As device sizes in the semiconductor industries are shrinking, they become more vulnerable to smaller contaminant particles, and most conventional cleaning techniques employed in the industry are not as 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. The chapters in this Volume address the sources of surface contaminants and various methods for their collection and characterization, as well as methods for cleanliness validation. Regulatory aspects of cleaning are also covered. The collection of topics in this book is unique and complements other volumes in this series. 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.
This Volume complements other volumes in this series and:
- 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
- Includes new regulatory aspects
As device sizes in the semiconductor industries are shrinking, they become more vulnerable to smaller contaminant particles, and most conventional cleaning techniques employed in the industry are not as 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. The chapters in this Volume address the sources of surface contaminants and various methods for their collection and characterization, as well as methods for cleanliness validation. Regulatory aspects of cleaning are also covered. The collection of topics in this book is unique and complements other volumes in this series. 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 Includes new regulatory aspects
Front Cover 1
Developments in Surface Contamination and Cleaning: Cleanliness Validation and Verification 4
Copyright 5
Contents 6
Contributors 10
Preface 12
About the Editors 16
Chapter 1: Sources and Generation of Surface Contaminants and Their Impact 18
1. Introduction 18
2. Surface Cleanliness Levels 19
3. Sources and Generation of Contaminants 28
3.1. Particles 32
3.2. Thin Film or Molecular Contamination 37
3.3. Ionic Contamination 39
3.4. Microbial Contamination 41
4. Impact of Contaminants 44
4.1. Particle Contamination 44
4.1.1. Health Effects 48
4.2. Molecular Contamination 50
4.3. Ionic Contamination 51
4.4. Microbial Contamination 53
5. Summary and Conclusions 55
Acknowledgments 55
Disclaimer 55
References 55
Chapter 2: Mid-IR Spectroscopy as a Tool for Cleanliness Validation 68
1. Background 68
2. Principles of Grazing-Angle FTIR 70
3. Description of the Method 71
4. Advantages and Disadvantages 74
4.1. Direct, Real-Time Method 74
4.2. Detect Anything With An IR Spectrum 75
4.3. Automation 75
4.4. Access to Small Spaces/Flat Surfaces 75
5. Results and Applications 75
5.1. Aerospace 75
5.2. Manufacturing 76
5.3. Pharmaceutical Applications 77
5.4. Explosives and Chemical Warfare Agents 78
5.5. Tank Trials 79
5.6. IRRAS by Direct Reflectance 80
6. Future Developments 81
7. Summary 82
References 82
Chapter 3: Optically Stimulated Electron Emission: A Powerful Tool for Surface Cleanliness Monitoring 86
1. Introduction 86
2. OSEE Principle 88
2.1. Resolution 91
2.2. Repeatability and Reproducibility 91
2.3. Calibration 92
2.4. Factors Affecting OSEE 93
2.4.1. Short-Term Factors 93
2.4.1.1. Length of Time the Sample Surface is Exposed to UV Light 93
2.4.1.2. Distance of the OSEE Sensor from the Surface 95
2.4.1.3. Line Voltage 95
2.4.1.4. Ambient Temperature 96
2.4.1.5. Atmospheric Pressure 96
2.4.1.6. Sample Not Properly Grounded 97
2.4.1.7. Surface Finish 97
2.4.1.8. Air Flow/Turbulence Past the OSEE Sensor 97
2.4.1.9. Humidity 97
2.4.1.10. Static Charge 98
2.4.2. Long-Term Factors 99
2.4.2.1. UV Light Intensity 99
2.4.2.2. Collector Bias Voltage 99
3. Photoemitting Materials 99
3.1. Substrate Emitting and Contaminant Nonemitting 99
3.2. Substrate Nonemitting and Contaminant Emitting 102
3.3. Both Substrate and Contaminant Emitting 102
