MALTA Investigator I-V Measurements Shiyu Wang (Boston University), Enrico Schioppa (CERN), Carlos Solans(University of Oxford) CERN, Project Update 4

Recap: Motivation for IV Measurements To observe and validate possible “punch-through” effect. Sudden current spike between Substrate (depleted zone) and pwell. Caused by potential difference between pwell and sub overcoming isolation layer in between (depletion layer). Expected to occur at large potential differences between pwell and sub (also expected to see a intersection between the variable Pwell voltage and the sub voltage) Modified Process (Source from ATLAS Readout Meeting)

Setup, updated Malta Readout Meeting Measurements carried out in building 28/2-017 (Laser Telescope Lab) Using probe station setup.(Bad decision, we keep having needles broken and bad resolution of the chip, probe station now retired) Room kept at constant 21oC and stable humidity. (Again bad, we could use a fridge for the chip instead, may be expensive, but we are using fridge now)

Setup - Pwell/Sub GNDs Common Malta Readout Meeting Pwell and deep Pwell SUB V+ VRESET

Results – Pwell/Sub GNDs Common Malta Readout Meeting First two measurements, problems encountered: W12 sector example W4 sector example 104 104 Substrate Current [A] Substrate Current [A] Pwell 0.00V Pwell 1.00V Pwell 2.00V Pwell 3.00V Pwell 0.00V Pwell 1.00V Pwell 2.00V Pwell 3.00V Pwell 4.00V 10 3 10 3 Pwell 4.00V 102 Pwell 5.00V Pwell 6.00V 102 Pwell 5.00V Pwell 6.00V 10 10 1 1 101 101 5 10 15 20 Substrate Voltage [V] Behavior does not make sense, as compared with the modified CMOS process, likely due to broken chip or flawed probe station or… Breakdown voltage inversely proportional to Pwell voltage. (too strange to accept, let’s just change the setup and test again)

Setup - Pwell GND reference Malta Readout Meeting Deep Pwell (Sub-Pwell) Δ V+ VRESET All PSU GNDs are common / shorted

Results - Pwell GND reference Malta Readout Meeting W12 – E (Sub-Pwell) Δ [V] Currents observed by ΔV PSU. Breakdown voltage occurring following similar pattern to previous measurements (inversely proportional to pwell voltage). Negative currents between substrate and pwell in negative Δ regions. Punch-through defined by difference in currents observed between pwell PSU and Δ PSU (we need more example of this).

Results - Pwell GND reference Malta Readout Meeting W4-A (MALTA have 12 different sectors) Punch-through observed at lowest pwell voltages 104 Punch-Through Current [A] Punch-Through Current [A] 6000 Pwell 0.00V Pwell 1.00V Pwell 0.00V Pwell 1.00V 10 Pwell 2.00V 3 Pwell 2.00V 4000 Pwell 3.00V Pwell 4.00V Pwell 5.00V Pwell 3.00V Pwell 4.00V 2000 102 Pwell 5.00V Pwell 6.00V Pwell 6.00V 2000 4000 6000 10 1 101 5 5 10 15 20  Voltage [V] 5 5 10 15 20  Voltage [V] Current difference between Pwell PSU and ΔV PSU, which could be evidence for the punch through current. (Punch through effect proved at W4 sector)

Results – Something more Malta Readout Meeting W12 – E No punch-through observed for W12. 104 Punch-Through Current [A] Punch-Through Current [A] Pwell 0.00V 2000 Pwell 0.00V Pwell 1.00V Pwell 2.00V Pwell 1.00V Pwell 2.00V 10 3 Pwell 3.00V Pwell 4.00V Pwell 4.00V Pwell 5.00V Pwell 3.00V 102 Pwell 5.00V Pwell 6.00V Pwell 6.00V 2000 10 4000 1 6000 101 5 5 10 15 20  Voltage [V] 5 5 10 15 20  Voltage [V] Current difference between Pwell PSU and ΔV PSU. (Punch through current)

TJ-Monopix pixel matrix Pixel size: 36.4 μm x 36.4 μm, use standard process the 64x16 pixel matrix includes 8 different sectors, we use them to reset mechanism and process of the original MALTA chip 8x2 special pixels in the top corners to monitor the analogue signals on the collection electrode and front-end output for different splits 1800 µm 5000 µm TJ-Monopix with synchronization and fixes for improved charge collection

MALTA Telescope System 6 MALTA and Monopix sensor-based planes connected to 6 FPGAS Centralized powering Simulation estimates yield 3.9 um resolution (much efficient than 6 single MALTA sensors) Plan to install at CERN SPS first before apply them on ATLAS ITK Expected Beam Location