Claudio Piemonte Trento, 13-14 Feb. 2006 2 nd Trento workshop Device simulation of...

Claudio Piemonte Trento, 13-14 Feb. 20062nd Trento workshop

Device simulationDevice simulationof Single-Type-Column 3D silicon detectorsof Single-Type-Column 3D silicon detectors

Claudio PiemonteITC-irst Trento (Italy)

[email protected]


OutlineOutline

• Introduction

• Single-Type Column 3D detector concept

• Simulation of the static characteristics

• Simulation of the signal response

• Conclusion


IntroductionIntroduction

Development of 3D sensors is being carried out at ITC-irst incollaboration with INFN.

Work done so far is described in 3+1 talks:

• Simulations of 3D-STC detectors - Claudio Piemonte (ITC-irst)

• Technology used in the first two fab. runs - Sabina Ronchin (ITC-irst)

• Electrical characterization of first prototypes - Nicola Zorzi (ITC-irst)

+

• Electrical characterization at Glasgow - D. Pennicard

(Glasgow University)


““Standard” 3D detectorsStandard” 3D detectors - concept - concept

Proposed by Parker et al. NIMA395 (1997)

n-columns p-columns

wafer surface

ionizing particle

Short distance between electrodes:• low full depletion voltage• short collection distance more radiation tolerant than planar detectors!!

n-type substrate


Single-Type-Column 3D detectorsSingle-Type-Column 3D detectors - concept - concept

Sketch of the detector:

grid-like bulk contact

ionizing particle

cross-sectionbetween twoelectrodes

n+ n+

electrons are swept away by the transversalfield

holes drift in the central region and diffuse towards p+contact

n-columns

p-type substrate

Functioning:

[ Presented in June 2004 at the Hiroshima conference ]


3DSTC detectors3DSTC detectors - concept (2) - concept (2)

Main feature: hole etching and doping are performed only once

Further simplification: holes not etched all through the wafer

p-type substraten+ electrodes

Uniform p+ layer

Bulk contact is provided by a backsideuniform p+ implant single side process.

No need of support wafer.


Structure used for static simulationsStructure used for static simulations

3D simulations are necessary DEVICE3D tool by Silvaco

Important to exploit the structuresymmetries to minimize the regionto be simulated

n+

cell50m

• p-type substrate

• Wafer thickness:300m

• Holes: 5m-radius

250m-deep


Simulated potential distribution (1)Simulated potential distribution (1)

Potential distribution (vertical cross-section)

Potential distribution(horizontal cross-section)

null field lines

50m

300

m

0V

-10V

-5V

-15V

in scale

not in scale


Potential and Electric field along a cut-line from the electrode to the center of the cell

To increase the electric field strength one can act on the substrate doping concentration

Na=1e12 1/cm3

Na=5e12 1/cm3

Na=1e13 1/cm3

Na=1e12 1/cm3

Na=5e12 1/cm3

Na=1e13 1/cm3

Simulated potential distribution (2)Simulated potential distribution (2)


Capacitance in 3D-STCCapacitance in 3D-STC

diode =matrix of

10x10 holes

Back

CbackTotCintTot

Structure for simulation of Cback

half pitch

Cback=4 x simulated value

Structure for simulation of Cint

Cint=2 x simulated value

oxide notincluded inthe structure

guard ring

3D diode

Cback=CbackTot/100

Cint=CintTot/40


0.0E+00

1.0E-14

2.0E-14

3.0E-14

4.0E-14

5.0E-14

6.0E-14

7.0E-14

0 10 20 30 40 50Bias (V)

Ca

pa

cita

nce

(F

)

Cback

Pitch=80um,Hole diam=10+4um Freq=100kHz

Cint

Capacitance simulation on a 300m thick wafer with 150m deep columns, 80m picth, Na=5e12cm-3

Capacitance simulations (1)Capacitance simulations (1)