3.4. Both Substrate and Contaminant Nonemitting 104
4. Applications of OSEE 104
4.1. Surface Cleanliness Monitoring 104
4.1.1. Establishing Surface Cleanliness Level 105
4.1.1.1. Selecting an Appropriate Cleanliness Monitoring Technique 105
4.1.1.2. Establishing Acceptable Level of Cleanliness 106
4.1.1.2.1. Empirical Approach 106
4.1.1.2.2. Quantitative Approach 106
4.1.2. Example Applications of Surface Cleanliness Monitoring 107
4.1.2.1. Prebond Surface Quality 107
4.1.2.1.1. Application 1 107
4.1.2.1.2. Application 2 108
4.1.2.1.3. Application 3 108
4.1.2.2. Surface Finish 109
4.1.2.3. Selecting the "Right" Cleaning Process 110
4.1.2.4. Optimizing a Cleaning Process 110
4.1.2.5. Contamination Detection on Weld Surfaces 111
4.1.2.6. Copper Foil Characterization and Cleanliness Testing 111
4.1.2.7. Inspection for Flux Residue on Electronics Assemblies 112
4.1.2.8. Detecting of Fingerprints on Beryllium Mirrors 112
4.1.2.9. Graphite/Epoxy, Composite Skins on Honeycomb Panels 113
4.1.2.10. Battery Vent Discs 113
4.1.2.11. Solvent Rinse Cleanliness Verification 113
4.1.2.12. Steel Surface Oxidation After Pickling 115
4.1.2.13. Performance Monitoring of an Aqueous Cleaner for Metal Surface Finishing Processes 115
4.1.2.14. Other Applications 116
4.2. Detecting Absence/Presence of Films/Coatings 117
4.2.1. Establishing Acceptance Criteria 117
4.2.2. Example Applications 118
4.2.2.1. Computer Hard Disk Manufacturing 118
4.2.2.2. Aircraft Industry 118
4.2.2.3. Automotive Industry 119
4.3. Measuring Thickness of Thin Films/Coatings 119
4.3.1. Establishing OSEE versus Thickness Relationship 120
4.3.2. Example Applications 121
4.3.2.1. Computer Hard Disk 121
4.3.2.2. Welding Wire 122
5. Summary 122
References 123
Chapter 4: Methods for Verifying Medical Device Cleanliness 126
1. Background 126
2. Cleaning Issues and Concerns with Medical Devices 128
3. Extraction Techniques 130
4. Cleaning of Metal and Ceramic Components 132
5. Device Compatibility-Types of Tests and Description 134
6. Test Methods to Identify Contaminants in Extracts 136
6.1. Chromatographic Analysis 136
6.2. Spectrophotometric Analysis 136
6.2.1. Infrared 136
6.2.2. Ultraviolet/Visible Spectroscopy 137
6.3. Total Organic Carbon 137
6.4. Gravimetric Analysis 137
7. Setting Limits and Biological Safety Assessment 137
8. Validation 139
9. Sources of Contamination 140
10. Cleanliness Standards, Nonviable Contamination 141
10.1. Setting Allowable Limits 141
10.2. Extraction and Gravimetric Analysis 142
10.3. Quality Management Systems 142
11. Future Developments 142
12. Conclusion 143
References 144
Chapter 5: Cleaning Validation and Its Regulatory Aspects in the Pharmaceutical Industry 146
1. Introduction 148
1.1. Purpose 149
1.2. Reasons 149
1.3. Contaminant 150
1.3.1. Types of Contamination 151
2. Good Manufacturing Practice in API Manufacturing 151
2.1. Designing the Cleaning Process in Manufacturing Plants 151
2.2. Equipment in the Manufacturing Plant 151
2.2.1. Equipment Design Considerations 151
2.2.2. Equipment Characteristics 152
2.2.3. Construction Materials 152
2.2.4. Dedicated and Nondedicated Manufacturing Equipment 152
2.3. Personnel 153
2.4. Heating, Ventilation, and Air Conditioning System 153
2.5. Clothing and Footwear 153
3. Establishing the Acceptance Limits 153
3.1. Doses 154
3.2. Approaches in Establishing the Acceptable Carryover Quantity 154
3.2.1. Approach 1 (Dose Criterion) 154
3.2.2. Approach 2 (10ppm Criterion) 155
3.2.3. Approach 3 (Visually Clean Criterion) 155
3.3. Limits Based on Medical or Pharmacological Potency of the Product 155
3.3.1. The Basis for Quantitative Limits 155
3.4. Limits Based on Toxicity of the Residue 156
3.5. Risk Levels in Cleaning Validation 157
3.6. Use of ACQ for a Level 0 or Level 1 Changeover 158
