Fabrication process validation for a double sided Silicon pixel detector.

F. Quarati, S. Cadeddu, A. Lai

A. Sesselego, M. Caria

Physics Dep., University of Cagliari, ItalyPhysics and Astronomy Dep., University of

Glasgow, United Kingdom

Detector features and measurements equipment

• High resistivity n-type silicon bulk wafer

• Boron implantation • 3 detector for each wafer • Detector area 2.8 x 3.8 cm2

• No. of pixes 16512 [IWORID 2001]

• Probe station K .Suss• Keithley 237 source meter• Keithley 2400 source meter• Keithley 590 CV analyzer• Deuterium lamp

Hamamatsu• Monochromator Y. Jobin

Processed at COLIBRISNeuchatel, Switzerland

Characteristics of the standard detector:

responsivity

• The slope is regular after 5 V of bias

-20

-15

-10

-5

0

5

10

15

-1 4 9 14 19 24

bias [V]

Signal [nA]

dark

UV radiation

Characteristics of the standard detector:depletion

• The depletion begin at low bias

0,5

0,6

0,7

0,8

0 5 10 15 20 25

bias [V]

capa

city

[pF

]

1cost V+

Characteristics of the standard detector:

single pixel depletion

• The CV is reached biasing all the detector

0,05

0,1

0,15

0 5 10 15 20 25

bias [V]

capa

city

[pF

]

1cost V+

Validation examples with collected signal (UV-dark)

• The graf. show the current value difference between UV - dark

4,5

5,5

6,5

7,5

8,5

0 5 10 15 20 25bias [V]

current [nA]

STD

bad

good

bad: swing

Complete validation with CV charac.

• The CV comparison provide that the deplation condition is also well satisfy

0,5

0,6

0,7

0,8

0 5 10 15 20 25

bias [V]

capa

city

[pF

] STD detector &previous good detector

The validation of the production process

• 24 wafer or 72 detector are been processed

• 1 wafer present C.C. for all the 3 detector

2 wafer present high noise for all 3 detector

That is 13%• 8 detector present high

noise That is 11%• 3 detector present

swing That is 4%• 21 wafer and 52

efficient detectors

72%

11%

4%

13%

detector pie

Further work

• Fit with the exponential addition is better

0,5

0,6

0,7

0,8

0 5 10 15 20 25bias [V]

capacity [pF]

2 0.0003c =

2 0.0005c =

2

1

cost1cost

VeV

-µ +

+