Front-End Performance and Charge Collection Properties of Heavily Irradiated DNW MAPS

Dipt. di Elettron., Univ. degli Studi di Pavia, Pavia, Italy
IEEE Transactions on Nuclear Science (Impact Factor: 1.46). 09/2010; DOI: 10.1109/TNS.2009.2039003
Source: IEEE Xplore

ABSTRACT Deep N-well (DNW) CMOS monolithic active pixel sensors (MAPS) fabricated in a 130 nm technology have been exposed to γ-rays up to an integrated dose of about 10 Mrad and subjected to a 100 °C/168 h annealing cycle. Device tolerance to total ionizing dose has been evaluated by monitoring the change in charge sensitivity, noise and charge collection properties after each step of the irradiation and annealing campaign. Damage mechanisms and their relation to front-end architecture and sensor features are thoroughly discussed by comparing the response to ionizing radiation of different test structures and based on radiation induced degradation models in single MOS transistors.

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    ABSTRACT: Total ionizing dose effects are studied in 130-nm transistors and pixel sensors in a vertically integrated two-layer CMOS technology, evaluating the possible impact of 3D integration on radiation tolerance and damage mechanisms. Measurements of static characteristics and noise voltage spectra before and after exposure to high total ionizing doses demonstrate that the analog performance of transistors as well as their radiation hardness are not degraded by mechanical and thermal stresses occurring during the fabrication of the 3D chips. The paper also presents irradiation results on 3D CMOS pixel sensors with a sparsified readout architecture. After exposure to ionizing radiation, these devices behave in a very similar way as analogous counterparts in a standard 2D 130-nm process, confirming that performance advantages associated with 3D integration are not impaired by an enhanced radiation sensitivity.
    IEEE Transactions on Nuclear Science 12/2013; 60(6):4526-4532. DOI:10.1109/TNS.2013.2286676 · 1.46 Impact Factor
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    ABSTRACT: This work is concerned with the characterization of deep n-well (DNW) CMOS monolithic active pixel sensors (MAPS) fabricated in a 130 nm homogeneous vertically integrated technology. An evaluation of the 3D MAPS device performance, designed for a possible future upgrade of the SuperB-Layer0, is provided through a complete characterization of the prototypes, including tests with infrared (IR) laser, 55Fe and 90Sr sources. The radiation hardness study of the technology will also be presented together with its impact on 3D DNW MAPS performance.
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    ABSTRACT: A model, approximating minority carrier diffusion with a discrete random walk and accounting for radiation induced reduction of minority carrier lifetime, is proposed to predict the effects of neutron irradiation on the charge collection properties of monolithic active pixel sensors (MAPS) in CMOS technology. The model has been implemented in a Monte Carlo code to simulate MAPS operation in minimum ionizing particle detection systems. For the purpose of validating it, the results from the characterization of monolithic sensors irradiated up to an integrated fluence of 1014 1- MeV-neutron equivalent/cm2 have been compared with the outcomes of the Monte Carlo simulations. The monolithic sensors taken into consideration for the model validation are based on two different CMOS processes, one featuring a triple well option, the other one featuring a quadruple well structure and a standard (10 Ω·cm) or high (1 kΩ·cm) resistivity epitaxial layer. Simulation results are shown to be in good agreement with experimental data. The consistency between the model and the measurement results seems to confirm that radiation induced increase in the recombination rate is the main source of charge collection degradation in neutron-irradiated MAPS.
    IEEE Transactions on Nuclear Science 08/2013; 60(4):2574-2582. DOI:10.1109/TNS.2013.2248383 · 1.46 Impact Factor

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