Phase 1

Phase 2

• high Cback

• ~ zero Cint

• max Cint

• slowly dec. Cback

Phase 1 Phase 2

undepleted Si

undepleted Si


0.0E+00

1.0E-14

2.0E-14

3.0E-14

4.0E-14

5.0E-14

6.0E-14

7.0E-14

8.0E-14

9.0E-14

1.0E-13

0 10 20 30 40 50 60Bias voltage (V)

Ca

pa

cita

nce

(F

)

pitch=100um

pitch=80um

pitch=80um simulation

100kHz col 190

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 10 20 30 40 50 60Bias Voltage (V)

C^-

2 (

pF

^-2

)

pitch=100um

pitch=80um




Comparison between measurements (on 3D diodes) and simulations

100m col. pitch

80m col. pitch

100m col. pitch

80m col. pitch

1/C2 characteristic

• 300m thick wafer • 190m deep columns• 2e12cm-3 subst. conc.

From 1/C2 curves:• full depl. between columns clearly

visible (higher for 100m pitch)• diode-like behavior in phase 2

col-to-back capacitance

meas.

simul.



1) Vbias=0V 2) Vbias=2V 3) Vbias=5V 4) Vbias=20V

The 1/C2 curve of the col-to-backcapacitance can be used to extractboth the intercolumn as well asthe col-to-back full depletion.

0.0

1.0

2.0

3.0

4.0

5.0

0 10 20 30 40 50 60Bias Voltage (V)

C^-

2 (

pF

-2)

pitch=80um


2 3

4

Do not consider the hot spot in the pictures,it is the charge released by a particle.


0.0E+00

2.0E-10

4.0E-10

6.0E-10

8.0E-10

1.0E-09

1.2E-09

1.4E-09

1.6E-09

0.0E+00 5.0E-10 1.0E-09 1.5E-09 2.0E-09 2.5E-09Time (s)

Cu

rre

nt

(A)

0.0E+00

2.0E-10

4.0E-10

6.0E-10

8.0E-10

1.0E-09

1.2E-09

1.4E-09

1.6E-09

0.0E+00 5.0E-10 1.0E-09 1.5E-09 2.0E-09 2.5E-09Time (s)

Cu

rre

nt

(A)

Signal in 3D-STC detectors (1)Signal in 3D-STC detectors (1)

e hFirst phase Transversal movement

generation10m from

column

generationin the middlebetween two

columns

induced by einduced by h

1 2

34

induced by einduced by h

1 2

34

)(

)()()()()(

x

xxxx

v

FEFvx

t

qqxik

Ramo theorem:

electricfield

weightingfield

50m

250

m50

m


0.0E+00

2.0E-12

4.0E-12

6.0E-12

8.0E-12

1.0E-11

1.2E-11

0.0E+00 5.0E-08 1.0E-07 1.5E-07Time (s)

Cu

rre

nt

(A)

Signal in 3D-STC detectors (2)Signal in 3D-STC detectors (2)

Second phase Hole vertical movement

180um from top 140um from top

hole velocity orthogonal to weighting field no signal induced

weighting field no longer orthogonal signal induced

a hole moving towards the backinduces a current pulse shifted in time according to the generationdepth


0.0E+00

1.0E-07

2.0E-07

3.0E-07

4.0E-07

0E+00 1E-09 2E-09 3E-09 4E-09 5E-09Time (s)

Cur

rent

(A

)

el 1

Simulation of a localized charge depositionSimulation of a localized charge deposition

Only the transversal movementis visible

The current plot in log-log scaleshows very clearly the fast transversal component and theslow hole vertical one.

1 2

34

0 x

y

1.0E-13

1.0E-12

1.0E-11

1.0E-10

1.0E-09

1.0E-08

1.0E-07

1.0E-06

1E-12 1E-11 1E-10 1E-09 1E-08 1E-07 1E-06 1E-05 1E-04Time (s)

Cu

rre

nt

(A)

el 1

transv. movem. vert. movem.

induced by einduced by htotal current

1 3

0

z

(10,10) 80m

50m

250m

50m

electrons

holes


1 2

34

Simulation of a uniform charge deposition (1)Simulation of a uniform charge deposition (1)

Uniform Vertical deposition centered @ (10,10)Bias voltage = 50V (> full depl.)

