1. SILVACO simulations & clean room measurements
2D structures of diode sensor with active edge and 2 GRs

2. Work environment

3. DECKBUILD Graphic front-end of every TCAD simulator of SILVACO
It provides an interactive run-time environment
Simple to use tool and it provides many automatic features (Optimizer, debugger,…)
Powerful optimizer that allows quick and accurate tuning of the simulation parameters
Good accessability thanks to many examples and tutorials

4. DEVEDIT
Allows to create structure without need of information about foundry processes
Used for creating a devices from scratch or for modifying an already existing one
It creates standard SILVACO structures that can be easily opened in the simulation tools (2D or 3D)

5. ATLAS
It provides general capabilities for phisical simulations of semiconductor devices of 2 or 3 dimensions
Given a structure file and commands to be executed, it gives in output the solution of a specific physics problem
It utilizes sophisticated numerical techniques (Gummel, Newton, …)

6. TONYPLOT
Tool for the graphic visualization (2D or 3D) of the simulation results
It allows different functions of visualizations

7. TONYPLOT examples

8. Realized simulations

9. Simulated sensor Diode sensor n-in-p 2 Guard Rings Thickness: 200 um
Pixel-trench GAP: 100 um
Peak pspray conc.: 2.5e16 cm-3

10. Plot I-V Curve
First simulations for getting confident with the environment
Ending value of simulation V_end = -500V
Breakdown ~ -300V
GR1 connected to diode pad (to simulate the presence of the readout chip FE-I4)

11. Change pspray peak and test of some ATLAS commands
Peak pspray conc. changed from 2.5e16 cm-3 to 5e16 cm-3
Check of BD simulating the voltage control on the back till -500V, the simulation stops at -300V (Error in convergence) w/o meeting the BD
Test load command: it allows to load a previous simulated str file in order to restart the simulations from that point, w/o the need to simulate again those solution (time efficient)
Test curvetrace command: it allows to switch the simulation from voltage control to current control easily
Unclear results of those commands, further tests to be done

12. Simulated sensor – w/ bridge
Diode sensor n-in-p
2 Guard Rings
Thickness: 200 um
Pixel-trench GAP: 100 um
Peak pspray conc.: 2.5e16 cm-3
Bridge for shorting the pspray implants between the metal contacts (to better emulate the 3D structure of the sensor)

13. Change of oxide value
Increasing values of the oxide concentration leads to decreasing values of BD
In these simulations was used another command of ATLAS that is the control in current with imult

14. Matlab analysis of simulated data
Thanks to extract command of DeckBuild, it has been extracted from structure files the results of the simulations and exported in .dat files so they can be read and eventually elaborated by other programs (e.g. Matlab)
3 different multiplying values of current were tested to see if it is a good and robust method to obtain results
It seems to show a trend where the higher imult leads to more result points
From this preliminary test the curves are pretty much identical, even if they are calculated in different points

15. Plot Matlab

16. Clean room measurements

17. Clean room measures
Tests on a pixel sensor (in diode config.) with different number of GRs and pixel-to-trench distance of 100um
Obtaining I-V curves at different Temperatures for both configurations: with and without GR1 connected
Less current as we go down in Temperature
From data: almost linear behaviour of the current in function of T
Activation energy not what expected (to be investigated)

18. Data results

19. ToDo
Implementation of working simulations with the commands load and curvetrace Understand why w/ GR1 connected to the pad the solutions stops before the BD Further simulations with different doses of pspray Further simulations with 3D structures Further analysis in clean room

20. Bibliografia
Silvaco, Inc., ’’DeckBuild User’s Manual’’, v R, 2015
Silvaco, Inc., ’’DevEdit User’s Manual’’, 2012
Silvaco, Inc., ’’Atlas User’s Manual Device Simulation Software’’, 2016

21. Thank you!