TimePix / InGridProblems and solutions

Yevgen Bilevych

Amsterdam 28.01.2013

8’’ TimePix wafer

107 single chips

Thickness 725 µm

Surface materials:- Aluminum (aluminum oxide)

- Silicon nitride- Silicon oxide

TimePix chip

14111 m

161

20

m

256 x 256 pixels

20 m

20

m

10 m

CH

IPE

DG

E

Col

umn

0

Col

umn

1

Col

umn

2

Col

umn

3

Col

umn

4

Col

umn

251

Col

umn

252

Col

umn

253

Col

umn

254

Col

umn

255

CH

IPE

DG

E

CHIPEDGE

55

m

55 m

20 m

20

m

28.3 m

48.2

2 m

48.2

2 m

57.7 m

Pixel Row 255

Pixel Row 254

Pixel Row 253

Pixel Row 1

Pixel Row 0

Detector Guard Ring Row

Snake Top Row

Snake Bottom Row

Main technological steps for the formation of structureTimePix / SU-8 / Al grid

4. Formation of structure “support” / grid

1. Formation of protection layer

2. Deposition of spacer material

3. Deposition of the Grid material

Wafer surface quality inspectionW0058 EW5MWBX

Wafer surface quality inspectionW0059 EU5MWDX

Wafer surface quality inspectionW0060 E85MWZX

Wafer surface quality inspectionW0061 E15MVPX

Polyimide mask

Microsystems HD 4100 polyimide - negative tone, solvent developed, photodefinable polyimide

Steps:• Spinning• Baking• Exposition• Development• Silicon nitride deposition• Chemical activation of polyimide• Stripping

Advantage:• Silicon technology compatible

• Perfect alignment• No residuals

Disadvantage:• Temperature sensitive process

• Time consuming process• mechanical scratching of bonding pads

Oxford 80 (PECVD)

PECVD

Plasma enhanced chemical vapor deposition

Silicone oxide or silicone nitride formation

Plasma power max 600 W at 187.5 kHz, max 300 W at 13.56 MHz plasma frequency

Substrate temperature 100 up to 400 °C Layers contain hydrogen

just deposited SixNy

“chemically activated polyimide”

- C

- O

Bisphenol A Novolak epoxy oligomer

SU-8 photoresist composition:

- Gamma Butyrolactone 22-60%

- Up to 10 % Triarylsulfonium / Hexafluoroantimonate Salt (3.3% for SU-8/50)

- Propylene Carbonate 1-5%

- Epoxy Resin 35-75%

SU-8 - epoxy-based negative photoresist

R1

O

CH CH2

+ H+

R1

OH

CH

CH2

++ R1

O

CH CH2

- H+R1

O

CH

CH2

R1

O

CH

CH2

SU-8 crosslinking mechanism

SU-8 layer map

Al layer

Sputtering system Leybold Z660

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25x x x x x x x x x x x x x x x x x x x x x x

DC 50%, no sputter etching, 30 sec – the deposition time for every sputtering run, + cooling delay

Total thickness: ~ 800 nm

deposition of Al layer

Chip

SU-8 photoresist

aluminum

SU-8 column

protection layer

Chip

Pixel pad

Cross-linked SU-8 photoresist

Development of SU-8

1. Acetone2. Acetone:IPA:H2O (1:1:2)3. Acetone:IPA:H2O (1:1:1)4. Acetone:IPA (1:1)5. Microstrip 60016. H2O7. IPA8. Acetone9. Drying in the air

Standard development

Extra cleaning

O2 plasma cleaning

O2 plasma cleaning

O2 plasma cleaning (long time)

IZM-5 started: W0062 (4 m SixNy) and W0063 (8 m SixNy)

Modified InGrid (mInGrid) - started

Summary

W0058 EW5MWBX (W0058 EW5MWBX (4 m SixNy) in process) in process

W0059 W0059 EU5MWDX ( (4 m SixNy) broken) broken

W0060 E85MWZX (W0060 E85MWZX (8 m SixNy) in process) in process

W0061 E15MVPX (W0061 E15MVPX (8 m SixNy)) requires the cleaningcleaning