Copper Wire Bonding: the Last Frontier of Cost Savings 2012 ASE.pdf · Bernd K Appelt Business...

Bernd K Appelt Business Development ASE (U.S.) Inc. April 11, 2012

Copper Wire Bonding: the Last Frontier of Cost Savings

© 2012 ASE Group. All rights reserved.

Outline

  Fundamental Study

  Reliability Study

  Monitoring Data

  Summary

2

  Introduction

  High Volume Implementation

© 2012 ASE Group. All rights reserved. 3

  Fine wire active development since 2005 in ASE Kaohsiung

  ASE Chung-Li started HVM in Sep 2008

  Followed by ASE Kaohsiung, Shanghai, Malaysia, Korea and Japan.

  HVM covers:

  25/ 23 / 20 / 18 um Cu and Pd/Cu

wire in QFP, SO, QFN, BGA packages.

  wafers from ALL foundries, ALL

nodes, with different structures.

  Overall yield is around 99.85%.

Introduction – ASE Cu wire-bonding history


M units

Introduction – ASE Production Unit Shipment

ASE Group Shipment: More than 7 Billion units up-to-date

5 8 11 24 65 159 201

363 410

575

716

956

1144 1210

1270

1620

1985

2245

0

500

1000

1500

2000

2500

Q3 2008

Q4 Q1 2009

Q2 Q3 Q4 Q1 2010

Q2 Q3 Q4 Q1 2011

Q2 Q3 Q4 Q1 2012

Q2 Q3 Q4

Units: Equivalent to LQFP14x20mm 144L


100 200

500

1500

2400

3000 3800

4500 5400

6100

6700 7000

7500

8300

9400

10000

2% 3%

8%

20%

28%

32%

37%

41%

45% 47%

49% 50%

52% 54%

57% 59%

0%

20%

40%

60%

80%

100%

0

3000

6000

9000

12000

Q1 2009

Q2 Q3 Q4 Q1 2010

Q2 Q3 Q4 Q1 2011

Q2 Q3 Q4 Q1 2012

Q2 Q3 Q4

Cu Wire Bonder Cu Wire Bonder %

Introduction – ASE Cu wire Bonders Quantity


2010 2009

aQFN/ QFN 16%

PQFP 8% LQFP

43% TQFP 8%

PBGA 4%

FBGA 7%

SOIC/PLCC 14%

aQFN/ QFN 27%

QFP 31%

BGA 16%

SOIC 16%

Discrete 10%

QFP 59%

BGA 11%

6

Introduction – Production Volumes by Package Types

aQFN/ QFN 35%

QFP 23%

BGA 14%

SOIC 20%

Discrete 8%

2011


40/45 nm 1%

60/65 nm 7%

90/80 nm 14%

0.13 um 18%

0.18 um 36%

0.25um 3%

0.35 um 9%

>= 0.4um 12%

2010

65/60 nm 2%

90/80 nm 10%

0.13um 22%

0.18 um 37%

0.25 um 5%

0.35 um 10%

>=0.4um 14%

2009

7

Introduction – Production Volumes by Wafer Nodes

40/45 nm 2%

60/65 nm 11%

80/90 nm 14%

0.13 um 13% 0.18

um 42%

0.25 um 8%

0.35 um 6%

0.4 um 4%

2011


Computing

20%

Consummer 48%

Comm (Cell

Phone) 24%

Auto 0.2%

Industrial 8%

2010

Computing 15%

Consumer 54%

Comm 21%

Industrial 10%

2009

8

Introduction – Production Volumes by Applications

Computing 20%

Consumer 51%

Comm 24%

Auto 0.4%

Industrial 4%

2011


130nm

90 nm

65 /60nm

45/40 nm 32/28 nm

22/20 nm

2012 2011

60/50um

45/40um 40/35um 35/30um ?

