6 th Trento Workshop , March 3 rd , 2011

1

6th Trento Workshop , March 3rd , 2011

Advances in Development of 3D Silicon Detectors with CMS Pixel Readout

Ozhan Koybasi1, E. Alagoz1, A. Krzywda1 K. Arndt1, D. Bortoletto1, I. Shipsey1, G. Bolla1, T. E. Hansen2, A. Kok2, T. A. Hansen2, N. Lietaer2, G. U. Jensen2, R. Riviera3, L. Uplegger3, and S. W. L.

Kwan3

1Physics Department, Purdue University, West Lafayette, IN 47907 2036 USA‐2SINTEF, SINTEF MiNaLab, Blindern, 0314 Oslo, Norway

3Fermilab, Batavia, IL 60510 5011 USA‐

2

3D Silicon Detectors

ionizing particle

300µm

n+

p+

e

h

depletion

p-type

p+ n+

50µm

p-type

depletion

p+ and n+ electrodes are arrays of columns that penetrate into the bulk

Lateral depletion

Charge collection is sideways

Superior radiation hardness due to smaller electrode spacing: - smaller carrier drift distance - faster charge collection - less carrier trapping - lower depletion voltage

No guard rings required (active edge) Reduced dead volume

Higher noise

Complex, non-standard processing

PLANAR: 3D:

p+ active edge

O. Koybasi et al., 6th Trento Workshop , March 3rd , 2011

3

3D CMS Pixel Layouts

2 readout electrodes per pixel (2E)4 readout electrodes per pixel (4E)

Lower depletion voltage

Faster response

Lower signal loss

100 µm

150 µm

p+

n+

Lower electronic noise

Less dead volume

O. Koybasi et al., 6th Trento Workshop , March 3rd , 2011

n+: readout p+: bias

4

3D Sensor Wafer Layout

ATLAS FE-I4

ATLAS FE-I4

Medipix

Medipix

CMS

ATLAS FE-I3

4E

2E

2E4E 4E

4E

2E

2E 4E

4E 2E95 96 97 98 99 100

101 102 103 104 105 106

107 108 109 110 111 112

113 114 115 116 117 118

119 120 121 122 123

1E 1E5E

5E

2E

2E 2E

2E

3E

3E 3E

3E 3E

4E

4E

4E 4E 2E

3E4E 2E 2E4E 4E

2E 4E 2E 4E 2E

1

2 3

4 6

7 8 9

10 11

Includes ATLAS, CMS, and MediPix devices

CMS chips cover ~15% of wafer area

p-type silicon wafers with resistivity > 10 kΩ.cm

200 µm and 285 µm thick wafers processed in parallel

Well-performing sensors mostly located near the center of the wafer

O. Koybasi et al., 6th Trento Workshop , March 3rd , 2011

5

Fabrication of 3D detectors at SINTEF

P-spray inter-electrode isolation

Wafer bonded to a support wafer by Si-Si fusion bonding

Columns and active edge etched by deep reactive ion etching (DRIE)

Holes and active edge trench filled with polysilicon and doped

Column diameter: 14 µm & active edge width: 5 µm

O. Koybasi et al., 6th Trento Workshop , March 3rd , 2011

6

3D Detector Module Assembly

Sensor

Cooling tubes

Carbon fiber plate

Bias wire

VHDI

Fan-Out Opening blocked

Support waferSensor

ROCBump bonds

VHDIBase

plateAdhesive

Bias pad

Bias wire

Au plateCeramic plate

Wire

bond

3D sensors bump-bonded to CMS Pixel Readout Chip (PSI46v2) via Pb-Sn (IZM) or In bumps (SELEX)

Assembly of 3D modules was similar to the production FPIX modules except HV bias wiring

Small opening was made through carbon fiber plate at the end of the VHDI

Gold-ceramic piece was used as intermediate pad for HV wire-bonding between sensor and Fan-Out

Carbon-fiber plate was inverted on wire-bond machine to make HV bias wiring

O. Koybasi et al., 6th Trento Workshop , March 3rd , 2011

7

I-V Characteristics

0 20 40 60 80 100 120 1401E-8

1E-7

1E-6

1E-5

1E-4

Cur

rent

(A)

Voltage (V)

On wafer After wire-bondingWB5_2E_2 WB5_4E_8 WB2-16_4E_5 WB2-16_2E_6

0 20 40 60 80 1000.0

0.5

1.0

1.5

2.0

2.5

3.0

Cur

rent

(µA

)

Voltage (V)

2E 4E

Measurement TCAD simulation

Measurements done at room temperature (no cooling)

Post-assembly leakage current is lower than wafer level leakage current

Predictions of simulations are in a reasonable agreement with measurement results

Wafer level measurements were done with a temporary metal layer connecting all n-type columns. This forms an MOS structure introducing extra surface leakage current.

