AC-coupled n-in-p pixel detectors on MCz silicon with atomic layer deposition (ALD) grown thin film

Abstract

We report initial characterization of our novel sensor process solutions with AC-coupled n+/p−/p+ pixel detectors made on 150 mm diameter p-type Magnetic Czochralski silicon (MCz-Si) wafers. The pixels were segmented in a 52 × 80 dual column array and designed to be AC capacitive coupled. The resistive coupling between pixels, allowing quality assurance probing prior the flip chip bonding, was realized with thin film metal-nitride resistors fabricated by sputtering deposition. This approach allows us to omit punch-through resistor structures, which reduces the overall process complexity. Moreover, our previous studies have emphasized that applying ALD Aluminum Oxide (Al2O3) field insulator and passivation layer results in negative net oxide charge and thus additional p-spray or p-stop surface current termination structures are not necessary. Our focused application is a radiation-hard ALD AC-coupled pixel detector to be used in future particle physics experiments, such as the High-Luminosity Large Hadron Collider (HL-LHC), as well as photon counting applications. The pixel detectors were tested at Helsinki Institute of Physics (HIP) Detector laboratory and Ruđer Bošković Institute (RBI). We show measurement data of pixel detectors and other test structures. For the TiN resistors surrounding pixels, the resistance values were measured to be about 15kΩ. Data of electrical properties, full depletion voltage and leakage current are shown as well. Our Transient Current Technique (TCT) measurements indicated clear pixel segmentation with excellent homogeneity. For further study, AC-coupled sensors were hybridized to PSI46dig read out chips (ROC) by flip-chip interconnection technique and tested with a radioactive source.