1. 8/22/01Marina Artuso - Pixel Sensor Meeting - Aug 2001 1 Sensor R&D at Syracuse University Marina Artuso Chaouki Boulahouache Brian Gantz Paul Gelling JC Wang

2. 8/22/01Marina Artuso - Pixel Sensor Meeting - Aug 2001 2 Outline Review of the Syracuse R&D activities and facilities –Simulation work –Sensor characterization – wafer measurements –Sensor characterization – measurements on sensors bump bonded to readout electronics Planned upgrades Some thoughts on sensor R&D strategy

3. 8/22/01Marina Artuso - Pixel Sensor Meeting - Aug 2001 3 Simulation activities Standalone program to model charge collection properties of generic pixel sensor & front end electronics  definition of cell size & useful input for the front end electronics requirement document (JC Wang) Optimization of the geometry of the individual pixel cell and fine tuning of the sensor technology requires a more complex simulation tool (ISE-TCAD) (Chaouki Boulahouache) P-spice simulation of fpix2 (starting) to understand the details of the sensor formation and capacitive coupling between channels. (Brian Gantz)

4. 8/22/01Marina Artuso - Pixel Sensor Meeting - Aug 2001 4 Why undertake the sensor simulation effort? Lot of progress has been made to identify silicon pixel detector technologies suitable for high radiation environments The preferred technology is quite complex and involves several processing steps. Understanding the implication of the various process parameters will enable us to perform a choice that will optimize yields and radiation resistance We are using a professional CAD program (ISE- TCAD) to develop a deeper understanding of the various steps in this process

5. 8/22/01Marina Artuso - Pixel Sensor Meeting - Aug 2001 5 ISE-TCAD fundamentals What can be studied: –Electric field profile on the sensor (before and after irradiation)  identification of the high field regions that may lead to break-down. –Equivalent capacitance of the chosen geometry  potential effects on intrinsic noise of the pixel cell –Time development of the signal in the electrodes in the cluster  refined modeling of the charge sharing including time dependent effects

6. 8/22/01Marina Artuso - Pixel Sensor Meeting - Aug 2001 6 Simulation tools overview Algorithms explored

7. 8/22/01Marina Artuso - Pixel Sensor Meeting - Aug 2001 7 Steps in the electrostatic single cell simulation Sensor description (Detailed description of the fabrication steps) Mesh generation (define a grid Of space-points to do the calculation) Diffusion and recombination + Solution of Poisson equation

8. 8/22/01Marina Artuso - Pixel Sensor Meeting - Aug 2001 8 Lateral Field distribution for P-stop and P-spray before Irradiation… P-stopP-spray Lateral Field Distribution from the edge of the n+ strips to the middle of the p+ implant region. Distance(  m) Pixel Boundary

9. 8/22/01Marina Artuso - Pixel Sensor Meeting - Aug 2001 9 A typical example of p-stop and p-spray sensors for ATLAS DESIGN Max-Lateral Field in(kV/cm) Our ResultAtlas’s paper result P-stopP-sprayP-stopP-spray Unirradiated134340120380 Low Fluence N ox =1.5*10 12 295225140172 High Fluence (Irradiated case) 34954480192

10. 8/22/01Marina Artuso - Pixel Sensor Meeting - Aug 2001 10 Experimental activities at SU The pixel sensor lab (clean room) is now equipped to perform wafer-level measurements of: –I-V response –C-V response Planned upgrade: –Laser test-stand to measure signal properties of instrumented sensors –Thermally controlled chuck to test radiation damage devices at desired temperature (?? If funds become available)

11. 8/22/01Marina Artuso - Pixel Sensor Meeting - Aug 2001 11 First data from c-v measurement station

12. 8/22/01Marina Artuso - Pixel Sensor Meeting - Aug 2001 12 Experimental activities at SU - the electronics lab VME based test stand to perform FPIX0 and FPIX1 instrumented sensor characterization PCI test stand compatible with new PIXEL test stand under development Will be adapted to RICH test stand for HPD characterization and future test beam

13. 8/22/01Marina Artuso - Pixel Sensor Meeting - Aug 2001 13 The SU pixel test program We want to be a full partner with Fermilab in the initial sensor design and characterization Now: –Define measurements on a set of chosen sensors and test structure to cross-calibrate test benches and optimize characterization techniques –Interplay between measurement and simulation to achieve full understanding of sensor properties 2nd step: define quality control criteria & measurements that can be performed at SU

14. 8/22/01Marina Artuso - Pixel Sensor Meeting - Aug 2001 14 SENSOR DEVELOPMENT STAGES 1st test beam has proven that the needed resolution can be achieved with a variety of sensors A variety of p-stop and p-spray sensors are now in our hand to refine the choice on the basis of performance in the beam, reliability and expected yields, radiation resilience. Next important submission should include one or two more promising solutions (determined with the measurements and studies proposed before) and a variety of test structures to diagnose possible failure modes: –Vulnerability to breakdown –Depletion voltage –Factors affecting inter-pixel capacitance and resistance

15. 8/22/01Marina Artuso - Pixel Sensor Meeting - Aug 2001 15 Additional goals Identify 2 or 3 vendors capable to produce our sensors with good yields Develop a good understanding of their process and the parameters that can be optimized for our needs Define the quality control  production stage

16. 8/22/01Marina Artuso - Pixel Sensor Meeting - Aug 2001 16 Conclusions We have taken several steps to contribute to the sensor design and testing for the BTeV pixel detector We have gained good experience with the various front end devices of the FPIXn family We consider the next submission to foundry a key milestone in our project and we would like to be active participants in this effort.