All the electrons collected by electrode 1

-2E-06

-1E-06

0E+00

1E-06

2E-06

3E-06

4E-06

5E-06

6E-06

7E-06

0E+00 1E-09 2E-09 3E-09 4E-09 5E-09Time (s)

Cur

rent

(A

)

el 1

el 2

el 3

el 4

back

1E-13

1E-12

1E-11

1E-10

1E-09

1E-08

1E-07

1E-06

1E-05

1E-12 1E-11 1E-10 1E-09 1E-08 1E-07 1E-06 1E-05 1E-04Time (s)

Cur

rent

(A

)

elctrons

holes

el 1

electron collection peak

vertical holemovement

transversal holemovement

induced by einduced by htotal current

log-log plot

linear scale plot


1 2

34

Simulation of a uniform charge deposition (2)Simulation of a uniform charge deposition (2)

Uniform Vertical deposition centered @ (25,25)Bias voltage = 50V (> full depl.)

Electrons equally shared between four columns same signals on the four columns

1.0E-13

1.0E-12

1.0E-11

1.0E-10

1.0E-09

1.0E-08

1.0E-07

1.0E-06

1E-12 1E-11 1E-10 1E-09 1E-08 1E-07 1E-06 1E-05 1E-04Time (s)

Cur

rent

(A

)

elctrons

holes

el 1 - 50V

-5E-07

-4E-07

-3E-07

-2E-07

-1E-07

0E+00

1E-07

2E-07

0E+00 1E-08 2E-08 3E-08 4E-08 5E-08Time (s)

Cu

rre

nt

(A)

el 1 - 50V

el 2

el 3

el 4

back

log-log current plot

linear-scale current plot


In the worst case of a track centered the central region, 50% of the charge is collected at t ~ 300ns

Outside this region, 50% of the charge is collected within 1ns.

Full charge collection timeFull charge collection time

1 2

34

(25,25)(20,20)(10,10)

1E-13

1E-12

1E-11

1E-10

1E-09

1E-08

1E-07

1E-06

1E-05

1E-12 1E-11 1E-10 1E-09 1E-08 1E-07 1E-06 1E-05 1E-04Time (s)

Cur

rent

(A

)

250um_20-20

250um_25-25

250um_10_10

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1E-12 1E-11 1E-10 1E-09 1E-08 1E-07 1E-06 1E-05 1E-04Time (s)

Co

llect

ed

ch

arg

e (

a.u

.)

250um_25-25

250um_20-20

250um_10-10

Same Vbias, different impact point

tail independent from impact position

charge collectedis ¼ for interactionin the middle point


ConclusionConclusion

3D-STC detector: • Advantage: “simple” fabrication process.• Disadvantage: Very long full charge collection times.

=>

• extremely interesting device to tune the technology for

the production of standard 3D detectors• can be used in those applications not requiring

charge information in short time


Additional slides


CCE versus bias voltageCCE versus bias voltage

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 10 20 30 40 50 60Bias Voltage (V)

C-2

(p

F-2

)

pitch=100um

pitch=80um



1.00E-13

1.00E-12

1.00E-11

1.00E-10

1.00E-09

1.00E-08

1.00E-07

1.00E-06

1.00E-05

1.0E-12 1.0E-11 1.0E-10 1.0E-09 1.0E-08 1.0E-07 1.0E-06 1.0E-05 1.0E-04

Time (s)

Cu

rre

nt (

A)

Vbias=0.1V

Vbias=5V

Vbias=20V

Vbias=30V

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 5 10 15 20 25 30

Bias Voltage (V)

CC

E

Vbias=2V

Claudio Piemonte Trento, 13-14 Feb. 2006 2 nd Trento workshop Device simulation of...

Documents

Transcript of Claudio Piemonte Trento, 13-14 Feb. 2006 2 nd Trento workshop Device simulation of...