Silicon pixel detectors and electronics for hybrid photon

Silicon pixel detectors and electronics for hybrid photon detectors Ken Wyllie, CERN on behalf of the LHCb pixel HPD group OUTLINE § Principle and requirements § LHCBPIX 1: General chip description § Pixel cell description § Silicon sensor § Electronics performance § Bump-bonding & packaging § Integration in hybrid photon detector § Conclusion and future plans 1

Principle of the hybrid photon detector (HPD) Designed to meet specs of LHCb Ring-Imaging Cherenkov Detector: § § § 2 Low noise – pattern recognition Low detection threshold ~ 2000 e 25 ns time precision (LHC) 2. 5 mm x 2. 5 mm channel size (focus x 5) 8% maximum time occupancy Compatible with HPD manufacturing Firenze RD 03, 30 th September 2003

§ Commercial 0. 25 um CMOS process § 6 metal layers § Radiation-tolerant layout § 13 million transistors § 1. 8 W total power (40 MHz clk, 1 MHz trig) § Current-starved logic § 2 nd generation of ALICE 1 LHCB chip § see talk by G Stefanini 21 mm LHCBPIX 1 General Chip Description DACs 16 mm 3 Firenze RD 03, 30 th September 2003

Pixel Cell Description One super-pixel (500 um * 500 um) = 8 mini-pixels (62. 5 um * 500 um) 62. 5 um 500 um 4 Firenze RD 03, 30 th September 2003

Silicon Sensor Optimised for photoelectron detection (Canberra, Belgium) Diode side: p-on-n pixel diodes Ohmic side: X-section 5 Firenze RD 03, 30 th September 2003

Electronics performance 1 Analog & digital performance meet LHC speed requirements Shaper output 25 ns 100 ns shaper output 5000 e- input 6 Firenze RD 03, 30 th September 2003

Electronics performance 2 Using calibration test pulse Mean ~ 970 e. RMS ~ 90 e- Mean ~ 130 e- (Without individual threshold adjustment) 7 Firenze RD 03, 30 th September 2003

Bump-bonding VTT, Finland: bump-bonding recipe using solder with high melting-point. Compatible with: § high temp curing of glue used for packaging § high temp processing of HPD (bake-out) 25 um 8 Firenze RD 03, 30 th September 2003

Packaging of chip+sensor assembly Custom ceramic PGA carrier Test with Sr 90 beta-source Si sensor Si bias connection Wire-bonds to chip Pin grid array 9 Firenze RD 03, 30 th September 2003

Encapsulation in HPD From DEP, Holland 10 Firenze RD 03, 30 th September 2003

… and finally Cherenkov rings! LHCb UK RICH 1 prototype Cherenkov rings (air radiator) One trigger 11 Accumulated triggers Firenze RD 03, 30 th September 2003

Conclusions and Future Plans § Silicon pixel sensor & electronics chip designed for HPD application § Electrical requirements of chip fulfilled § New bump-bonding process used § Packaged & encapsulated in HPD => Cherenkov photon detection § Pre-production run of chip wafers tested => more HPDs § Ageing tests of assemblies & HPDs underway § Measure aerogel Cherenkov rings 12 Firenze RD 03, 30 th September 2003