Advanced wafer processing: Ready for the new PV generation 5th Annual c-Si PVMC Workshop

13.7.2016 – Christoph Eggimann

C B

E

D

A

The new PV generation

SmartWire Connection (SWCT)

TCO layer and wafer thickness

suitable for SmartWire

80% less silver

Higher energy yield

Higher efficiency

Longevity and micro-crack resistant

E

Adapted test metrology

High cap cells

Busbarless cells

DragonBack

PED (chipping)

Single wafer

tracking

Quality & performance

control

B

Diamond wire

Thinner wafer Lower

costs

A

High efficiency

Lower system cost (BOS)

Independent of wafer

thickness

Only 6 process steps

Low CoO

Temperature coefficient

Higher energy yield

Bifacial Higher

energy yield

Heterojunction (HJT)

Texture

a-Si front/rear side

Test & sort

TCO / metal rear contact

Print front side

Curing

C

D

Meyer Burger / 12-2015 2

Enabling wafer technologies

3

Wafer Inspection Slicing

Technology Diamond Wire

Bricking

Technology

Bricking Technology: Integration and

Automation for minimized production cost

4

Manpower-efficiency 1 man operation – fully automated

Space-efficiency 50% less space for equipment and

buffers

Process-efficiency diamond wire / water only / glue free

Material-efficiency 0.42mm kerf silicon savings

PV wafering evolution

Kerf µm 150 150 150 120 <90

Time hrs 8 4 3 3 2

DW Use m/Wf 2 1.2 1 1

Capacity MW 10 15 16 17 30

Diamond Wire

Management System

(DWMS)

2009 2010 2011 2012 2013 2014 2015 2016

Slurry Saws

Newest Generation

Diamond Wire Saw

Pe

rfo

rma

nce

DW Upgrades

Based on Mono 156 x 156 x 0.18 mm Wafers

Dedicated DW Saws

500 MW fab yesterday and today

6 6

Conventional Slurry

Wire Saws

Latest Generation

Diamond Wire Saws

Challenge

DW Wafering Cost of Ownership:

Diamond Wire consumption is the

biggest cost driver

(approx. 50%)

Diamond wire consumption is

influenced by wire wear:

1. CWW = wear from cutting

2. NCWW = wear from winding

Wire Consumption Matters

7

Wafering Cost of Ownership

Wire

Operator

Depreciation

Cutting fluid

WGR

Electricity

Glue

Beam

Spare parts

8

Diamond Wire Management System (DWMS)

Conventional Wire Management

Storage

(Supply) Area

Working

(Winder) Area

How to improve wire performance

9

How does DWMS work?

check base data

10 µm less silicon

>100’000 USD/yr Savings per machine

Challenge: How to capture this

cost saving potential?

What is the Impact of Thinner Wires?

10

90 µm 100 µm

70 µm wire

80 µm

80 µm wire 60 µm wire

Tight Wire Tension Control

Wire Tension Decoupling

Thin wires require improved tension control

11

± 0.5 N

Dedicated Wire Development

Low Inertia Pulleys

Enablers of thin wire slicing Tensio

n Limit

Tight wire

tension control

Diamond Wire

Management

System

Enables thin

wire slicing Conventional

Technology

DWMS

Technology

High performing wire with consistent quality enables higher yields

13

Meyer Burger Diamond Wire

• Coordinated wire, equipment and process

development premium performance

• Manufacturing controls, detection algorithms,

automatic feedback loops improved quality

Cut Nr

TT

V L

ine

(u

m)

Spool 1 Spool 2

Sample TTV Data

Mono 156 / 70 um wire / 1 m/Wf / <2 hr cut time

Fast cut

Mono 156 *) process in development

Mono DW Sample Process

14

0.0

0.5

1.0

1.5

2.0

2.5

95

96

97

98

99

100

0 5 10

Cu

t T

ime

(h

rs)

Wir

e C

on

su

mp

tio

n

(m/w

f)

Sa

w Y

ield

(%

)

Cut Nr

Saw Yield Cut time

Wire consumption

Low wire

usage*

m/Wf hrs

Wire

usage

Cut

time

2 1

3 0.5

Mono fast cut sample results 70 µm wire

80 µm EPW

Multi 156

Multi DW sample process

15

m/Wf hrs

Wire

usage

Cut

time

< 3 1.8 Multi cut sample results 80 µm EPW

0.0

1.0

2.0

3.0

4.0

5.0

95

96

97

98

99

100

0 2 4 6

Cu

t T

ime

(h

rs)

Wir

e C

on

su

mp

tio

n

(m/w

f)

Sa

w Y

ield

(%

)

Cut Nr

Saw Yield Cut time

Wire consumption

TC

O (

US

Dc

/Wf)

Comparing Mono and Multi as-cut wafer total cost of ownership

On per wafer basis, Mono wafer cost on par with Multi

On per Watt basis, mono wafers cost can already be lower than multi

Key drivers are

• Mono vs. Multi brick cost

• Wire cost

• Throughput effects

Assumptions

Mono: 70 um fast cut process; 180 um thickness; 27 USD/kg brick,

Multi: 80 um EPW process; 200 um thickness; 20 USD/kg brick

Multi DW vs. Mono DW Wafer TCO comparison

16

Effect of higher

Mono ingot cost Wire

usage

Effects of higher throughputs

Higher throughputs for Mono driven by faster cutting times and higher number of wafers per mm (thickness, kerf)

Nr of wire saws for Mono reduced compared to Multi

Assumptions

Mono: 70 um fast cut process; 180 um thickness;

Multi: 80 um EPW process; 200 um thickness

Multi DW vs. Mono DW Wire saw capacity comparison

17

0

100

200

300

400

500

600

0 5 10 15 20 25 30

Ca

pa

cit

y (

MW

/yr)

Nr of Machines

Multi Mono Target Capacity

TC

O (

US

Dc

/Wa

fer)

Why is Quality Relevant?

18

Challenge:

Biggest levers for

further TCO

reductions

• Wafer

thickness

• Yield /

Inspection

156 Mono / 180 µm / 70 µm wire

Wafer TCO contributors

Quality is critical to enable further cost-downs

Slicing machine setup

Optimized handling

High quality processes

High quality inspection

Levers to improve slicing quality

19

New TFC Technology

Standard NVCD Technology

How to detect microcracks accurately? Transflection TFC technology

20

Transflection technology increases visibility of microcracks and therefore

minimizes misjudge rate

Challenge edge chips / Perpendicular edge detection

21

• Perpendicular Edge Detection technology

Wafer

edge defect

17

5µ

m

65

µm1

75

µm

90 µm

Near-Term Challenges (1-3 Years)

Please identify/describe your top near-term challenges for the adoption of Advanced Wafering Techniques as it relates to your position in the supply chain

• Improving material utilization via thinner wire diameters (wires, process, machine) as well as thinner wafers

• Providing qualified wafers for next gen PV technologies

• Adoption of diamond wire slicing for Multi crystalline silicon (DW slicing, texturization)

Long-Term Challenges (4+ Years)

Please identify/describe the top long-term challenges for the adoption of Advanced Wafering Techniques as it relates to your position in the supply chain

• High maturity of classical wafering technologies (high throughputs, yields, low costs) may lead to lower capex pool

• Industrializing alternative wafering technologies (kerf free)

• Need for yet higher degrees of automatization, integration and intelligence

Thank you for your attention

Visit us at Intersolar booth 7521 – West Hall

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