Irradiation at IUCF

• We irradiated 5 chips from Sintef wafer 9 (7,39,42,44,46) at Indiana University Cyclotron Facility on 30th November.

• Pixel 7,44 and 46 are baseline design. Pixel 42 spiral ring and pixel 39 single ring design.

• Pixel 7,39,42 and 46 were exposed to a fluence of 1x1014 p/c.m.2. Pixel 44 were exposed to 6x1014 p/c.m.2

• We measured the properties of the chips at 210 C, -50 C & -100 C

Pixel side up

Conducting rubber sheet

Wire bond Wire bond (1st GR)

Cutape

Cutape

Guard RingsDiode N+ ring

Ammeter Hi

Wire

Bulk Material

N+

P+

Pixels are bumped but not bonded with anything. The whole structure was keptinside the refrigerator and the wire came out of the refrigerator.

Measurement Technique

What we expected

•Increase in current I=.V.eq (This equation gives the change of current in the

plateau region of the IV curve. For these pixels the plateau region is between 50V to 250V)

= 4.0x10-17 A/cm1 , V = 0.007478 cm3 eq = 1(6)x1014 cm-2

I = 3.0x10-5 (17.9x10-5) A

•A single pixel - 0.015x0.015 cm2

•Increase in current through a single pixel Isingle pixel = I x 0.015x0.015/(0.2493) A = 27.0 (162) nA

1Value of from Rose Collaboration - http://www.physics.purdue.edu/vertex/talks/feick.pdf

What we got

• For Pixel 7 I200V = 2.67x10-5 A I300V = 6.94x10-5 A • For Pixel 39 I200V = 3.11x10-5 A I300V = 4.98x10-5 A

•For Pixel 42 I200V = 2.80x10-5 A I300V = 5.69x10-5 A

•For Pixel 46 I200V = 2.85x10-5 A I300V = 3.90x10-5 A]

•For Pixel 44 I200V = 1.16x10-4 A I300V = 2.77x10-4 A

Pixel 44 received 6 times higher fluence than the other pixels. Leakage current of pixel 44 is 4(5) times higher than the other pixels at 200(300)V.

Pixel # Design Fulence-5 C -10 C -5 C -10 C

7 Double open ring 1E+14 324 340 470 478

46 Double open ring 1E+14 354 392 486 510

44 Double open ring 6E+14 236 298 502 598

39 Single close ring 1E+14 322 370 472 492

42 Double spiral ring 1E+14 364 402 490 514

Average of 1e14 341 376 479.5 498.5

10nA/pixel at 100nA/pixel at

Comparison

Pixel 46

Design A

Fluence -1x1014

Leakage Current at different TempSINTEF W9 P46 - 1x10e14

1.00E-07

1.00E-06

1.00E-05

1.00E-04

1.00E-03

2 102 202 302 402 502

Reverse Bias (V)

Leak

age

Cur

rent

(A)

-5 C

-10 C

21 C

392 510354 486

10nA/pixel 100nA/pixel

Leakage Current - SINTEF W9 P46-10 C

1.00E-07

1.00E-06

1.00E-05

1.00E-04

1.00E-03

0 100 200 300 400 500

Reverse Bias (V)

Lea

kag

e C

urr

en t

(A)

Diode Current

Guard Ring Current

This indicates that the current is coming from diode (pixels).

Current compliance was 1mA

Extra Current

Pixel 7 - Depletion Voltage

Design A

Fluence -1x1014SINTEF W9 P7- After Radiation

1/C^2

0.00E+00

5.00E+20

1.00E+21

1.50E+21

2.00E+21

2.50E+21

3.00E+21

3.50E+21

4.00E+21

4.50E+21

5.00E+21

0 20 40 60 80 100 120 140

Reverse Bias (V)

1/C

^2

- (F

^-2

)

100 Hz

500 Hz

1KHz

Full Depletion at 33 V

Leakage currentat depletion voltage is 0.71A (1.1nA/pixel)

Summary• We have to understand the rise of current at the kink

between 200 to 300V.

• We plan to do the measurement at -20

• We plan to bump bond this pixel arrays to ROC and to measure them with source.

Is it possible to measure the potential of a central pixel when the guard region is biased ?

Silver Epoxy

Pixel

•First the measurement was done without grounding the epoxy.•Next the measurement was done with the epoxy grounded.•Measurement was done with one probe at the center pixel, one probe at the silver epoxy and a wire bond connection with the diode.

Voltage at a Pixel

-20

-18

-16

-14

-12

-10

-8

-6

-4

-2

0

-300-250-200-150-100-500

Reverse Bias (V)

Vo

ltag

e at

cen

ter

pix

el (

V)

Epoxy not grounded

Epoxy grounded

This measurement was done on SINTEF wafer 24 Pixel 46 before irradiation. We haven’t done the measurement after irradiation.

Connection Setup for measuring the voltage at a center Pixel

Wire bond Guard RingsDiodeN+ ring

Hi

Probe

Bulk Material

N+

P+

V

Probe

InteriPixel CapacitanceSintefW24P46

1.00E-15

1.00E-14

1.00E-13

1.00E-12

1.00E-11

-350-300-250-200-150-100-500

Cap

acit

ance

(F

)

Pixel-Pixel 10KHz

Pixel-Pixel 100KHz

Pixel-Pixel 1MHz

Epoxy-Pixel 10KHz

Epoxy-Pixel 100KHz

Epoxy-Pixel 1MHz

Interpixel Capacitance CSEM W2 P20

1.00E-16

1.00E-15

1.00E-14

1.00E-13

1.00E-12

-350-300-250-200-150-100-500

Cap

acit

ance

(F

)

10KHz

100KHz

1MHz

Inter Pixel Capacitance before irradiation

Connection Setup for measuring the Interpixel Capacitance

Wire bond Guard RingsDiodeN+ ring

Hi

Probe

Bulk Material

N+

P+

C

Probe

~