Prague, CNM-Barcelona). The results are compared to predefined pre- and post-irradiation specifications for each tested parameter.

Specifications and pre-production of n+-in-p large-format strip sensors fabricated in 6-inch silicon wafers, ATLAS18, for the Inner Tracker of the ATLAS Detector for High-Luminosity Large Hadron Collider

“…The main sensors and the halfmoons were distributed to the testing clusters to be used for establishing acceptance procedures and evaluating the performance of the main sensors (Quality Control (QC)) [11]. The QA pieces were distributed to the testing sites of the quality assurance program [12,13]. The quantities of the Pre-production wafers are summarized in Table 7, with their breakdown per sensor type and the distribution to the testing clusters.…”

Establishing the Quality Assurance programme for the strip sensor production of the ATLAS tracker upgrade including irradiation with neutrons, photons and protons to HL-LHC fluences

“…It consists of a series of 𝑛 + implants of which every odd implant is connected at one side, and every even strip at the other so the total strip length is equal to that in the main sensors. The strips are surrounded by a bias ring, to which they are not connected and a guard ring [12]. There are three interdigitated structures on each test chip with different strip lengths and angles corresponding to main sensors for different parts of the strip detector.…”