50/45um

(BBP / BPO) Au wire

1.2 Au wire

1.0 Au wire

0.9 Au wire

0.8 Au wire 0.7

Au wire 0.6 Au wire

0.5

Cu wire 0.8~1.0 Cu wire

0.7 Cu wire

0.6

Cu wire 1.0~1.2

0.7 mil 17%

0.8 mil 52%

0.9 mil 12%

1.0 mil 16%

1.2 mil 2%

>2 mil 1% Wire Diameter Trend

9

Introduction – Production Volumes by Wire Diameters

2013

0.7mil 22%

0.8mil 52%

0.9mil 10%

1.0mil 13%

1.2mil 2%

>1.2mil 1% 2010 2011

2011


Outline



  Monitor Data

  Summary 10

  Introduction



Cons: 1. Surface Oxidation

1. Inert gas requirement 2. Hardness Impact Al Pad 3. EFO kit requirement

Pros:

1. Lower Material Cost

2. Lower Electrical resistivity

3. Better Thermal Conductivity

4. Better Mechanical Properties

5. Slower IMC Growth.

11

Bonding Wire Au Cu

Atomic weight (g/mol) 197 64

Density (g/cm-‐3) 19.3 8.94

MelDng point 1066 °C 1085°C

Boiling point 2856 °C, 2562 °C

Electrical resisDvity (nΩ·∙m -‐20 °C-‐ )

22.1 16.8

Thermal conducDvity (W·∙m−1·∙K−1 -‐300 K-‐ )

318 401

Young's modulus (Gpa)

79 110–128

Vickers hardness (Mpa)

216 369

Cu Wire vs Au Wire : Raw Material Properties

Fundamental Study


EFO Kit

Good FAB

(a) Control EFO process.

(b) Forming gas rate.

Void Unstable FAB Asymmetry

EFO kit with Forming gas:

For Stable / Symmetric FAB :

12

Process Control: Fundamental Study


Source: Johnny Yeung, Challenges for Copper Wire Bonding, KnS , 2008

Cu Wire Bonding

Au Wire Bonding Cu Wire vs Au Wire : Hardness

Hardness

Au Ball

Cu Ball

Al Splash

13

Fundamental Study


Cratering / Cracking Test

Remained Al thickness: 277nm

Al thickness remaining : > 100nm (min)

Al thickness remaining should > 100nm.

Cratering Crack

14



 High energy transformation capillary.  Parameter optimization.  Ball shape control.  Ball shear inspection.

CUP Design & LowK Wafer

• Fine Pitch • Small Pad opening • Circuit Under Pad • Cu / low K

Defect photos



Top Al Metal

(Top -1) Al Metal

CUP Layer

P1

USG

Cu wire

Al wafer design

Cu wire

Al Cap TOP Cu Metal

(Top – 1) Cu Metal

CUP Layer

P1

P2

USG or FSG

Cu wafer design

•  The top 2 metal layers (Top and Top-1) can not be circuit layers

•  The top 2 metal layers (Top and Top-1) must be solid layer and

must be larger than bond pad

Design Guideline : CUP Bonding

16

Fundamental Study


Reliability Test Cu-Al IMC Inspection

17


2004 M. Li, C. Li, F. Wang, D. Luo, and W. Zhang, Thermodynamic,Assessment of the Al- Au System, J. Alloys Compd. , 1991Oka1: H. Okamoto, Al-Au (Aluminum- Gold), J. Phase Equilib., Vol 12 (No. 1), 1991, p 114-115

Reliability Test

18


“ Cl- ” ions reacts with IMC & creates “Al2O3” with high resistivity,

The mechanism for open failure in biased HAST test

Studies and Learning

Reliability Test Improvement

Mold Compound Cl ions - low ppm required

Cl-

Cl-

Cl-

Cl- Cl-

Inside Mold Compound

Cu Wire

Cl-

Cl- Cl-

Cl-


Cu Wire

Al2O3 Cl-

Cl-

Cl-


Cu Wire

Al2O3 Al2O3 Al2O3 Al2O3

Cu9Al4+6HCl+3O2+nH2O! 2AlCl3+2Al(OH)3* +9Cu+nH2O


Outline



  Monitor Data

  Summary 20

  Introduction



Monitoring Data


Outline



  Monitor Data

  Summary 22

  Introduction



Cu Wire Process/Package Qualifica=on (APQP)

