St Malo, 13th April 2002 Václav Vrba, Institute of Physics, AS CR 1

Václav Vrba

Institute of Physics, AS CR, Prague

Silicon pad sensors for W-Si ECal

St Malo, 13th April 2002 Václav Vrba, Institute of Physics, AS CR 2

Outline

• Sensor tile outer dimensions

• Pad array design consideration

• Time schedule - towards the first prototype

• Tests outlines

St Malo, 13th April 2002 Václav Vrba, Institute of Physics, AS CR 3

Sensor tile outer dimensions

Outcome from the meetingat EP:

- 4” high resistivity wafers- tile side: 62.0+0.0 -0.1 mm- scribe line: 100 m- scribe safety zone: 200 m- guard ring width: cca 750 m (cca 1.5 * wafer thickness)

The dead zone width is about 1 mm

Wafer book keeping information

1.0 mm

St Malo, 13th April 2002 Václav Vrba, Institute of Physics, AS CR 4

Pad array design consideration

Along with the diodes, the technique used for fabrication of bias resistors and coupling capacitors represents an important issue:

a) polysilicon resistors – production of the tile needs about 7-8 masks; can be the source of additional yield reduction.

b) punch through resistors – production of the tile needs about 5 masks; easy to produce – needs to check whether required parameters can be achieved.

c) deposited resistors (amorphous silicon) – achievement of EP;

- needs about 4-5 masks for production of the diodes array; on top of that additional fabrication of resistor and capacitors.

d) ion implantation resistors – not considered here.

St Malo, 13th April 2002 Václav Vrba, Institute of Physics, AS CR 5

Design consideration: Polysilicon resistors

Bias resistor

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Coupling capacitor

Direct contact on diode – e.g. for testing

Bias lines

St Malo, 13th April 2002 Václav Vrba, Institute of Physics, AS CR 6

Design consideration: Polysilicon resistors

St Malo, 13th April 2002 Václav Vrba, Institute of Physics, AS CR 7

Design consideration: Punch through resistors

Coupling capacitor

Direct contact on diode – e.g. for testing

Bias resistor

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Bias lines

St Malo, 13th April 2002 Václav Vrba, Institute of Physics, AS CR 8

Deposited resistors – before deposition

St Malo, 13th April 2002 Václav Vrba, Institute of Physics, AS CR 9

Deposited resistors – after deposition

Bias lines

e.g.Wire bonding, Flex cable gluing, etc.

St Malo, 13th April 2002 Václav Vrba, Institute of Physics, AS CR 10

Design consideration: a partial summary

a) polysilicon resistors:

- should not be a problem to have resistors 10 M;

- capacitors 1-10 nF.

b) punch through resistors:

- resistors to be tested; if acceptable then it is a simple solution;

- capacitors as a).

c) deposited resistors:

- will be considered in the first prototype submission to test the deposition technology of capacitors and resistors

Compatibility of process for variants a), b) and c) on one wafer? To

try all variants separately could be quite costly! Option c) as a

baseline for main sensor tile?

St Malo, 13th April 2002 Václav Vrba, Institute of Physics, AS CR 11

Design consideration: a partial summary

St Malo, 13th April 2002 Václav Vrba, Institute of Physics, AS CR 12

Time schedule

• Pre-prototyping using existing masks to evaluate some effects

of:

- high resistive Silicon;

- guard rings, scribe lines, etc.

- #wafers thickness [m]

- 4 SSP Wacker 500

- 3 DSP Topsil 500

- 4 DSP Topsil 300

• Mask design preparation GDS file

• First 10-16 wafers ready for testing

now in process

By end of April 2002

By end of June 2002

St Malo, 13th April 2002 Václav Vrba, Institute of Physics, AS CR 13

Pre-prototypingActive area cca 0.3 cm2

Active area cca 10 cm2

Wafer diameter: 100 mm

Wafer backside all Al metallized

St Malo, 13th April 2002 Václav Vrba, Institute of Physics, AS CR 14

Tests outlines

A) Diode testsa) C-V curves: determination of Vfull-depletion; Vop = Vfull-depletion + 50 V.

b) I-V curves:

- Vbreak-down Vop

- Ileak @ Vop < cca 30 nA/cm2

c) Long term stability tests:

- Ileak @ Vop .

Tile should be rejected if:

- Vbreak-down < Vop

- Ileak > I crit (to be defined).

St Malo, 13th April 2002 Václav Vrba, Institute of Physics, AS CR 15

Electric characterization

St Malo, 13th April 2002 Václav Vrba, Institute of Physics, AS CR 16

Long term current stability on Tile

x 10sx 10s

timetime

Measured @ 150VMeasured @ 150V

St Malo, 13th April 2002 Václav Vrba, Institute of Physics, AS CR 17

Tests outlines

B) Bias resistorsa) shorts

b) breaks

c) outside specifications

C) Capacitance couplingsa) shorts

b) breaks

c) outside specifications

St Malo, 13th April 2002 Václav Vrba, Institute of Physics, AS CR 18

Manual Probestation

St Malo, 13th April 2002 Václav Vrba, Institute of Physics, AS CR 19

Manual Probestation