Bump Bonding of PILATUS Multichip Modules

Workshop on Bonding and Die Attach Technologies, 11-12 June 2003 CERN

Ch. Brönnimann, SLS Detector Group

Bump Bonding of PILATUS Multichip ModulesChristian Brönnimann

Swiss Light Source SLS5232 Villigen-PSI

Pixel Apparatus for the SLS

PILATUS Outline of the talk:

1. Project and component description

2. PSI bump bonding process

3. What can go wrong



Swiss Light Source: The Beamlines

10m

LINAC (100 MeV)

Booster (2.4 GeV)

Storage Ring (2.4 GeV, 288 m)

Undulators

DiagnosticsXA

S

1L

2S

3M

4S

5L

6S7M

8S

9L

10S

11M

12S

IRVUV

MYTHENDetector

PILATUSDetector

Surfaces/Interfaces Spectroscopy

Surfaces/Interfaces Microscopy

ProteinCrystallography

Material Science



PILATUS DetectorFinal Size: 40 x 40 cm2 (0.16m2)

2000 x 2000 pixels

Modular detector -> dead area ~6%Frame rate: >10Hz

High duty cycle: <6% (Tro~6ms)

6x3 modules (2003)

Sensor

RO-Chips

Module Control Board(RO-electronics) High Density

Interconnect (HDI)

Al-Support

1 Module: (35 x 80 mm2)



Module Geometry

+

(0.7,0.7)(-0.2,-1.285)

(1.85,-1.18)

(0,0)

+(79.422,34.069)

(80.122,34.769)(79.620,35.355)

18.2

6m

m0.

60m

m

35.4

8m

m36

.64

mm

37.6

5m

m38

.60

mm

6.24 mm

9.90 mm

79.77 mm

80.80 mm81.20 mm

STEP: 9.982

Active Area: X (8*44+7*2)*0.217=79.422 Y(2*78+1)*0.217=34.069


SLS06 Chip: Specification

Radiation tolerant DMILL technologyAvailable since Mai 20016”-wafersChip size : 20 x 10 mm2, (44 x 78 pixels)64 chips/ wafer Yield: 30% Low noise analog block (ENC tot = 70 e-)Shaping time tsh = 100 ns -> 1MHzIndividual threshold adjustment Low overall threshold variation (σ < 100e-)15 bit pseudo random counter (Semi static)chip size 44 x 78 pixels (20 x 10 mm2)Each pixel is XY-addressableRead-out time: 6.7ms (at 10 MHz)


Sensors

• Colibrys SA, Neuchatel, Switzerland• 4” wafer, single sided process• Si-N-Material, 6-10kΩcm, d=0.3mm• Backside: n+ implant, aluminized• Vdep ~+30 V, Vbias ~+90V• UBM deposition Ti/W, Au



Indium Bump Bonding (PSI)Developed for CMS by R. Horisberger, S. Streuli, F. Glaus

Aluminum - Chip Pads

Under Bump Metal

Foundry or LNS (PSI)

Photoresist for lift off

LMN (PSI)

Indium

Reflow Bump diameter 18 µm

Lift-off

Single Chips

10mm Wafers

15mm Wafers



Bump bonding (cont)Sensors:- Wafers with Indium- Dicing- Reflow

Chips:- Wafers with UBM+Indium- Dicing- Testing of the chips

-Bump pressing-Reflow of bump bonded assembly

PILATUS Module


PILATUS ModuleModule Data• Active Area: 79.6 x 35.3 mm2

(continuously sensitive)

• 157 x 366 = 57462 pixels

• 16 chips (radiation hard)

• Pixel size 0.217x0.217 mm2

• Readout-time: 5 ms

• Energy Range:Eγ >6 keV

• Minimum Threshold 3 keV

• Threshold adjust per pixel

• Threshold RMS 6% of threshold

• Rate: 1MHz/pixel

• 15-bit counter/pixel

• single photon counting, no readout noise



Indium Evaporation

• 4,6,8” wafers

• single wafer evaporation

• 4 wafers/day



Sensor Liftoff



Sensor after Reflow



Sensor after Reflow



Sensor after Reflow



SLS06 Chip: Testing

• Manual Probestation• Chips are tested after dicing

Probecard

6” CMOS Wafer (diced)



