Kohli / Mittal Developments in Surface Contamination and Cleaning, Volume 8

Cleaning Techniques
1. Auflage 2014
ISBN: 978-0-323-31271-4
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)

E-Book, Englisch, 234 Seiten

As device sizes in the semiconductor industries shrink, devices become more vulnerable to smaller contaminant particles, and most conventional cleaning techniques employed in the industry are not effective at smaller scales. The book series Developments in Surface Contamination and Cleaning as a whole provides an excellent source of information on these alternative cleaning techniques as well as methods for characterization and validation of surface contamination. Each volume has a particular topical focus, covering the key techniques and recent developments in the area.Several novel wet and dry surface cleaning methods are addressed in this Volume. Many of these methods have not been reviewed previously, or the previous reviews are dated. These methods are finding increasing commercial application and the information in this book will be of high value to the reader. Edited by the leading experts in small-scale particle surface contamination, cleaning and cleaning control these books will be an invaluable reference for researchers and engineers in R&D, manufacturing, quality control and procurement specification situated in a multitude of industries such as: aerospace, automotive, biomedical, defense, energy, manufacturing, microelectronics, optics and xerography. - Provides a state-of-the-art survey and best-practice guidance for scientists and engineers engaged in surface cleaning or handling the consequences of surface contamination - Addresses the continuing trends of shrinking device size and contamination vulnerability in a range of industries, spearheaded by the semiconductor industry and others - Covers novel wet and dry surface cleaning methods of increasing commercial importance

Autoren/Hrsg.

Kohli, Rajiv

Mittal, Kashmiri L.

