1
Simulations of irradiated MSSDs with p-stop
Parameter Value
n+ / p+ doping [cm-3] 5e18
Neff (320P) [cm-3] 3.4e12
Neff (200P) [cm-3] 3e12
Neff (120P) [cm-3] 1.5e12
implant thickness [µm] 1.5
backplane diffusion depth (320P) [µm]
33
backplane diffusion depth (200P) [µm]
115
backplane diffusion depth (FTH200P) [µm]
10
backplane diffusion depth (120P) [µm]
215
Np [cm-3] 3e16, 4e16, 5e16
p-stop thickness [µm] 0.5, 1.0, 1.5
SiO2 thickness [µm] 0.5
T [K] 253, 273, 293
area factor 30490
F (Cint) 1.0 MHz
F (Cback) 1.0 kHz
Qf (irr.) [cm-2] 1e12 [1]
Qf (unirr.) [cm-2] 1e10, 5e10, 4e11
5-strip structure for 7-80 and 5-120 regions
Two-level radiation damage model [1]
Level [eV]
σn [cm-2]
σp [cm-2]
Introduction rate [cm-1]
EC - 0.42 2e-15 2e-14 1.613EC - 0.46 5e-15 5e-14 0.9
1 MeV neutron equivalent doses for the simulations (from CMS irr. campaign)
Device thickness[μm]
Proton 1 MeV neqv fluence[cm-2]
1 MeV n fluence[cm-2]
1 MeV neqv summed fluence[cm-2]
≥ 200 3.0e14 4.0e14 7.0e14
≥ 200 1.0e15 5.0e14 1.5e15
≥ 200 1.5e15 6.0e14 2.1e15
≤ 200 3.0e15 7.0e14 3.7e15
< 200 1.3e16 1.0e15 1.4e16
p-stop configurations (preliminary)
p-stop count p-stop width[µm]
spacing[µm]
2 2 10
2 4 6
1 14 0
Total p-stop width = constant
[1] M. Petasecca et al. NIM A 563 (2006) 192-195.
2
• By lowering the value of Qf from 5e10 cm-2 to 2.7e10 cm-2 the initial dip of measured curve is produced by simulation. At higher voltages simulated curve is within ~2 % of measurement.
• At higher value of non-irradiated inversion layer oxide charge Qf = 4e11 cm-2 simulation does not match the measurement and fails at ~600 V due to high E at p-stop edges.
• For the irradiation simulations, p-stop depth was varied by dp = 1.0 and 1.5 μm
• Irradiated inversion layer oxide charge Qf = 1e12 cm-2
region 5
region 7
TEST ID: 15010
TEST ID: 15016
• Simulation dp = 1.5 μm
• Qf = 5e10 cm-2
Interstrip capacitances of measured and simulated non-irradiated 200P detectors @ +20 °C
Initial dip not produced by simulation
• Simulation dp = 1.5 μm
• Qf = 5e10 cm-2
region 7
• Simulation dp = 1.5 μm
• Qf = 2.7e10 cm-2
TEST ID: 15016
3
• Are the strips are short-circuited for Np = 3e16 until Vd has removed electrons from the inversion layer?
• e- density between two strips and p-stops for
Φ = 7e14 cm-2 and wp = 2μm. Isolation fails for smaller Np @ low Vd?
• Widest wp has the lowest Cint and Vd where minimum Cint is reached for Np = 3e16
Cback
Cint
Qf = 1e12 cm-2
p-stop thickness = 1.0 μm
f = 1.0 kHz
f = 1.0 MHz
Irradiated 200P 7-80 region for varying Np and p-stop count/width @ -20 °C
• Radiation damage removes electrons from the inversion layer → isolation reached at lower Vd?
4
p-stop thickness = 1.0 μm
Cint Cback • At higher T electrons removed
from inversion layer more quickly → min. Cint reached at lower Vd 350 V (-20 °C) → 290 V (+20 °C)
• e- density between two strips and p-stops for
Φ = 7e14 cm-2 and wp = 2μm
Irradiated 200P 7-80 region for varying Np and p-stop count/width @ +20 °C
5
Irradiated 200P 7-80 region for varying Np and p-stop count/width @ -/+20 °C
p-stop thickness = 1.5 μm = implant thickness
Cint @ -20 °C
Ileak @ -20 °C
• e- density between two strips and p-stops for Φ = 7e14 cm-2 and wp = 2μm
Cint @ +20 °C
Ileak @ +20 °C
n @ -20 °C
n @ +20 °C
• No step in leakage current
observed for both Np
• No high values of Cint observed
after ~30 V
• Low e- density even at
low voltage for both Np
Superior configuration to dp = 1.0 μm