1. Overview of Activities at COMSATS Presented by: Team Leader: Hira KhanDr. Arshad S. Bhatti Sujjia Shaukat

2. Inner Tracking System (ITS) Present ITSUpgraded ITS SSD SDD SPD New ITS - 7 Layers Silicon Pixel Detector - Monolithic 12.5 G-pixel camera (~10 m 2 ) Current ITS - 6 Layers 3 different Silicon detectors 2 Beam pipe

3. Technologies for Silicon Pixel Detectors There are two technology concepts for silicon pixel detectors: Monolithic Active Pixel Sensor Hybrid Pixel Detector (MAPS) The sensor and the front end electronics is implemented on separate silicon chips The pixel detector and the read out electronics is implemented on same silicon chips 3

4. Explorer Series They are pixel prototypes developed at CERN as a part of the ongoing research and developments for the ALICE ITS Upgrade to optimize the diode layout, for the charge collection efficiency. The detector design motivation is to reduce the power density in the detection layers. The Explorer chip is divided into two sub-matrices containing pixels with two different pixel pitches. Each sub-matrix is divided into nine sectors, each having a different pixel variant. In Explorer-1, the width allocated for the collection electrode (the n-well diameter plus the spacing) is kept constant at 7.2 μm. Total number of pixels = 11700 pixels Total area of each sub-matrix = 3240000 μm 2 4 Spacing Diameter p-p- p-p- p+

5. Collection diode layouts 5

6. Objective To simulate MAPS collecting diodes of different geometric shapes and sizes and then observe their effects on the depletion region. To propose diode structures with different doping concentrations to enhance the sensing volume of the device and give better electrical performance. To study the effect of radiation on charge density in the diode. To study the effect of length of epitaxial layer on doping concentration of the device. 6

7. Simulation Software: Synopsys Sentaurus TCAD Industry-Standard Process and Device Simulators Technology Computer Aided Design (TCAD) Reduces technology development time and cost Supports fast prototyping, development, and optimization of semiconductor technologies with comprehensive physics- based process modeling capabilities Provides insight into advanced physical phenomena through self-consistent multidimensional modeling capabilities, improving device design, yield, and reliability Provides full-flow 3-D process and device simulation flows, with advanced structure generation, meshing and numeric. Start Sentaurus WorkBench Sentaurus Device Editor Sentaurus Device Define Variables End Simulation Error in Input command (Physics) and parameter file Error Run Simulation Error in Input command and grid file yes no View structure and graphs in Sentaurus Visual and INSPECT 7

8. 21μm 20μm Explorer-0 (Sector 4) Explorer-1 (Sector 1) Doping Profile and parameters of collection electrodes P-type Epitaxial layer, 1e12cm -3 P-type Substrate, 1e15cm -3 3μm3μm 20μm 21μm 2μm2μm 18μm N type doping, 1e18cm -3, N doped width: 3μm, N contact: 3μm P-contact: 20 μm 8 21μm 20μm Space, 3.375μm P-type Epitaxial layer, 1e12cm -3 P-type Substrate, 1e15cm -3 20μm 21μm N-type doping, 1e18cm -3, N doped width: 0.45μm, N-contact: 0.45 μm 2μm2μm 18μm P-type doping, 1e18cm -3 3μm3μm P-contact: 20 μm

9. Electric Field Region Depletion zone volume calculation 9

10. 10

11. Electrical characteristics measurements Current density of each sector of Explorer-1: 11

12. 1e15 cm -3 1e14 cm -3 1e13 cm -3 1e12 cm -3 Variation in doping profiles of MAPS: At constant anode doping, variation in P-type epi-layer doping profiles of MAPS: Sector 3 (Explorer-1) Epi-layer Doping: Optimization of Monolithic Active Pixel Sensors (MAPS) 12

13. Optimization of Monolithic Active Pixel Sensors (MAPS) Variation in doping profiles of MAPS: At constant epi-layer doping, variation in N-type anode doping profiles of MAPS: Sector 3 (Explorer-1) N Doping: 0.5e18 cm -3 2e18 cm -3 4e18 cm -3 6e18 cm -3 13

14. With increase of N doping, the reverse current increases.The increase in doping causes increase in depletion region. Current - Voltage measurements Anode doping concentration (cm -3 ) 14

15. Diamond shaped matrix of Sector 1 (Explorer-1) Variation in geometry of pixels in submatrix – Electric Field at reverse biased voltage of 7V (cross-sectional view) Optimization of Monolithic Active Pixel Sensors (MAPS) 15 21μm 40μm P-type Epitaxial layer, 1e12cm -3 P-type Substrate, 1e15cm -3 20μm 10μm P-type doping, 1e18cm -3 N type doping, 1e18cm -3, N doped width: 0.45μm, N contact: 0.45μm, Space N+ vs. P+, 3.375μm 11.26μm4.35μm 15.03μm7.44μm Depletion region

16. 0.69μm 4.5μm 6.94μm 11. 63μm Depletion region 20.97 μm 5.64μm This region can be utilized for VLSI implementation Optimized Diamond shaped matrix of Sector 1 (Explorer-1) – Electric Field at reverse biased voltage of 7V (cross-sectional view) Optimization of Monolithic Active Pixel Sensors (MAPS) 16 12μm 14μm 21μm 40μm N type doping, 1e18cm -3, N doped width: 0.45μm, N contact: 0.45μm, Space N+ vs. P+, 3.375μm P-type Epitaxial layer, 1e12cm -3 P-type Substrate, 1e15cm -3 P-type doping, 1e18cm -3

