Universit di Pavia Dipartimento di Elettronica I27100 Pavia

Università di Pavia Dipartimento di Elettronica, I-27100 Pavia, Italy 1 MAPS in 130 nm triple well CMOS technology for HEP applications INFN Sezione di Pavia I-27100 Pavia, Italy 2 Enrico Pozzati 1, 2, Massimo Manghisoni 2, 3, Lodovico Ratti 1, 2, Università di Bergamo Dipartimento di Ingegneria Industriale, I-24044 Dalmine (BG), Italy 3 Valerio Re 2, 3, Valeria Speziali 1, 2, Gianluca Traversi 2, 3 Introduction In this work deep N-well CMOS monolithic active pixel sensors (DNW-MAPS) are presented as an alternative approach to signal processing in pixellated detectors for high energy physics experiments. Based on different resolution constraints, some prototype MAPS, suitable for applications requiring different pitch, have been developed and fabricated in 130 nm triple well CMOS technologies. This work presents experimental results from the characterization of some test structures together with TCAD and Monte Carlo simulations intended to study the device properties in terms of charge diffusion and charge sharing among pixels. Deep N-well pixel sensor concept Apsel 2 laser source tests A deep junction N-well is used as the collecting electrode. The impact of front-end electronics on the pixel fill-factor can be limited by placing the NMOS devices belonging to the processor analog section inside the deep N -well structure. Efficiency loss due to the presence of Ntype diffusions housing P-type transistors might not be significant whether the deep N-well is comparatively larger. Prototype chips A low power In. Ga. As/Ga. Al. As/Ga. As laser source has been employed for experimental characterization of the Apsel 2 T chip 3× 3 matrix (λ = 1060 nm). The chip has been back-illuminated in order to avoid reflection from the die surface. Electrical pulses with an energy close to 200 f. J are required to emulate a MIP at the die surface (substrate thickness = 254 µm). (*) Matrix scan tests fearure 961 laser position points with a 5 µm step along both X and Y directions. Apsel family chips Charge collected by the 3× 3 matrix as a function of the laser spot position. Readout chain includes charge preamplifier, shaping stage, threshold discriminator and latch. Charge sensitivity [m. V/f. C] Peaking time can be programmed to assume one of the following values: 0. 5 µs, 1 µs, 2 µs. PIXEL The pitch is about 50 µm. Central pixel equipped with a 60 f. F injection capacitor SDR 0 chip Readout chain includes charge preamplifier, threshold discriminator and latch. The pitch is about 25 µm and is suitable for applications at the International Linear Collider experiments. Signal processing at pixel level include sparsified data readout. Charge collected by the central pixel in the 3× 3 matrix as a function of the laser spot position. 1_1 614 1_2 610 1_3 540 2_1 573 2_2 576 2_3 500 3_1 565 3_2 600 3_3 534 Apsel 2 -geometry physical simulation SDR 0 -geometry physical simulation Monte Carlo simulation assumptions 80 electrons for each micron are generated uniformly along a linear track normal to the device surface. Gaussian distribution in the plane orthogonal to the track with σ=0. 5 µm. Simulated volume is 230× 80 µm 3. Electron lifetime has been taken into account (9. 2 µs @ NA = 1015 cm-3 ). (**) TCAD simulated device. 36 collision points have been considered with a 5 µm step for both X and Y axes. a) b) Charge collected by the central pixel in the 3× 3 SDR 0 matrix according to TCAD simulations (a) and Monte Carlo simulations (b). Monte Carlo simulation results. Charge collected by the 3× 3 matrix as a function of the incident particle position. Monte Carlo TCAD Charge collected by the central pixel 1011 1060 Charge collected by the 3× 3 matrix 1619 Matrix loss (%) with respect to the max value (**) 48 Laser Monte Carlo Charge collected by the central pixel 1398 1512 Charge collected by the 3× 3 matrix 2283 2343 31 31 Matrix loss (%) with respect to the max value (*) Comparison between experimental and simulated results for the Apsel 2 MAPS. (*) Monte Carlo simulation results. Charge collected by the Apsel 3× 3 matrix is displayed as a function of the position of the MIP collision point. Conclusions 1566 A laser source has been employed to characterize the Apsel geometry in terms of charge diffusion and charge sharing among pixels. 49 A Monte Carlo code have been developed to simulate random walk of minority carriers in an undepleted detector substrate. Comparison between Monte Carlo and TCAD simulation results for the SDR 0 MAPS. Experimental results on the 3× 3 matrix of the Apsel 2 T chip can be reproduced in Monte Carlo simulations. A good agreement was found between TCAD and Monte Carlo results in the SDR 0 geometry simulation. Further investigation on the MAPS properties will be performed in the next months with the experimental characterization of the SDR 0 prototype chip.