Product Design & Development Qualifica=on Pre-‐produc=on

Monitoring HVM RFQ

3. Package / Process Qualifica=on

2. Process / Package Development

1. Design & Feasibility Study

1. Design Rules review 2. Products/Processes data

Domain: -‐ Wafer Tech & Bond Pad Structure, BOMs, Package

construc=on -‐ device groupings

3. Electrical & Stress Modeling

1. Machine Calibra=on 2. Cu Wire Process DOE & Window

Valida=on 3. Pre-‐qualificaDon & REL assessment

1. Machine C & C 2. Qualifica=on POR 3. Package REL & Extended REL

1. Machine C & C 2. Pre-‐produc=on

POR

1. Machine C & C

2. REL MON

Cu Wire Product/Process Qualifica=on Flow Overview

Bonders Calibration & Correlation Process Recipe Potability

Process Design & Development


Device Groupings & Data Base

Wirebonder Calibra=on

& Correla=on

Wire Diameter

> 1 mil Diameter

< 0.9mil Diameter

-‐ BPO -‐ Wire Length -‐ MulD-‐Ders

CUP / Non CUP

Via Structure

Under-‐layer Metal Stacking

Wafer Nodes

Bondpad Structure

20um 25um

BOM Selec=on, Package StressModelling

(bHAST solu=on)

Film Materials

Al Bond Pad Cu

Silicon

Al

Mold Compound Cu Ball

Film Materials

0.45um Al thickness


WB Parameters &

Control

WB WIP Staging Time Control

Cu Wire Material Controls

Gas Flow Rate control

Set-‐up/Conversion buy-‐off

•  Free Air Ball(FAB) – wire type change

•  WB Quality Characteris=cs

•  Copper wire bonder MTMV

•  Regular calibra=on & correla=on

•  Forming Gas (Bare copper wire)

•  N2 Gas (Pd coated wire only)

•  Locked and can be adjusted within controlled range

•  1st Bond and 2nd Bond-‐ USG and Bond Force

•  EFO Fire Time-‐ Control the size of FAB

•  System control through MES-‐system

Integrated Controls

•  Plasma to WB

•  WB processing =me

Cu Wire Bond Process Control

Wirebond Process/Quality/Material Controls

Cu-‐Wire Package In High Volume Manufacturing


More Challenges to be addressed

 Advanced Nodes  Legacy Products  Automotive & Advanced Network

Systems  New Package Technologies  Collaborative Research with

Universities, suppliers, and research institutes


Outline



  Monitor Data

  Summary 27

  Introduction



Cu Wire Technology

2009 2010 2011 2012

Cu wafer

Wafer Node 0.18um/0.15um

Wafer Node (LK) 0.13um/90nm/65nm

Wafer Node (ELK) 45nm/40nm

Al wafer CUP wafer

BPP62um/BPO55um BPP52um/BPO45um BPP45um/BPO40um BPP40um/BPO35um

Wafer Node (ELK) 28nm

Tri-tier/Quar-tier

NiAu/NiPd pad

L/F PKG Substrate PKG

Stack die

Low loop

FOW

Pad to pad

In-line/Staggered

Waf

er T

ech.

Pack

age

Tech

.


New wafer technology overview

  For BGA PKG: - Au wire MP on 40nm wafer, available on 28nm wafer technology - Cu wire MP on 40nm wafer, Qual lot build on 28nm wafer, expect Qual finish on Y2012Q1

  For QFP PKG: - Au wire MP on 40nm wafer, under plan on 28nm wafer - Cu wire MP on 40nm wafer, under plan on 28nm wafer

PKG Available 2011 2012

BGA

QFP

Production

0.13 um/ 90nm /65nm/ 40nm

0.13 um/ 90nm /65nm/ 40nm

40nm

28nm Au wire

Cu wire

Au wire

Cu wire

40nm

0.13 um/ 90nm /65nm/ 40nm 40nm

2013

20 nm ELK

28 nm ELK 20 nm ELK 0.13 um/ 90nm /65nm/ 40nm

28 nm ELK

28 nm ELK


Summary

  Fine pitch Cu wire-bonding ramped successfully into high volume production in all sites .

  Close collaboration and partnership with equipment and materials suppliers.

  Devices from advanced wafer nodes from different foundries in broad spectrum of packages

  ASE has 6 years experience in Cu wire-bonding, total shipment will exceeded 7 billion units at end of 2011

  Reliability demonstrated to exceeded up to 6X standard JEDEC testing and is continuing.

30


Thank You

www.aseglobal.com

Copper Wire Bonding: the Last Frontier of Cost Savings 2012 ASE.pdf · Bernd K Appelt Business...

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Transcript of Copper Wire Bonding: the Last Frontier of Cost Savings 2012 ASE.pdf · Bernd K Appelt Business...