IFR Praha 2004, 16th April 2004 Václav Vrba, Institute of Physics, AS CR 1

Václav Vrba

Institute of Physics, AS CR, Prague

Silicon sensors status

IFR Praha 2004, 16th April 2004 Václav Vrba, Institute of Physics, AS CR 2

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) ion implantation resistors – not considered here.

IFR Praha 2004, 16th April 2004 Václav Vrba, Institute of Physics, AS CR 3

Design consideration: Polysilicon resistors

Bias resistor

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Coupling capacitor

Direct contact on diode – e.g. for testing

Bias lines

IFR Praha 2004, 16th April 2004 Václav Vrba, Institute of Physics, AS CR 4

Design consideration: Polysilicon resistors

IFR Praha 2004, 16th April 2004 Václav Vrba, Institute of Physics, AS CR 5

Design consideration: Punch through resistors

Coupling capacitor

Direct contact on diode – e.g. for testing

Bias resistor

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Bias lines

IFR Praha 2004, 16th April 2004 Václav Vrba, Institute of Physics, AS CR 6

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).

Compatibility of process for variants a) and b) on one wafer? Option a) as a baseline for main sensor tile?

IFR Praha 2004, 16th April 2004 Václav Vrba, Institute of Physics, AS CR 7

Pre-prototyping

IFR Praha 2004, 16th April 2004 Václav Vrba, Institute of Physics, AS CR 8

Tests outlines

A) Diode testsa) I-V curves:

- Vbreak-down Vop

- Ileak @ Vop < cca 30 nA/cm2

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

c) Long term stability tests:

- Ileak @ Vop .

Tile should be rejected if:

- Vbreak-down < Vop

- Ileak > I crit (to be defined).

IFR Praha 2004, 16th April 2004 Václav Vrba, Institute of Physics, AS CR 9

Electric characterization

IFR Praha 2004, 16th April 2004 Václav Vrba, Institute of Physics, AS CR 10

Tests outlines

B) Bias resistorsa) shorts

b) breaks

c) outside specifications

C) Capacitance couplingsa) shorts

b) breaks

c) outside specifications

IFR Praha 2004, 16th April 2004 Václav Vrba, Institute of Physics, AS CR 11

Tests outlines

Basic equipment:- micromanipulators with contact needles;

- I-V: Keithley 487 A;

- C-V: LCR meter HP

IFR Praha 2004, 16th April 2004 Václav Vrba, Institute of Physics, AS CR 12

Probestation