Inhaltsverzeichnis

1;Front Cover;1
2;Developments in Surface Contamination and Cleaning: Cleaning Techniques;4
3;Copyright;5
4;Contents;6
5;Contributors;10
6;Preface;12
7;About the Editors;16
8;Chapter 1: How Green and Does it Clean: Methodologies for Assessing Cleaning Products for Safety and Performance;18
8.1;1. Background;19
8.2;2. Environmental Concerns;20
8.3;3. Green Cleaning;20
8.4;4. Regulatory Aspects;23
8.5;5. Product Selection;25
8.6;6. Green Assessment-What Makes a Product Green?;26
8.6.1;6.1. Pollution Prevention Options Assessment Tool (P2OASys);27
8.6.2;6.2. Green Screen;28
8.6.2.1;6.2.1. Human Health Group I;33
8.6.2.2;6.2.2. Human Health Group II and II;33
8.6.2.3;6.2.3. Environmental Toxicity and Fate;33
8.6.2.4;6.2.4. Physical Hazards;33
8.6.2.5;6.2.5. Green Screen Process Steps;34
8.6.3;6.3. Environmental Protection Agency Design for the Environment;37
8.6.3.1;6.3.1. Acute Mammalian Toxicity;38
8.6.3.2;6.3.2. Carcinogenicity;38
8.6.3.3;6.3.3. Genetic Toxicity;38
8.6.3.4;6.3.4. Neurotoxicity;38
8.6.3.5;6.3.5. Repeated Dose Toxicity;38
8.6.3.6;6.3.6. Reproductive and Developmental Toxicity;38
8.6.3.7;6.3.7. Respiratory Sensitization;39
8.6.3.8;6.3.8. Skin Sensitization;39
8.6.3.9;6.3.9. Environmental Toxicity and Fate;39
8.6.3.10;6.3.10. Eutrophication;39
8.6.4;6.4. Green Seal Environmental Standard for Cleaning and Degreasing Agents (GS 34);47
8.6.4.1;6.4.1. Toxic Compounds;47
8.6.4.2;6.4.2. Carcinogens and Reproductive Toxins;47
8.6.4.3;6.4.3. Corrosivity and Causticity;47
8.6.4.4;6.4.4. Skin and Eye Irritation;47
8.6.4.5;6.4.5. Flammability and Ignitability;47
8.6.4.6;6.4.6. VOC Content;48
8.6.4.7;6.4.7. Ozone Depletion;48
8.6.4.8;6.4.8. Toxicity to Aquatic Life;48
8.6.4.9;6.4.9. Aquatic Biodegradability;48
8.6.4.10;6.4.10. Eutrophication;48
8.6.4.11;6.4.11. Disposal;48
8.6.4.12;6.4.12. Animal Testing;48
8.6.5;6.5. Quick Guide for Tools;48
8.7;7. Performance Testing/Efficacy Evaluation;51
8.7.1;7.1. Basic Testing Process;53
8.7.1.1;7.1.1. Phase I Product Selection;53
8.7.1.2;7.1.2. Phase II Temperature and Concentration Studies;53
8.7.1.3;7.1.3. Phase III Mechanical Energy Studies;54
8.7.1.4;7.1.4. Phase IV Actual Product Cleaning Studies;55
8.7.1.5;7.1.5. Phase V Pilot Plant/Scale-Up Feasibility Studies;55
8.7.2;7.2. Case Studies;57
8.7.2.1;7.2.1. Case Study1-Shedding Some Light on Laboratory Versus Field Practices [22];57
8.7.2.2;7.2.2. Case Study2-Thinking Outside the Cable Box-Wire & Cable Company Uses Floor Stripper on Cables [23];68
8.7.2.3;7.2.3. Case Study3-A Gear Company Decides to Go all the ``Wayqueous´´-Greasing the Wheels for Regulatory Change and Resis...;77
8.7.3;7.3. Case Study Summary;80
8.8;8. Summary;80
8.9;Appendix A. Contact Information for Cleaning Products and Suppliers;81
8.10;Appendix B. Contact Information for Soils and Contaminants and Suppliers;84
8.11;References;85
9;Chapter 2: UV-Ozone Cleaning for Removal of Surface Contaminants;88
9.1;1. Introduction;88
9.2;2. Surface Contamination and Cleanliness Levels;89
9.3;3. Principles of UV-Ozone Cleaning;90
9.4;4. Process Variables;95
9.4.1;4.1. UV Sources;95
9.4.2;4.2. Distance from the Source;95
9.4.3;4.3. Precleaning;95
9.4.4;4.4. Types of Contaminants;96
9.4.5;4.5. Types of Substrates;96
9.5;5. Cleaning Systems;96
9.5.1;5.1. Costs;102
9.5.1.1;5.1.1. Examples of Cost Savings;102
9.6;6. Advantages and Disadvantages of UV-Ozone Cleaning;103
9.6.1;6.1. Advantages;103
9.6.2;6.2. Disadvantages;104
9.7;7. Applications;105
9.7.1;7.1. Semiconductor and Electronics Parts;106
9.7.2;7.2. Cleaning of Reference Masses;107
9.7.3;7.3. Solar Wind Sample Collectors;107
