SOIPD 2009 SOIPD KEK-LBNL-Padova collaboration

SOIPD 2009 Silicon On Insulator (SOI) detectors SOI-2 (2008) 0.20um OKI FD-SOI technology 128  172 digital pixels (20  20 um 2 ) 40  172 analog pixels (20  20 um 2 ) Optimized for low leakage current Currently under test SOI-2-IMAGER (2009) 0.20um OKI FD-SOI technology 256  256 analog pixels (13.75  um 2 ) 4 analog outputs 5mm chip, 3.2mm active Just delivered ● CMOS electronics implanted on a thin silicon layer on top of a buried oxide (BOX): ensures full dielectric isolation, small active volume and low junction capacitance ● Radiation sensors can be built by using a high resistivity substrate and providing a technology to interconnect the substrate through the BOX SOI-1 (2007) 0.15um OKI FD-SOI technology 160  50 digital pixels (10  10 um 2 ) 160  100 analog pixels (10  10 um 2 ) MIPs detection First radiation damage tests

SOIPD 2009 SOI-1 Tests on Analog and Digital Pixels Tests with a 1060nm IR laser (analog section) IR laser spot: 20um; analog section tested for different V d values; signal pulse height measured in a 5×5 matrix, centered around the laser spot centre; signal increases as √V d signal increases as √V d as expected (increasing depletion region) until V d ≃ 9 V, where it saturates; it decreases for V d ≥ 15 (transistor back- gating). IR laser spot: 5um; pixel matrix scanned in 1um steps; position reconstructed by the center of gravity of the reconstructed cluster charge; resolution calculated by the spread of the reconstructed cluster position for events taken at each point in the scan and for different S/N values; resolution scaled as the inverse of S/N resolution scaled as the inverse of S/N, as expected (continuous line). Cluster pulse height Single Point Resolution Tests with High Energy Particle Beam (digital section) chip tested on the 1.35 GeV electron beam-line at the Advanced Light Source (ALS); hit multiplicity observed in the digital pixels for events taken with and without beam a clear excess of hits can be seen in the presence of beam

SOIPD 2009 SOI-1 Radiation Hardness Tests 30 MeV protons Irradiation performed at the BASE Facility of the LBNL 88- inch Cyclotron with 30 MeV protons on single transistors; study of the variation in the threshold voltage for the nMOS test transistor as a function of the proton fluence; irradiation performed up to a total dose of ≃ 600 kRad. the total threshold variation is indeed significant (  100 mV) also for a low substrate bias (i.e. V d = 1 V). The effect is much larger than what would be expected at such doses from radiation damage in the transistor thin gate oxide and is clearly due to charge build-up in the thick buried oxide similar results are obtained for the pMOSFET characteristics. An initial substrate voltage Vd = 5 V was used, but after a fluence of about 1×10 12 p/cm 2 the transistor characteristics could not be properly measured, and a reduced substrate bias of Vd = 1 V needed to be apply in order to recover the transistor characteristics MeV neutrons Irradiation performed at the LBNL 88-inch Cyclotron with 1-14 MeV neutrons on the analog pixel matrix; study of the sensor noise before and after irradiation as a function of the depletion voltage at room temperature; irradiation performed up to a total fluence of 1.2×10 13 n/cm 2 ; a noise increase was observed after irradiation, varying from +25% for V d = 5 V, to +52% for V d = 20 V. This is interpreted as due to radiation-induced increase of leakage current in the sensor substrate Ionizing radiation Non Ionizing radiation V d = 10V

SOIPD 2009 SOI-1 Tests & Simulations I ds vs V gs curve is drawn for different values of substrate bias Threshold voltage is extracted from maximum g m in simulations (left plot) Same procedure is used on experimental data (right plot) TCAD simulation I ds vs V gs curve Experimental data Backgating is much less effective in simulations Hypothesis: BOX = large and extended gate ! are there some 3D effects (e.g. currents flowing on the side)? V threshold extraction

SOIPD 2009 Backgating reduction PSUB ring surrounding the transistor floating PSUB ring surrounding the transistor grounded Experimental Data ● The substrate voltage acts as a back-gate, changing the transistor threshold until making it unable to work for voltages > 16V. ● The effectiveness of placing p+ implants close to the transistor to mitigate the problem has been investigated, both with simulation and with experimental measurements. TCAD Simulation PSUB grounded actually limits the backgating effect!

SOIPD 2009 SOI-2 Tests X-ray irradiation on 0.20um technology transistors up to a total dose of 56 krad (SiO 2 ) with V back = 5V during irradiation; PMOS transistors show no increment on leakage current; leakage current for NMOS transistors is still at acceptable levels. ● Radiation Damage Tests ● Test on the detector Digital pixels 90 Sr, V dep = 35 V Analog pixels tested at LBNL ALS with 1.5 GeV e - : S/N~15-20 and ENC~20-30 e - up to 50 MHz clock frequency and V dep =5 V (stronger effect of back-gating w.r.t  m process) Digital pixels operable up to V dep =35 V, proof of functionality achieved with 90 Sr source Analog pixels 1.5 GeV e -, V dep = 2 V

SOIPD 2009 SOI-2 Imager

SOIPD D detector

SOIPD 2009 Attività 2010 Caratterizzazione SOI imager come rivelatore particelle al minimo Caratterizzazione SOI imager back-illuminated come rivelatore di fotoni Studio back-gating via IEEM Studio 3D detector Seconda produzione SOI-3D

SOIPD 2009 Attività gruppo e servizi Progetto, disegno, test nuove mezzanineProgetto, disegno, test nuove mezzanine Test sensoriTest sensori Test beamTest beam Misura radiation hardness con IEEMMisura radiation hardness con IEEM Messa a punto IEEMMessa a punto IEEM 6 m/u 6 m/u Progettazione e test nuove mezzanine 3 m/u + 1 m/u CADProgettazione e test nuove mezzanine 3 m/u + 1 m/u CAD Test dispositivi 5 m/uTest dispositivi 5 m/u Piccoli interventi OM 2 m/uPiccoli interventi OM 2 m/u

SOIPD 2009 Bisello RN 30 Candelori 30 Giubilato 30 Mattiazzo 30 Nigro 100 Silvestrin 100 Wyss 30 Gerardin 70 Mint 2 ke Mest 4 missioni LBL 1 missione KEK 1 conferenza 1 m/u test beam 15 Cons. qp produzione mat. test lab. mezzanine 40