Bump bonder



Geometrical verification

Deviation from x=341,y=0

-4.0

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14

gap nr

[um

] dxdy

(341,0)

Sensor

Chips



Pull tester, removing of chips

Pull Tests:

- Good chips hold > 300 g (~0.1 g / bump)

- Pull each chip with 75 g

- Miss-positioned chips hold 0 g



• Module with 54912 bumps

•55Fe (6keV) illumination

• Result corrected by a map of digital+analog defects+ high threshold: 3293 pixels (5.9%)

• 217 pixels give no response for Fe55 (0.39%)

• If test is done with 90Sr, < 50 bad pixels

Bad bond map (Mod 9)

Eric F. EikenberrySLS Detector Group

PILATUS Detector at Spring-8 BL38B1

Lysozyme1° rotation10 s exposure



Modul Nr Date Chips Remarks Modul Nr Date Chips Remarks

Wafno Electrically Defect Wafno Defects

Module 1 Aug 01 4 2 chips D1 Jan 03 15,17 0 chips 1 bad chip W15

Module 2 Aug 01 1 2 chips D2 Jan 03 15,17 0 chips 7 bad chips W15

Module 3 Oct 01 3 4 chips D3 Jun 03 18 ? ?

HDI 1 Oct 01 2 2 chips D4

HDI 2 Oct 01 5 2 chips D5

Module 4 Nov 01 6 1 chip Bank D6

Module 5 Nov 01 3,5,10 1 chip Bank D7

Module 6 Feb 02 10,11 0 chips Bank D8

Module 7 Mar 02 10 Unusable Sensor overetched D9

Module 8 Jun 02 12 0 chips Overheated D10

Module 9 Jan 03 13,14 0 chips good D11

Module 10 Jan 03 14,15 0 chips 3 bad chips W15 D12

Module 11 Jan 03 17,18,20,21,22 0 chips good D13

Module 12 Jun 03 18 0 chips good D14

Module construction history



What can go wrong:Module 7: Scanning electron microscope pictures

• Passivation topology

• Passivation attacked by UBM etching

• lift-off with MAR 404 etched Al away



What can go wrong:Modules 10,D1,D2: Problems with Chips from wafer 15

Scanning electron microscope analysis with EDX, Auger electron spectroscopy (surface sensitive)

0 1 2 3 4 5 6

-200

20406080

100120140160180200220240260280

3.3/4.40.6/3.4

24/14

TiSi

Al

C20A_intens: Pad2 C20B_intens: Pad2 (im Kratzer)

#X-R

ays

Energy [keV]0 1 2 3 4 5 6

0

50

100

150

2.7/2.60.6/1.1

0.9/1.78.5/0.9

0.09/0.070.17/0.21

8/40.5/13

1.7/1.360.6/3.6

AuTi

Al

Si

In

C17BUMB1: Pad C15BUMP1: Pad C15BUMB2: Indium C15BUMB3: Ring

#X-R

ays

Energy [keV]

C15bumb1C17bumb1

C15bump2

C15bump3



Summary and Outlook

• PSI Bump-Bonding Process based on a lift-off process with Indium

• Processing of the 4 and 6”-wafers is done professionally in the clean-room of the LMN at PSI

• Bump-bonding of big multi-chip modules is working

• Problems at the processing level are solved: Tools like SEMs, EDX, AES are very helpful for debugging

• Visual and mechanical tests are very efficient and do not harm the modules (as opposed to electrical tests)

• Rework on mis-positioned chips is routinely done

• Plan for this year: Fabricate 20 more modules of this type

• Plan for the future: Upgrade clean-room for 8”-processing,

• Ev. move bump-bonding equipment to clean room.



Many thanks to my colleagues

Christoph Bühler

Eric Eikenberry

Fredi Glaus

Michael Horisberger

Roland Horisberger

Gregor Hülsen

Markus Naef

Hermann Rickert

Tilman Rohe

Bernd Schmidt

Silvan Streuli

Documents

Bump Bonding of PILATUS Multichip Modules