1. Eija Tuominen Siena 22.10.2002 TEST BEAM RESULTS OF A LARGE AREA STRIP DETECTOR MADE ON HIGH RESISTIVITY CZOCHRALSKI SILICON Helsinki Institute of Physics, CERN/EP, Switzerland Microelectronics Centre, Helsinki University of Technology, Finland Okmetic Ltd., Finland Ioffe PTI, Russia Brookhaven National Laboratory, USA Univesity of Hamburg, Germany Accelerator Laboratory, University of Jyväskylä, Finland CERN RD39 & RD50

2. Eija Tuominen Siena 22.10.2002 OUTLINE 1.Czochralski grown silicon 2.Wafer characteristics 3.Device processing 4.Test beam results 5.Conclusions

3. Eija Tuominen Siena 22.10.2002 WHY CZ-Si AS A DETECTOR SUBSTRATE 1.Radiation hardness * Oxygen increases the radiation hardness of silicon detectors * Cz-Si intrinsically contains oxygen, 10 17 -10 18 cm -3 2.Cost-effectiveness * Cz-Si wafers are cheaper than traditional Fz-Si wafers * Large area wafers available -> possibility for large detectors -> cost-effectiveness for front-end electronics, interconnection and module assembly

4. Eija Tuominen Siena 22.10.2002 WHY CZ-Si AS A DETECTOR SUBSTRATE II 3.High oxygen concentration allows some additional benefits * Depletion voltage of detectors can be tailored by adjusting a) oxygen concentration in the bulk b) thermal history of wafers (Thermal Donor killing) WHY NOT BEFORE? * No demand for high resistivity Cz-Si -> No availability * Price for custom specified ingot 15,000 € - 20,000 € * Now RF-IC industry shows interest on high resistivity Cz-Si (=lower substrate losses of RF-signal) * Cz-Si of resistivity  5k  cm reported: T.Abe and W.Qu, High resistivity CZ silicon for RF applications substituting GaAs”, Electrochemical Society Proc. Vol. 2000-17 (2000) 491-500.

5. Eija Tuominen Siena 22.10.2002 WAFER CHARACTERISTICS * 4” single side polished * nominal resistivity 900  cm * thickness 380 um * orientation * oxygen concentration <10 ppma * grown by magnetic Czochralski method (MCZ) -> oxygen concentration is ”low” and well controlled

6. Eija Tuominen Siena 22.10.2002 DEVICE PROCESSING Simple fabrication process: 4 Lithographies 2 Ion implantations 2 Thermal dry oxidations 3 Sputter metal depositions Large area detectors: A=32.5 cm 2 I L (900 V) = 3 uA V fd = 420 V (380 um)

7. Eija Tuominen Siena 22.10.2002 HELSINKI SILICON BEAM TELESCOPE (hardware) * Situated at the CERN H2 beam * eight silicon strip detectors * front-end electronics with VA1 chips

8. Eija Tuominen Siena 22.10.2002 HELSINKI SILICON BEAM TELESCOPE (software) * Analog to Digital Converter with programmable DSP * PC based data acquisition with on-line monitoring * Separate off-line analysis

9. Eija Tuominen Siena 22.10.2002 BEAM TEST RESULTS Resolution  10 um Efficiency  95 % Signal/Noise  10

10. Eija Tuominen Siena 22.10.2002 CONCLUSIONS Full size (32.5 cm 2 ) Cz-Si strip detectors were processed Electrical performance: Depletion voltage 420V Leakage current  3  A@900V No breakdown under 900V Detector performance: Resolution  10 um Efficiency  95 % S/N  10 Radiation hardness: being tested by gamma, proton and neutron beams