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Manuel Lozano

6th SILC Meeting. Torino, December 2007

Si sensor development at CNMManuel Lozano

Last developments relevant for SILC

� IR transparent detectors

� 3D technology

� Alibava Readout System

� Edgeless detectors



IR transparent detectors

� Not much developments during last months

� CNM Clean Room closed due to expansion works

� Lack of high resistivity double side polished wafers

� Common purchase from CERN

� Last week new wafers arrived

� More than one year delay

� New process run for material characterization already started

IFCA



3D technology

� Due to the low field problem of Single Sided 3D detectors, CNM decided to develop a two-side 3D technology.

� In collaboration with Glasgow University that are doing the simulations

� New mask set designed

� Technology developed

� First wafers already finished, only N-type, good results.

� 2nd and 3rd process runs started, N-type and P-type

� Very interesting for LHC pixels, very high radiation hardness. Useful for LC?



3D technology

� Schematic technology cross section

Passivation

n+ doped

55um pitch

50-0um

300-250ump- type substrate

p+ doped

10um

Oxide0.4um

1um

p+ doped

Metal

Poly 3um

OxideMetal

P-stop p+

50-0um TEOS 2um

5um

High resistivitySemiconductor

Pixel readout

Electronics chip

Solder bump

PN N



Simulations using ISE-TCAD

X (um)

Y(u

m)

0 10 200

5

10

15

20

25

80000

70000

60000

50000

40000

30000

20000

10000

0

Electric field (V/cm) in cross-sectionof double-sided detector at 100V bias

n+

p+

Electricfield (V/cm)

� 8V full depletion

(50V for planar)

Saturation at 70fF/pixel, i.e.

2.3nF/cm2 0 5 10 15 200.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

Simulated C-V characteristics of 3D detectors

Capacitance per pixel (pF)

Bias (V)

Double-sided 3D

Standard 3D



Charge collection simulation

� Simulated minimum ionizing particle

� Double-sided 3D: 2.5ns collection time

� Standard 3D: 0.5ns

� Planar detector: 10-20ns

Uniform deposition

along track0.0 0.5 1.0 1.50

2

4

6

8

10

12

14

16

18

20

22

24

MIP signals in double-sided and standard 3D at 100V

Electrode current (µΑ)

Time (ns)

Double-sided detector

Standard 3D detector



Medipix2

Diodes 2D

spreading

Test structures

Atlas pixel

3d pads

strips

Long strip

10x10 matrix

MOS

Test for SEM

3x3 matrix

Pilatus

Mask design



First wafers



Medipix2 pixel configuration

Polysilicon contactOpening in the passivation

P-type Hole Metal



Holes filled with poly and doped

Holes: 240um deepDoped polysilicon at

the bottom of the hole



SEM images of top part of holes

Polysilicon layerColumnar electrode

Metal trackPolysilicon contact



StripsPilatus

Pixels size= 172 x 172 um

Matrix = ?x?

80 um pitch

128 channels

DC coupled

Other configurations



Electrical characteristics

0 20 40 60 80 1001E-9

1E-8

1E-7

1E-6

1E-5C

urr

en

t (A

)

Reverse Bias (V)

0,10 0,15 0,20 0,25 0,30 0,35

10-8

10-7

10-6

10-5

Cu

rren

t (A

)

Forward Bias (V)

0 5 10 15 20 25 30

2,0x10-10

4,0x10-10

6,0x10-10

8,0x10-10

1,0x10-9

1,2x10-9

1,4x10-9

1,6x10-9

1,8x10-9

2,0x10-9

2,2x10-9

Capacitance (F)

Bias(V)

Full depletion occurs at 2-3 V since the electrode pitch is 55µm

0 10 20 30 40 501E-10

1E-9

1E-8

1E-7

Current(A)

Reverse bias(V)

pad 1

pad 2

pad 3

pad 4

pad 5

55um pitch



ALIBAVA: A readout system for microstripsilicon sensors

� Joint development of Liverpool Univ., IFIC-Valencia and CNM-Barcelona

� Need of a simple and cheap system for detector charge collectionperformance characterization

� Difficulty for obtaining this type of measurements:

� Required equipment is expensive

� A large number of channels has to be monitored

� Many different approaches: NIM, CAMAC, VME or custom electronic module

� Testing with an electronic system as similar as possible to those used at LHC experiments:

� LHC front end readout chip should be used

� Analog readout is preferred for pulse shape reconstruction



System characteristics

� The system is compact and portable.

� Two triggering options:

� External trigger input from one or two photomultipliers (radioactive source).

� Synchronized external trigger output for pulsing an external excitation source (laser system).

� Uses one or two front-end readout chips (Beetle, LHCb) to acquire the detector signals

� Communicates with a PC via USB,

� The system is controlled from a PC application in communication with a FPGA which interpret and execute the orders.

� It has its own power supply system, from AC mains (not HV).

Motherboard prototypeprototype

Test box” (DB + fanins + detector)



Edgeless detectors

� RIE cut trenches reduces inactive detector area due to gurad rings

� With trenches and saw cut, we estimate inactive are in the order of 100 µm

� Using Current Terminating Ring (CTR) to collect current, as small as 25 µm

� Important for detector tiling

Strips Guard ring Current Terminating Ring

25µm



Final remarks

� We can manufacture detectors for the SILCcollaboration

� Only 4’’ wafers

� Even with two metals

� Good option to test new ideas

� Easy access through the Spanish “Access to Large Facilities” Program

http://www.cnm.es/gicserv/index.htm

� Deadline of next call: 31 January 2008

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Hagaclicpara modificarel estilode textodel patrón Si ... · Hagaclicpara modificarel estilode textodel patrónSi sensor developments at CNM Manuel Lozano. 6th SILCMeeting. ... Test