9.7.4;7.4. Metal Surfaces;107
9.7.5;7.5. Glass and Optical Materials;108
9.7.6;7.6. Probe Tips;109
9.7.7;7.7. Decontamination of Incubator Cabinets;109
9.7.8;7.8. Preparation of Samples for Trace Element Analysis;110
9.7.9;7.9. Polymer Surfaces;110
9.7.10;7.10. Textiles and Fabrics;111
9.8;8. Summary;111
9.9;References;85
10;Chapter 3: Use of Water Ice for Removal of Surface Contaminants;122
10.1;1. Introduction;122
10.2;2. Surface Contamination and Surface Cleanliness Levels;123
10.3;3. Theoretical Considerations;133
10.3.1;3.1. Phase Behavior;133
10.3.2;3.2. Mechanical Properties;134
10.3.3;3.3. Mechanism of Ice Blasting;136
10.4;4. Description of the Process;138
10.5;5. Cleaning Systems;139
10.5.1;5.1. Abrasive Medium Addition;143
10.6;6. Cost Considerations;143
10.7;7. Advantages and Disadvantages;145
10.7.1;7.1. Advantages;145
10.7.2;7.2. Disadvantages;145
10.8;8. Applications;146
10.8.1;8.1. Semiconductor Wafer Cleaning;146
10.8.2;8.2. Electronics and Photonics Applications;147
10.8.3;8.3. Automotive Components;147
10.8.4;8.4. Nuclear Applications;148
10.8.5;8.5. Deburring of Components;150
10.8.6;8.6. Recycling and Recovery;151
10.8.7;8.7. Facility Decommissioning;151
10.8.8;8.8. Restoration of Historic Building;151
10.8.9;8.9. Oil Field Equipment Cleaning;152
10.8.10;8.10. Cleaning Pipes;153
10.9;9. Summary and Conclusions;153
10.10;References;85
11;Chapter 4: Post-CMP Cleaning;162
11.1;1. Introduction;162
11.2;2. Forces on Particulate Contaminants in a Post-CMP Cleaning Process;164
11.2.1;2.1. van der Waals Forces;164
11.2.2;2.2. Double-Layer Interactions;167
11.3;3. Types of Post-CMP Cleaning Processes;168
11.3.1;3.1. Batch Cleaning;168
11.3.2;3.2. Single Wafer Cleaning;173
11.3.2.1;3.2.1. Brush Cleaning;173
11.4;4. Megasonic Cleaning;180
11.5;5. Cleaning Chemistries;186
11.5.1;5.1. Silicon Dioxide Post-CMP Cleaning;186
11.5.2;5.2. Tungsten Post-CMP Cleaning;191
11.5.3;5.3. Copper Post-CMP Cleaning;192
11.6;6. Summary;197
11.7;References;85
12;Chapter 5: A Brief Review of the Cleaning Process for Electronic Device Fabrication;202
12.1;1. Introduction;203
12.2;2. Cleaning of Inorganic Contamination;203
12.2.1;2.1. Neutral Particles;203
12.2.2;2.2. Ionically Bonded Particles;204
12.2.2.1;2.2.1. Ionic SRP;204
12.2.2.2;2.2.2. Ionic Trapping Process;206
12.2.3;2.3. Covalently Bonded Particles;207
12.2.3.1;2.3.1. Foreign Bonded Particles;207
12.2.3.2;2.3.2. Native Bonded Particles;208
12.2.3.2.1;2.3.2.1. Cleaning Solution Containing a Component with a Low Dissociation Constant;211
12.2.3.2.2;2.3.2.2. Stream Cleaning Solution;212
12.2.3.2.3;2.3.2.3. Spray Cleaning;213
12.2.4;2.4. Zeta Potential;213
12.2.4.1;2.4.1. Factors Affecting the Zeta Potential;215
12.2.4.1.1;2.4.1.1. pH;215
12.2.4.1.2;2.4.1.2. Effect of Concentration;215
12.2.4.2;2.4.2. Measurement of the Zeta Potential;216
12.3;3. Cleaning of Organic Contaminants;217
12.4;4. Effects of Surfactants in Cleaning Solutions;218
12.5;5. Wet Cleaning for Removing Trace Metals after Etching Process;220
12.5.1;5.1. Aluminum;221
12.5.2;5.2. Gold;222
12.5.3;5.3. Chromium;222
12.5.4;5.4. Indium Tin Oxide;222
12.5.5;5.5. Titanium Tungsten;222
12.5.6;5.6. Copper;222
12.5.7;5.7. Nickel;223
12.5.8;5.8. Gallium Arsenide;223
12.6;6. Silicon Product Wet Etching Process;223
12.6.1;6.1. Silica Isotropic and Anistropic Etching;224
12.6.2;6.2. Silicon Isotropic and Anisotropic Etching Process;224
12.6.3;6.3. Silicon Nitride;226
12.6.4;6.4. Dry Etching Process;226
12.6.5;6.5. Advantages and Disadvantages of Dry Versus Wet Etching;227
12.7;7. Summary and Conclusions;227
12.8;References;85
13;Index;230

