Photovoltaic Manufacturing: Etching, Texturing, and Cleaning (Solar Cell Manufacturing)

208 Pages·2021·22.874 MB·English

by  Monika Freunek Muller (editor)

Photovoltaic Manufacturing
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Photovoltaic Manufacturing
Etching, Texturing, and Cleaning
Edited by
Monika Freunek Müller
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Library of Congress Cataloging-in-Publication Data
ISBN 978-1-119-24189-8
Cover image: Top figures: RENA Technologies GmbH – BatchTex machine for solar wafer texturing
Bottom row left: Technological Institute of Microelectronics (TiM), University of the
Basque Country (UPV/EHU), Bilbao, Spain
Bottom row right: Fraunhofer Institute for Microstructure of Materials and Systems
IMWS, Research Unit Center for Silicon Photovoltaics CSP, Halle (Saale), Germany
Cover design by Russell Richardson
Set in size of 11pt and Minion Pro by Manila Typesetting Company, Makati, Philippines
Printed in the USA
10 9 8 7 6 5 4 3 2 1
Contents
Preface ix
1 Metal-Assisted Chemical Etching of Silicon: Origin, Mechanism,
and Black Silicon Solar Cell Applications 1
Chenliang Huo, Jiang Wang, Haoxin Fu and Kui-Qing Peng
1.1 Introduction 1
1.2 History and Mechanism of Metal-Assisted
Chemical Etching of Silicon 3
1.2.1 History of Metal-Assisted Chemical Etching of Silicon 3
1.2.2 Mechanism of Metal-Assisted Chemical
Etching of Silicon 7
1.3 Fabrication and Optical Properties of Black Silicon
by MacEtch of Silicon 12
1.3.1 Background of Black Silicon by MacEtch of Silicon 12
1.3.2 Developments on MacEtch Black Silicon
Fabrication Techniques 14
1.4 Photovoltaic Solar Cell Applications of MacEtch Black Silicon 17
1.4.1 Silicon Nanowire/Nanohole-Based MacEtch Black
Silicon for Photovoltaic Solar Cells 17
1.4.2 Alkaline Treatment Modified MacEtch Black Silicon
for Photovoltaic Solar Cells 19
1.4.3 MacEtch Black Silicon for Diamond Sawed mc-Si
Photovoltaic Solar Cells 22
1.4.4 Copper-MacEtch Inverted Pyramid Black Silicon
for Photovoltaic Solar Cells 24
1.5 Concluding Remarks 27
Acknowledgements 29
References 29
v
vi Contents
2 Alkaline Texturing 43
Vanesa Fano, Juan Carlos Jimeno, José Rubén Gutiérrez
and Mª Velia Rodríguez
2.1 Introduction to Alkaline Texturing 43
2.2 Pyramid Formation 46
2.2.1 Main Requirements and Theories 46
2.2.2 Optimizing the Texturing: Shape and Size Aspects 50
2.3 Chemical Mixtures Used in the Alkaline Texturing 51
2.3.1 Overview of Chemistries Used for Alkaline Texturing 51
2.3.2 Most Common Chemistries 52
2.3.3 Other Mixtures 53
2.3.4 Challenges to Develop Alkaline Texturing Recipes 54
2.4 Mechanisms of Alkaline Texturing, Important Parameters
Involved in Alkaline Texturing 54
2.4.1 Influence of Alkaline Concentration 54
2.4.2 Additives 57
2.4.2.1 IPA 58
2.4.2.2 Other Additives 60
2.4.3 Silicates 62
2.4.4 Temperature 65
2.4.5 pH 66
2.4.6 Process Time 66
2.4.7 Agitation 68
2.4.8 Dissolved Gases 71
2.5 Surface Conditioning Prior to Alkaline Texturing 71
2.6 Problems Associated to Alkaline Texturing 73
References 75
3 Advanced Texturing 83
Lixia Yang, Yaoping Liu and Xiaolong Du
3.1 Introduction to Advanced Texturing 83
3.2 History and Definition of Metal-Assisted Chemical Etching 84
3.3 Mechanisms of Metal-Assisted Chemical Etching 85
3.3.1 Reactions of Metal-Assisted Chemical Etching 85
3.3.2 Redox System of Metal-Assisted Chemical Etching 87
3.4 Methods of Metal-Assisted Chemical Etching 90
3.4.1 Two-Step Metal-Assisted Chemical Etching Process 90
3.4.2 One-Step Metal-Assisted Chemical Etching 93
3.5 Copper-Assisted Chemical Etching 99
3.5.1 Copper-Assisted Chemical Etching of c-Si 99
3.5.2 Copper-Assisted Chemical Etching of m-Si 107
Contents vii
3.6 Conclusion 108
References 109
4 Wet Chemical Cleaning for Industrial Application 115
Florian Buchholz, Eckard Wefringhaus and Martin Plettig
4.1 Introduction 116
4.2 Status of Production Technology in Solar Cell
Manufacturing 117
4.3 Wet Chemical Process Technology 119
4.3.1 Tools 119
4.3.2 Etching 123
4.3.3 Cleaning 125
4.3.4 Rinsing and Drying 127
4.3.5 Process Integration 128
4.4 Contamination Management 130
4.4.1 Measurement of Surface Contamination 132
4.4.2 As-Cut Wafer 135
4.4.3 Alkaline Etching 137
4.4.4 Contaminants of Interest and Their Threshold Values 142
4.4.5 Organic Contamination 146
4.4.6 Application: Optimization of HF/O Cleaning Process 147
3
4.5 Cost Considerations 150
4.6 Conclusion 154
Acknowledgments 155
References 155
5 Analytical Techniques for Wet Processing 161
Stefanie Wahl and Sylke Meyer
5.1 Introduction 161
5.1.1 The Importance of Chemical Analysis
on Silicon Surfaces 162
5.1.2 Impact of Surface Contaminations on the Solar
Cell Process 163
5.1.3 Methods for the Determination of Surface
Contaminations 164
5.2 Metal Analysis by ICP-MS 167
5.2.1 Sandwich Method 168
5.2.2 Droplet Scan Method 169
5.2.3 Immersion Method 170
5.2.4 Sequential Etching Methods 171
viii Contents
5.3 Determination of Organic Contaminations 173
5.3.1 SE-TOC 174
5.3.2 Contact Angle Mapping 175
5.3.3 TD-GC-MS 177
Acknowledgments 179
References 179
Index 181