O. Koybasi et al., 6th Trento Workshop , March 3rd , 2011

8O. Koybasi et al., 16th RD50 Workshop ,Barcelona, June 2nd , 2010

Bump-Bond Quality

Tests done by “Modified External Calibration”

No radioactive or light source used

All sensors showed perfect bump-bond quality except one

2E Wafer B5 #2 4E Wafer B2 16 #5‐

9O. Koybasi et al., 16th RD50 Workshop ,Barcelona, June 2nd , 2010

Noise

Noise Distribution Entries : 4160 Mean : 4.52395 RMS : 0.546284

Sensor:

WB5_2E_2 (2E design, 285 µm thick)

Vbias=-40V

1 VCAL= 65.5 electrons

100µm. . .

.

.

.

.

.

.

300µm

200µm

150µm

10

Noise and Threshold

FPIX planar BPIX planar 3D with 2E configuration

3D with 4E configuration

110 155 ~450

FPIX planar BPIX planar 3D with 2E configuration

3D with 4E configuration

2870 2910 3200-5500 3200-5500

Noise:

Threshold:

250-300

O. Koybasi et al., 6th Trento Workshop , March 3rd , 2011

11

Gain Calibration

Gain curve of a single pixel

Gain determined from slope and pedestal determined from the offset of linear region by fitting the curve with the function:

2E configuration, 285 µm thick

Mean : 493.63 RMS : 11.504

Mean : 1.49061 RMS : 0.125423

ADC = p3+p2*tanh(p0*VCAL-p1)

O. Koybasi et al., 6th Trento Workshop , March 3rd , 2011

12

Efficiency Studies with Test Beam at FNAL

Charge Distribution Entries : 17834 Mean : 24542 RMS : 3887 Vbias=-40V

ADC to electron conversion: VCAL (DAC) = ADC x gain – pedestal Charge (e-) = VCAL x 65.5 – 410

Charge distribution does not have a very good convoluted Landau and Gaussian shape Gain calibration needs improvement

2E configuration, 285 µm thick

120 GeV protons

No magnetic field

O. Koybasi et al., 6th Trento Workshop , March 3rd , 2011

13

Efficiency Simulations

100 101 102 103 1040.01

0.1

1

10

MIP through n+ (readout) MIP through p+ (bias)C

olle

cted

Cha

rge

(ke- )

Fluence (1012neq

/cm2)100 101 102 103

9

10

11

12

13

14

15

16

17

Col

lect

ed C

harg

e (k

e- )

Fluence (1013neq

/cm2)

Minimum Ionizing Particle (MIP):

Efficiency= ~100% before irradiationEfficiency= ~ 35% before irradiationEfficiency= ~ 55% before irradiation

Travels vertically through substrate thicknessTrack generates 80 electron hole pairs per micron Gaussian lateral profile with 1µm standard deviation > 99.99% of charge generated within a radius of ~2.1µm

MIP through midway between n+ and p+ columns

Average Efficiency = for before irradiation

x

x

x

p+

n+

2E 4E

97.8%95.6%

Substrate thickness = 200 µm

O. Koybasi et al., 6th Trento Workshop , March 3rd , 2011

14

Efficiency Studies

0 10 20 30 40 50 60 70 80 90 10014

16

18

20

22

24

26

MPV Average PeakC

harg

e (k

e- )

Voltage (V)

2E configuration 285 µm thick

Test beam

Prediction of simulation:

Collected charge = if MIP charge is 80 electron-hole pairs per micron22.3 ke-

O. Koybasi et al., 6th Trento Workshop , March 3rd , 2011

15

Efficiency Studies with Radioactive Source (90Sr)

O. Koybasi et al., 6th Trento Workshop , March 3rd , 2011

16

Summary and Next Plans

O. Koybasi et al., 6th Trento Workshop , March 3rd , 2011

Promising results

Noise: 250-300 electrons for 2E (S/N=~90), ~450 electrons for 4E (S/N=~55)

Threshold: 3200-5500 electrons

Bump-bonding with In at SELEX is problematic

Gain calibration needs to be improved

Resolution studies in progress

3D sensors irradiated by 1.2x1014, 2x1015, 4.7x1015 (1MeV neq/cm2)

Test beam at FNAL two weeks later