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MAPS Monolithic Active Pixel Sensors

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					Rutherford Appleton Laboratory Particle Physics Department

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

G. Villani

IEEE NSS

Rome, October 2004

Rutherford Appleton Laboratory Particle Physics Department

Outline

• • • •

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

G. Villani

IEEE NSS

Rome, October 2004

Rutherford Appleton Laboratory Particle Physics Department

≈10

MAPS CMOS detectors

r e a d o u t
Column parallel ADC Data processing -out stage

c o n t r o l
3 MOS APS structure
Detector and readout integrated onto the same substrate

G. Villani

IEEE NSS

Rome, October 2004

Rutherford Appleton Laboratory Particle Physics Department
CMOS detectors for HEP
Nwell
+ + + + + -

Pwell Pepi

P++

Generated charge diffuses through epitaxial layer and substrate until recombines or gets collected by cathode

Internal electric field 3D view Vbias = 2V applied to N+ Well

30 ns Transient Electron Current

G. Villani

IEEE NSS

Rome, October 2004

Rutherford Appleton Laboratory Particle Physics Department
CMOS detectors for HEP-Charge collection and response time
N

P

epi

subs

Reference : HEPAPS2 0.25 μm CIS TSMC

Simulated ∆v in-cell

Tests results ∆v in-cell

G. Villani

IEEE NSS

Rome, October 2004

Rutherford Appleton Laboratory Particle Physics Department
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 = 1014 24GeV p

S x, y, t int   N e - rms



ncoll x, y 
2 RST

 e - rms

2 int egr



0.5

Example of S/N calculation under Hard Reset assumption Vbias = 2V HEPAPS2 0.25 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 G. Villani IEEE NSS Rome, October 2004

Rutherford Appleton Laboratory Particle Physics Department
Novel CMOS structure for HEP
Deep N Well process allows electric field to be introduced into active region

Deep N Well

Cell structure comparison
N P

Internal electric field plot

epi

subs

G. Villani

IEEE NSS

Rome, October 2004

Rutherford Appleton Laboratory Particle Physics Department
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 G. Villani IEEE NSS

Capacitance vs. bias voltage Rome, October 2004

Rutherford Appleton Laboratory Particle Physics Department
Radiation Hardness and Signal to noise ratio comparison

Deep N Well Epi Example of S/N calculation HR Vbias = 2 APS2 0.25 μm DNW 8 m Epitaxial layer TSMC MS

No RAD

RAD 1014

HEPAPS2 Example of S/N calculation HR Vbias = 2 APS2 0.25 μm 8 m Epitaxial layer TSMC CIS

G. Villani

IEEE NSS

Rome, October 2004

Rutherford Appleton Laboratory Particle Physics Department
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

TSMC MS 0.25 m No epitaxial layer Different flavors on chip G. Villani

Capacitance ( Ф = 0 ) 26 fF

IEEE NSS

Rome, October 2004

Rutherford Appleton Laboratory Particle Physics Department
HEPAPS3 test results

J. Velthuis University of Liverpool

HEPAPS3: example of noise signal distribution DNW

HEPAPS3: example of cluster in S/N 106Ru source

HEPAPS3: No Epitaxial layer Lowly Doped Substrate TSMC MS HEPAPS3: example of cluster Large signal signal distribution DNW Huge cluster size( charge diffusion 106Ru source trough undepleted substrate) IEEE NSS Rome, October 2004

G. Villani

Rutherford Appleton Laboratory Particle Physics Department
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

G. Villani

IEEE NSS

Rome, October 2004

Rutherford Appleton Laboratory Particle Physics Department
HEPAPS2 simulation 4 Diodes version

Cell structure

Simulation shows better charge collection at 1014 Irradiation Tests ongoing
G. Villani IEEE NSS Rome, October 2004


				
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