3D Silicon Sensors - Large Area Production, QA and Development for the CERN ATLAS Experiment Pixel Sensor Upgrade

3D silicon sensors, where electrodes penetrate fully or partially through the silicon substrate, have been successfully fabricated in different processing facilities in Europe and the USA. The key to 3D fabrication is the use of plasma micromachining to etch narrow deep vertical openings which allow dopants to be diffused in and form the electrodes of the p-i-n junctions. Similar openings can be used at the sensor's edge to reduce the perimeter's dead area to be as narrow as 4 μm. Since 2009, four fabrication facilities of the 3D ATLAS R&D Collaboration started a joint effort aimed at one common design and compatible processing strategy for the production of 3D sensors for the LHC Upgrade and in particular for the ATLAS pixel Insertable B-Layer (IBL). In this project where the installation is aimed for 2013, a new layer will be inserted as close as 3.4 cm from the proton beams inside the existing pixel layers of the ATLAS experiment. The detector proximity to the interaction point will therefore require new radiation hard technologies for both sensors and front-end electronics. The latter, called FE-I4 is processed at IBM and is the biggest front end of its kind, with a surface area of about 4 cm^2. This paper will discuss some design aspects, and the different approaches taken by the facilities. Results from both the qualification runs and the current production runs for the IBL are also reported

Irradiated Silicon Detectors Operated At Cryogenic Temperature: The Lazarus Effect.

An increasing interest in the behaviour of silicon detectors at cryogenic temperatures has been awakened by the discovery of the so-called Lazarus effect, namely the recovery of Charge Collection Efficiency (CCE) by means of cryogenic cooling. We have measured the CCE of three single diodes previously irradiated with different neutron fluences. The current-voltage characteristic has been measured at 300 K and 77 K, showing that the low temperature operation considerably decreases the steady state current. This is also the case when forward voltage bias is applied, which then becomes a suitable option. At 77 K, in the case of samples irradiated with 510 14 n/cm 2 , the CCE is completely recovered. A third sample irradiated with 210 15 n/cm 2 shows a 60% CCE at 250 V forward bias. a also at Istituto di Cibernetica CNR, Arco Felice, Naples, Italy b also at ETL, Tsukuba, Japan c also at INFN Frascati, Italy Presented at the WSSM1 1999, Torino, Italy, to be published in the P..

Charge collection efficiency of an irradiated cryogenic double- p silicon detector

We present results on the measurement of the charge collection efficiency of a p(+) /n/p(+) silicon detector irradiated to 1 x 10(15) n/cm(2), Operated in the temperature range between 80 and 200 K. For comparison, measurements obtained with a standard silicon diode (p(+) /n/n(+)), irradiated to the same fluence, are also presented. Both detectors show a dramatic increase of the CCE when operated at temperatures around 130 K. The double-p detector shows a higher CCE regardless of the applied bias and temperature, besides being symmetric with respect to the polarity of the bias voltage

Final size planar edgeless silicon detectors for the TOTEM experiment

The TOTEM experiment will detect leading protons scattered in angles of microradians from the interaction point at the Large Hadron Collider. This will be achieved using detectors with a minimized dead area at the edge. The collaboration has developed an innovative structure at the detector edge reducing the conventional dead width to less than 100 microns, still using standard planar fabrication technology. In this new development, the current of the surface is decoupled from the sensitive volume current within a few tens of micrometers. The basic working principle is explained in this paper. Final size detectors have been produced using this approach. The current-voltage and current-temperature characteristics of the detectors were studied and the detectors were successfully tested in a coasting beam experiment