4. Cleaning of Equipment 158
4.1. Cleaning Methods 158
4.1.1. Types of Residue 158
4.2. Cleaning Mechanisms 158
4.2.1. Types of Cleaning Mechanisms 160
4.2.1.1. Mechanical Action 160
4.2.1.2. Dissolution 160
4.2.1.3. Saponification 160
4.2.1.4. Detergency 161
4.2.1.4.1. Wetting 161
4.2.1.4.2. Emulsification 161
4.2.1.5. Chemical Reaction 161
4.3. Grouping of Products 162
4.4. Cleaning Process 162
4.4.1. Types of Cleaning Processes 162
4.5. Cleaning Porous Equipment 163
4.6. Cleaning Frequency 163
4.7. Product Attributes 164
4.7.1. Between Batches of Different Products 164
4.7.2. Between Batches of the Same Product 164
4.8. Postcleaning Equipment Storage 164
4.9. Microbiological Considerations 164
4.10. Documentation 165
4.11. Inspection and Sampling Plan 165
5. Sampling Methods for Cleaning Validation 165
5.1. Swabbing Technique 165
5.2. Rinse Sampling 166
5.3. Placebo Sampling 168
5.4. Microbiological Sampling 168
6. Cleaning Method Specificity 168
6.1. Recovery in Swab Sampling 168
6.1.1. Chemical Recovery from Spiked Swabs 169
6.1.2. Recovery from Spiked Plates/Coupons 169
6.1.3. Microbial Recovery from Spiked Swabs and Plates/Coupons 169
6.2. Stability Issues in Cleaning Method 169
6.2.1. Surface Aging 170
6.2.2. Swab Aging 170
6.2.3. Timing of Sampling 170
6.2.4. Time Between End of Manufacturing to Beginning of Cleaning 170
6.2.5. Number of Sample Sites 170
6.2.6. Diagram of Sampling Sites 170
6.2.7. Microbiological Sampling Sites 170
6.2.8. Sample Storage and Identification 171
6.2.9. Sampling Documentation: Data Sheet 171
7. Solvents Used for Cleaning 171
7.1. Builders 172
7.2. Cleaning Cycle 172
7.2.1. Prewash 172
7.2.2. Alkali Wash 173
7.2.3. Postalkali Wash 173
7.2.4. Acid Wash 173
7.2.5. Final Rinse 173
7.2.6. Air Flushing for Storage 173
8. Cleaning Agents 174
8.1. Grouping of Cleaning Agents 174
8.2. Selection of a Cleaning Agent 175
8.3. Water 175
8.4. Alkaline Agents 175
8.4.1. Sodium Hydroxide 176
8.4.2. Sodium Hydroxide/Hypochlorite Solutions 176
8.5. Acidic Agents 176
8.5.1. Phosphoric Acid 176
9. Analytical Methods 176
9.1. Specific Methods 178
9.2. Nonspecific Methods 178
9.3. Various Analytical Techniques in Cleaning Validation 179
9.3.1. pH 179
9.3.2. Conductivity 179
9.3.3. Total Organic Carbon 179
9.3.4. Enzymatic (Bioluminescence) 180
9.3.5. Light Microscopy 180
9.3.6. Gravimetric Method 180
9.3.7. Thin-Layer Chromatography 181
9.3.8. Capillary Zone Electrophoresis 181
9.3.9. Fourier Transform Infrared Spectroscopy 181
9.3.10. Enzyme-Linked Immunosorbent Assay 182
9.3.11. Atomic Absorption Spectroscopy 182
9.3.12. Ultraviolet Spectrophotometry 183
9.3.13. Microbial and Endotoxin Detection and Testing 183
10. Cleaning Development Phase 183
10.1. Standard Operating Procedures 183
10.2. Operator 184
10.3. Operator Training 184
11. Cleaning Validation Protocol 185
11.1. A Model Cleaning Validation Protocol 185
12. Validation Report 194
13. The FDA Cleaning Validation Guideline 194
13.1. FDA Requirements 195
13.2. Acceptance Criteria 195
14. Effective Cleaning Validation Maintenance Program 196
14.1. Equipment Cleaning Validation and Maintenance 196
14.2. Overview of Cleaning Validation Program 197
14.3. Cleaning Validation Lifecycle Management 197
14.4. Cleaning Validation Chart 198
15. Summary 198
References 199
Index 204
Sources and Generation of Surface Contaminants and Their Impact
Rajiv Kohli The Aerospace Corporation, NASA Johnson Space Center, Houston, Texas, USA
Abstract
Surface contaminants are ubiquitous. The most common types of contamination are particles, molecular contamination, ionic contamination, and microbial contamination. This chapter provides an overview of the sources and generation of these contaminants and discusses some of the impacts of the contaminants.