Leseproben

Chapter 2 UV-Ozone Cleaning for Removal of Surface Contaminants
Rajiv Kohli    The Aerospace Corporation, Houston, Texas, USA Abstract
An overview of the ultraviolet-ozone (UV-O3) method for removal of surface contaminants is provided. UV-O3 is an effective method for removing a variety of contaminants from various surfaces. It is a simple-to-use dry process which is inexpensive to set up and operate. It can produce near-atomically clean surfaces, in air or in a vacuum system, at ambient temperatures. Recent applications of UV-O3 cleaning for removal of surface contaminants are discussed. Keywords Ultraviolet (UV) Ozone Cleaning Surface contaminants Mercury lamp Xenon excimer lamp Reference kilogram masses Chapter Contents 1 Introduction   71 2 Surface Contamination and Cleanliness Levels   72 3 Principles of UV-Ozone Cleaning   73 4 Process Variables   78 4.1 UV Sources   78 4.2 Distance from the Source   78 4.3 Precleaning   78 4.4 Types of Contaminants   79 4.5 Types of Substrates   79 5 Cleaning Systems   79 5.1 Costs   85 5.1.1 Examples of Cost Savings   85 6 Advantages and Disadvantages of UV-Ozone Cleaning   86 6.1 Advantages   86 6.2 Disadvantages   87 7 Applications   88 7.1 Semiconductor and Electronics Parts   89 7.2 Cleaning of Reference Masses   90 7.3 Solar Wind Sample Collectors   90 7.4 Metal Surfaces   90 7.5 Glass and Optical Materials   91 7.6 Probe Tips   92 7.7 Decontamination of Incubator Cabinets   92 7.8 Preparation of Samples for Trace Element Analysis   93 7.9 Polymer Surfaces   93 7.10 Textiles and Fabrics   94 8 Summary   94 Acknowledgment   94 Disclaimer   94 References   95 Acknowledgment
The author would like to thank the members of the STI Library at the Johnson Space Center for help with locating obscure reference articles. 1 Introduction
Removal of surface contaminants is essential to all processes where the surface must be modified in some manner, such as deposition of thin films, bonding, or surface patterning. Both organic and inorganic contaminants can cause unreliable bonding or even prevent continuous bonding. Wet and dry cleaning are well-established processes for removal of surface contaminants in a variety of industrial applications. Many of the conventional solvents used for wet cleaning, such as hydrochlorofluorocarbons (HCFCs), are considered detrimental to the environment and are increasingly subject to regulations for reduction in their use and eventual phase out [1–3]. As a result, there is a continuing effort to find alternate cleaning methods to replace solvent cleaning. Several dry cleaning methods have been developed and have been commercialized using lasers, microabrasives, plasma, ultraviolet (UV)-ozone (UV-O3), solid gas pellets or soft snow (CO2, Ar-N2), electrostatic charge, water ice crystals, micro- and nanoparticle beams, and high-velocity air jets [4–6]. UV-O3 is a highly effective method for removal of organic surface contaminants to near-atomic levels. Compared to other dry surface treatment techniques, UV-O3 treatment has the distinctive advantages that it can be conducted under atmospheric pressure, and hence the equipment and running costs are relatively low. Gas plasma (oxygen, hydrogen plasmas), in particular, can have a significant sputtering effect as it contains a complex mixture of protons, electrons, ions, radicals, and excited species with high kinetic energy. In contrast, UV-O3 cleaning is milder than the oxygen plasma due to the absence of high kinetic energy particles. This means that the UV-O3 cleaning method can complement conventional cleaning techniques based on oxygen or hydrogen plasma for a variety of applications. UV-O3 can be used for removal of surface contaminants and for modification of the surface. Several reviews of the technology have been published [7–12]. The intent of this chapter is to provide an overview and discuss recent applications of UV-O3 cleaning for removal of surface contaminants. 2 Surface Contamination and Cleanliness Levels
The most common categories of surface contaminants include particles, thin film or molecular contamination that can be organic or inorganic, ionic contamination, and microbial contamination [13]. Other contaminant categories include metals, toxic and hazardous chemicals, radioactive materials, and biological substances, which are identified for surfaces employed in specific industries. Surface contamination can be in many forms and may be present in a variety of states on the surface. Common contamination sources can include machining oils and greases, hydraulic and cleaning fluids, adhesives, waxes, human contamination, and particulates. In addition, a whole host of other chemical contaminants from a variety of sources may soil a surface. Typical cleaning specifications are based on the amount of specific or characteristic contaminant remaining on the surface after it has been cleaned. Cleanliness levels in precision technology applications are typically specified for particles by size (in the micrometer (µm) size range) and number of particles, as well as for hydrocarbon contamination represented by nonvolatile residue (NVR) in mass per unit area for surfaces or mass per unit volume for liquids [14–18]. The cleanliness levels are based on contamination levels established in industry standard IEST-STD-CC1246D for particles from Level 1 to Level 1000 and for NVR from Level AA5 (10 ng/0.1 m2) to Level J (25 mg/0.1 m2) [17]. The cleanliness levels have been revised or redesignated in revision E of this standard [18]. The maximum allowable number of particles for each particle size range has been rounded in revision E, while the NVR designation levels have been replaced with a single letter R followed by the maximum allowable mass of NVR. For example, former NVR level J has the new designation R25; level A/2 is now R5E-1; and level AA5 is now R1E-5. These changes are discussed in greater detail in Volume 7 of this series [13]. Many of the products and manufacturing processes are also sensitive to, or they can even be destroyed by, airborne molecular contaminants (AMCs) that are present due to external, process or otherwise generated sources, making it essential to monitor and control AMCs. AMC is chemical contamination in the form of vapors or aerosols that can be organic or inorganic, and it includes everything from acids and bases to organometallic compounds and dopants [19,20]. A new standard ISO 14644–10, “Cleanrooms and associated controlled environments—Part 10: Classification of surface cleanliness by chemical concentration” [21] is now available as an international standard that defines the classification system for cleanliness of surfaces in cleanrooms with respect to the presence of chemical compounds or elements (including molecules, ions, atoms, and particles). In many commercial applications, the precision cleanliness level is defined as an organic contaminant level of less than 10 µg of contaminant per cm2, although for many applications the requirement is set at 1 µg/cm2 [17,18]. These cleanliness levels are either very desirable or are required by the function of parts such as medical devices, electronic assemblies, optical and laser components, precision mechanical parts, and computer parts. 3 Principles of UV-Ozone Cleaning
The basic principle of UV-O3 cleaning for removal of surface contaminants involves the reduction of organic contaminants into...