SOLAR SolarInnovativ Thüringen

1

Welcome toSCHOTT Solar

Europe's largest producer ofPV solar electricity components

EFG, ein kostengünstiges Produktionsverfahren für Si-WaferDr. Ingo A. SchwirtlichSolarInnovativ Thüringen25. / 26. Oktober 2006

SOLAR SolarInnovativ Thüringen

2

The SCHOTT Synopsis

��������� ����� ���

� � �� � � � � �*� � � � ��� �� � ��� �� � � � ��� � ��� �� � � � �

� �� �

� �� �� �� � ����

� �� ��� ��� ���� � � � ����

� ��������� � � � �� � � ���� � �� �� �� ���� �

���! �� ��� ��� ��� �� �� � �� � ��

���" # $% % % ���� �� ��� ��� �& # ���� �� ���

SOLAR PHOTOVOLTAICS

3

200119991960 1970 1980

AEG Telefunken

Mobil Tyco Solar Energy

1990

MBB

1994

PST

DASA 50%

NUKEM 50%

Mobil Solar Energy

1996

100% TESSAG

100% NUKEM GmbH

100%RWE Solutions AG

ASE GmbH

ASE Americas Inc.

2002

RWE SCHOTT SolarGmbH

RWE SCHOTTSolar Inc.

Joint VentureRWE SolutionsSCHOTT Glas

RWE Solar GmbH

ASE Americas Inc.

2005

SCHOTTSolar GmbH

1999 2001

SOLAR PHOTOVOLTAICS

4

Alzenau, HeadquartersFully integrated production of wafers, cells and modules

Phototronics(PST) PutzbrunnProduction of thin film modules

SCHOTT Solar GmbH

SCHOTT Solar, Inc.Billerica (MA) USAFully integrated productionof wafers, cells and modules

SCHOTT Solar Inc.Rocklin (CA) USASystem integrationSales of modules andsystems

RWE SCHOTT Solar CRValasske Mezirici, CRProduction of modules

SCHOTT Solar GroupEmployess: ca. 900 world-wideTurnover: ~320 Mio. � in 2006

(forecast)

SCHOTT AG

Subsidiaries 100 %

JenaBuildup of a 30 MW productionline of ASI thin film modules

SOLAR PHOTOVOLTAICS

5

SmartSolarFab® - Alzenau

OEM Zellenfertigung

Heilbronn, D

SOLAR PHOTOVOLTAICS

6

The Value Chain of the SCHOTT Solar Group

Modules Cells Wafer

SOLAR PHOTOVOLTAICS

7

Today's 2005 Value Added Chain forgrid-connected PV Systems(2004 in brackets)

Module

poly Si

BOS

Installation

Cell

Wafer18 %

10 %

25 %

15 %

100 %

15 %

17%

26% (25)

14 % (20)

36% (40)

24% (15)

100 % (100)

Increasingly important is the industry to producemanufacturing equipmentand materials for the whole value chain.

SOLAR PHOTOVOLTAICS

8

70

80

90

100

110

120

130

10 12 14 16 18 20 22 24Efficiency [%]

rela

tive

mo

du

le c

ost

(%

)

EFG = 0.7 mc

CZ/B = 1.35 mc

CZ/Ga = 1.5 mc

mc = 1

Relative Module Manufacturing cost as Function ofEfficiency

SOLAR PHOTOVOLTAICS

9

Advantages of ribbon technologies

0

1

2

3

4

5

ribbonS-Eur.

ribbonM-Eur.

multi S-Eur.

multiM-Eur.

monoS-Eur.

monoM-Eur.

En

erg

y P

ay-B

ack

Tim

e [a

] BOSframelaminate

From: E. Alsema et al. 20th EUPVSEC 2005

SOLAR PHOTOVOLTAICS

10

Estimated reduction of silicon consumption

0

2

4

6

8

10

12

14

16

2005 2010 2015 2020 2025

g S

i/ Wp mono / multi - Si15 % EFG

85 % mono / multi - Si

EFG

Specific feed stock consumption per Wp for different wafer technologies

SOLAR PHOTOVOLTAICS

11

Si - Blockguß

SOLAR PHOTOVOLTAICS

12

Blockguß-Anlage

Deutsche Solar Freiberg

SOLAR PHOTOVOLTAICS

13

Silicium - Block

Abmessungen:

66 cm x 66 cm

Gewicht:

ca. 250 kg

SOLAR PHOTOVOLTAICS

14

Säulenherstellung

Deutsche Solar Freiberg

SOLAR PHOTOVOLTAICS

15

slave drive

main drive

wire web

ingotslurry & abrasive

Drahtsägetechnik

Typische Sägeparameter

Drahtdurchmesser 150 - 250 µm Drahtgeschwindigkeit 5 - 15 m/sÖl- oder Glykol-basierte Slurry SiC Vol. Anteil 30 - 60%

SOLAR PHOTOVOLTAICS

16

EFG-Wafer nach dem Folienziehverfahren

von SCHOTT

Multikristalliner Wafer aus dem

Blockgußverfahren

Multikristalline Silicium - Scheiben

SOLAR PHOTOVOLTAICS

17

SmartSolarFab® - Wafer Production

EFG-Wafer Production (Edge-defined Film-fedGrowth)

