1. Design and Characterization of a Novel, Radiation-Resistant Active Pixel Sensor in a Standard 0.25 m CMOS Technology
P.P. Allport, G. Casse, A. Evans, M. Tyndel, R. Turchetta, J.J. Velthuis, G. Villani

2. CMOS APS detectors: principle & characteristics
Outline
CMOS APS detectors: principle & characteristics
Novel CMOS detector structure
HEPAPS3
Conclusions

3. readout control MAPS CMOS detectors Column parallel ADC
3 MOS APS structure
Data processing -out stage
Detector and readout integrated onto the same substrate

4. CMOS detectors for HEP Nwell Pwell Pepi P++- -
Pepi + -
P++
Internal electric field 3D view
Vbias = 2V applied to N+ Well
Generated charge diffuses through
epitaxial layer and substrate until
recombines or gets collected by cathode
30 ns Transient Electron Current

5. CMOS detectors for HEP-Charge collection and response time
epi
subs
Reference : HEPAPS μm CIS TSMC
Simulated ∆v in-cell
Tests results ∆v in-cell

6. CMOS detectors for HEP-Radiation Hardness
T = 300 K
T = 253 K
No RAD
RAD 1014
J. Velthuis University of Liverpool
Example of simulation radiation degradation
@ to bulk damage Ф = GeV p
Example of S/N calculation under Hard Reset assumption Vbias = 2V
HEPAPS μm CIS TSMC
Test results S/N ratio vs number of pixels
Charge collected mainly by diffusion: Radiation Bulk damage seriously impacts onto charge collection efficiency

7. Novel CMOS structure for HEP
Deep N Well process allows electric field to be introduced into active region
Deep N Well
Cell structure comparison
Internal electric field plot N P
epi
subs

8. Deep N Well Epi collected charge
HEPAPS DNW-Epi simulation
conditions:
Vbias = 2V
Cstray = 2 fF
Tint = 20 ns
3x3 Cells ( size 15x15 m)
HEPAPS DNW-Epi Heavy Ion MIP Simulation Results:
Collection time max: 8 nS
<Collected charge> (Ф = 0) = 261 e-
<Voltage Drop> (Ф = 0) = 1.8 mV
Leakage Current (Ф = 0 ) 65 fA
Capacitance ( Ф = 0 ) 22 fF
Ilk vs. bias voltage
Capacitance vs. bias voltage

9. Radiation Hardness and Signal to noise ratio comparison
Deep N Well Epi Example of S/N calculation
HR Vbias = 2 APS μm DNW 8 m Epitaxial layer TSMC MS
No RAD
RAD 1014
HEPAPS2 Example of S/N calculation
HR Vbias = 2 APS μm 8 m Epitaxial layer TSMC CIS

10. HEPAPS3 Deep N Well N P
subs
HEPAPS3: No Epitaxial layer, Lowly Doped Substrate TSMC MS
Slower collection
Higher spread
Charge collected much dependent on diffusion in undepleted substrate
HEPAPS3 Simulation Results:
Collection time max: 14 nS
<Collected charge> (Ф = 0) = 338 e-
<Voltage Drop> (Ф = 0) = 1.9 mV
Leakage Current (Ф = 0 ) 65 fA
Capacitance ( Ф = 0 ) 26 fF
TSMC MS 0.25 m
No epitaxial layer
Different flavors on chip

11. HEPAPS3 test results J. Velthuis University of Liverpool
HEPAPS3: example of noise signal distribution DNW
HEPAPS3: No Epitaxial layer Lowly Doped Substrate TSMC MS
Large signal
Huge cluster size( charge diffusion trough undepleted substrate)
HEPAPS3: example of cluster signal distribution DNW
106Ru source
HEPAPS3: example of cluster in S/N
106Ru source

12. Conclusions
Topology optimization of MAPS still ongoing, but future HEP experiments call for
uncompromisingly high radiation resistant structures
Deep N Well with Epitaxial layer introduces drift component in collection charge process
HEPAPS3 preliminary tests results and simulations suggest Deep N Well process
with epitaxial layer might show good performances at high level of radiation
Synergy between new design topologies and Deep N Well process required
to fully exploit the potential benefits

13. HEPAPS2 simulation 4 Diodes version
Cell structure
Simulation shows better charge collection at 1014 Irradiation
Tests ongoing