17. Available region for front-end complex CMOS circuitry Optimized Diamond shaped matrix of Sector 1 (Explorer-1) Optimization of Monolithic Active Pixel Sensors (MAPS) 17

18. 16μm P-type doping, 1e18cm -3 16μm N type doping, 1e18cm -3, N doped width: 2 μm, N contact: 2 μm, Space N+ vs. P+, 2.6 μm 18.71μm 9.59μm 18.71μm 6.13μm 6.86μm 6.13μm 2.36μm 28.34 μm Depletion Region of optimized Sector 3 Space for VLSI Implementation Optimized Diamond shaped matrix of Sector 3 (Explorer-1) – Electric Field at reverse biased voltage of 7V (cross-sectional view) Optimization of Monolithic Active Pixel Sensors (MAPS) 18

19. P type doping, 1e18cm -3 P-type Epitaxial layer, 1e12cm -3 P-type Substrate, 1e15cm -3 16μm N type doping, 1e18cm -3, N doped width: 2 μm, N contact: 2 μm, Space N+ vs. P+, 2.6 μm 16μm Optimized Hexagonal shaped matrix of Sector 3 (Explorer-1) – Electric Field at reverse biased voltage of 7V (cross-sectional view) Optimization of Monolithic Active Pixel Sensors (MAPS) 19 Depletion region of optimized hexagonal shaped Sector 3 Space for VLSI Implementation 18.75 μm 9.75 μm 6.17 μm 6.93 μm 6.17 μm 1.87 μm 28.07 μm

20. 15.7um 16.5um 13.26um 10.37um 10.51um 1.45um 45.14um 15.72um Extension of optimized Hexagonal shaped matrix of Sector 3 (Explorer-1) – Electric Field at reverse biased voltage of 7V (cross-sectional view) Optimization of Monolithic Active Pixel Sensors (MAPS) 20

21. Current - Voltage measurements Reversed current was minimized in case of extended hexagonal shaped matrix. 21

22. Effect of radiation on Charge Density of the device

23. Charge Density of the device when no radiation was passed (at -2V) 23

24. Applying radiation effects in the device 24

25. Irradiating the device diagonally 25

26. Irradiating the device diagonally 26

27. Charge Density of the irradiated device (at - 2V) 27

28. Charge Density of the device when no radiation was passed (at -3V) 28

29. Charge Density of the irradiated device (at - 3V) 29

30. I-V curve of radiated and non-radiated structure 30

31. Charge Density of the device when no radiation was passed (at -7V) 31

32. Charge Density of the irradiated device (at - 7V) 32

33. I-V graphs of the structure at different trap densities 33

34. Effect of different Epitaxial layer height on doping concentration of Explorer pixel sensor (ALICE-ITS) using TCAD Sentaurus Process

35. Flowchart of Epitaxial growth using Sentaurus Process Silicon Epitaxial layer growth on low resistive P-type Silicon substrate P-type doping of Epitaxial layer Annealing at 1100 °C for activation of Boron Dopants Etching for Step- like structure 35

36. Epitaxy dimension of different lengths 36

37. Doping profile and dimensions of Epilayer 37

38. Effect of Constant Doping of Boron on different length Epitaxial layer 38

39. Dimension of Step-like Structure of Graded Boron Epitaxial growth 39

40. Boron Concentration for Step-like structure 40

41. All the diode designs for Explorer-0 and Explorer-1 chip were simulated using Synopsys Sentaurus TCAD tools: SDE, SDEVICE and SVISUAL. The depletion regions volumes of sector 3 and 9 were calculated to be maximum of 517.81 μm -3 and 497.85 μm -3 respectively. In case of varying the doping profiles of the device, maximum depletion region volume was obtained for P doping of 1e12cm -3 and N doping of 6e18cm -3 as according to following: It was found that by shifting the anodes at the center in form of Extended Hexagonal shape enhance the depletion region volume upto 35%. This geometry not only enhance the depletion zone volume but also create more space for complex VLSI implementation. An increase in the reverse current was observed when the device was irradiated with a Gaussian profile at trap density of 1e14cm -3. Conclusion 41

42. To calculate capture efficiency of the irradiated device. To study the effect of radiation when traps are outside the sensitive region of the device. 42 Future Work To apply voltages at etched surfaces To calculate resistivity of structure at different points

43. ALICE ITS Readout Electronics Inner Barrel Emulator card Group Members: Team Leader: Hira Ilyas Dr. Arshad S. Bhatti Madiha Tajwar Jibran Ahmed Raise Akram (carrier board)

44. Inner Barrel Emulator card Each spartan6 will emulate a single chip. Each spartan will send data 1.2Gbps on diff line. Readout prototype board will receive data on 9 differential lines from 9 spartans. Firmware is written for single spartan and it will copy in all nine. 8 bit Data, master clock and control lines will be driven by readout prototype board (plus PC through USB controller)

45. Architecture of IOBE Board

46. Total Signals Set-up for single Chip (SP6) SPARTAN 6 Power USB JTAG Platform flash User clockGTP clock High speed serial data Controls SPI header

47. Hardware Requirement: Spartan-6 Software Requirements: Vivado Spartan-6, GTP Transceivers Wizard System Requirements

48. Spartan-6, GTP Transceivers Wizard Ref_clk=125MHz TX Line Rate=1.25 Gbps RX Line = 2.5 Gbps Data Path Width= 16 bits

49. Thank you 49