SOLAR PHOTOVOLTAICS

18

Productivity Increase and Cost Reduction for c-SiWafers

1990 Actual 1. Step 2. Step 3. Step Long-TermSi-MaterialWafer Thickness [µm] 450 300 200 150 100 50 (-83%)

EFG-Wafer

Tube circumference [dm]9x0,54,5

8x18

8x1,2510

12x1,2515

12x1,518

circle ∅ 1,3m40

Productivity 0,6 1(norm.) 1,2 1,9 2,2 5Material add-on 2 1 1,2 1,7 2 4 (-20%)Personnel 1,5 1 1 1,1 1,2 1,3 (-74%)Depr/Interest 1,5 1 1 1,1 1,2 1,3 (-74%)

2003

SOLAR PHOTOVOLTAICS

19

EFG history� v. Gompertz 1922: Growth of metal wires from a wetted

capillary.

� LaBelle 1971: EFG of sapphire tubes.

� Ciszek 1972: EFG of silicon ribbons.

� Taylor 1981: EFG of polygonal silicon tubes (nonagonswith 50 mm faces).

SOLAR PHOTOVOLTAICS

20

EFG of silicon octagons

� Wald 1985 (Mobil Solar Energy): EFGproduction of silicon octagons with 100 mm faces.

� RWE SCHOTT Solar 2003: EFGproduction of silicon octagons with 125 mmfaces.

SOLAR PHOTOVOLTAICS

21

Edge-defined film-fed growth (EFG)

� Crystal thickness t = f(vs, �T, h, wetting angles)

� Fixed: h, wetting angles

� Control parameters: vs, Tmelt

melt (Tmelt)

die

crystal

vs

h

t

wettingangles

1412 °C

T

�T

SOLAR PHOTOVOLTAICS

22

EFG crystal growth: schematic

Octagonal Die

Molten Silicon

Induction Heater

Silicon Tube

SOLAR PHOTOVOLTAICS

23

125 mm

7 m

125 mm EFG: scales

0.3 mm

SOLAR PHOTOVOLTAICS

24

100 mm and 125 mm octagons

0 10 20 30 cm0 10 20 30 cm

� Increase of throughput by more than25 %.

� No loss of materials quality.

� No increase of wafer thickness.

Increase in productivity by growing 125 mm wide faced octagons instead of 100 mm

SOLAR PHOTOVOLTAICS

25

Cutting of tubes by laser for wafer production

� Several tubes per day and furnaceup to 7 m length.

� Less than 10 % silicon loss at cuttingstep.

� Wafers are immediately processedafter light etch.

SOLAR PHOTOVOLTAICS

26

6x150mm growthFirst 150x150mm samples

100x100 125x125 150 x 150

SOLAR PHOTOVOLTAICS

27

EG wafer properties:carrier lifetime distribution

� As grown lifetimes up to 10 µs.� The distribution mainly correlates to dislocation density variations.

SOLAR PHOTOVOLTAICS

28

Access

Buckling

SOLAR PHOTOVOLTAICS

29

interface

v 45 MPa

-45 MPa

� Non-uniform cooling of edges and facescan result in tube deformation duringgrowth.

� Danger of remaining deformations byresidual stress, creep and plasticdeformation.

tensile

compressive

stress

Advanced process modeling:3D stress and strain

In collaboration of ACCESS e.V., Aachen

SOLAR PHOTOVOLTAICS

30

Latest stage of development: Dodekagons

Oktagon 125 mm Dodekagon 125 mm

SOLAR PHOTOVOLTAICS

31

200 micron thin EFG silicon wafers

SOLAR PHOTOVOLTAICS

32

EFG wafer properties: mechanical strength

0

10

20

30

40

50

60

70

80

90

100

0 100 200 300 400 500 600 700 800 900 1000 1100

mc - Si as grownmc - Si damage etchedEFG as etched

Fracture strength [MPa]

Fai

lure

rat

e [%

]

� Biaxial test: fracture strength of 550 MPa(60% failure rate value) for EFG.

� As-grown surface is free of serious damage.

In collaboration with TU Freiberg

SOLAR PHOTOVOLTAICS

33

Wafer breakage?

Elaborated crack free edge design and stress free volumeis required to minimize breakage of thin wafers.

SOLAR PHOTOVOLTAICS

34

As cut, 4 min Sirtl etched

EFG wafer properties:wafer edge

Standard etched

SOLAR PHOTOVOLTAICS

35

SmartSolarFab® - Cell Production

EFG-Zelle EFG-Zelle MAIN-Zelle MAIN-Zelle100 x 100 mm2 125 x 125 mm2 100 x 100 mm2 125 x 125 mm2

SOLAR PHOTOVOLTAICS

36

Rear side metallisation Front side contact Final inspectionSolder pads Al-contact & Firing

Process sequence for the fabricationof EFG solar cells

Wafer cleaning P - doping Oxide-etching ARC-deposition

SOLAR PHOTOVOLTAICS

37

SmartSolarFab® - Module Production

ASE-275-DG-FT

High Quality Modules

SOLAR SolarInnovativ Thüringen

38

Many thanks for your attention