Keywords
Contaminants
Sources
Generation
Impact
Particles
Molecular contamination
Microbial contamination
Ionic contamination
Chapter Outline
1 Introduction 1
2 Surface Cleanliness Levels 2
3 Sources and Generation of Contaminants 11
3.1 Particles 15
3.2 Thin Film or Molecular Contamination 20
3.3 Ionic Contamination 22
3.4 Microbial Contamination 24
4.1 Particle Contamination 27
4.1.1 Health Effects 31
4.2 Molecular Contamination 33
4.3 Ionic Contamination 34
4.4 Microbial Contamination 36
Disclaimer 38
References 38
Acknowledgments
The author would like to thank the staff of the STI Library at the Johnson Space Center for help with locating obscure reference articles.
1 Introduction
Contaminants are ubiquitous in nature as by-products of natural processes as well as by-products of human and industrial activities. A contaminant is any material, substance, or energy that is unwanted or adversely affects the product [1]. Surface contamination, the subject of this chapter, can be in many forms and may be present in a variety of states on the surface. For example, typical surface defects on hard disk drive (HDD) components include roughness and wear, flaking, porosity, loose debris, nonvolatile residue (NVR), flash, bloom and inclusions on plastics, burrs and rust on metals, lubricant leakage in ball bearings, packaging debris, and uncured adhesives [2,3]. A particle with dimensions similar to the flying height between the recording head and the disk that is trapped between the head and the disk in a disk drive can cause catastrophic failure of the drive [3–6]. Ionic contaminants also can lead to corrosion of the recording head and failure of the drive [7]. In semiconductor wafer processing, airborne molecular contaminants (AMCs) can cause various defects, such as haze on the wafer surface or introduction of foreign dopants, which can lead to loss of the entire product yield [8–10]. The most common categories of surface contaminants are given below.
• Particles such as dust, metals, ceramics, glass, and plastics in the submicrometer to macro size range
• Thin film or molecular contamination that can be organic (hydrocarbons) or inorganic (acids gases, bases)
• Cationic (such as Na+ and K+) and anionic (such as Cl−, F−, Br−, 3−, 33−, and 43−) contamination
• Microbial contamination (bacteria, fungi, and algae).
Other contaminant categories include toxic and hazardous chemicals, radioactive materials, and by-products of manufacturing processes, which are identified on surfaces employed in specific industries, such as metals processing, chemical production, nuclear industry, pharmaceutical manufacture, and food processing, handling, and delivery. Energy sources or changes of state, such as light, electric and magnetic fields, heat, and radiation, can also be contaminating. For example, light is usually desirable, but in the photographic film development process, it becomes a contaminant. Magnetic fields can contaminate iron and nickel magnets. Many plastics, when exposed to ultraviolet light, slowly release inert particles due to their degradation. Common contamination sources 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 also soil a surface. The emphasis in this chapter will be on particles as contaminants deposited on the surface of products manufactured in controlled environments such as clean rooms. Aerosol particles and their behavior will not be considered here. There are numerous references, including books and journals, which address all aspects of aerosols, including single aerosol particles [11–24]. The discussion in this chapter is necessarily an overview of the subject matter and no attempt is made at comprehensiveness. Each of the thousands of references to contamination, cleanliness, and cleaning published each year mentions some aspect of the sources and generation of contaminants, making it nearly impossible to comprehensively treat the subject matter in this chapter. The references cited do provide sources of additional information.
2 Surface Cleanliness Levels
Surface cleaning specifications are typically based on the amount of specific or characteristic contaminant remaining on the surface after it has been cleaned. Space agencies worldwide specify surface precision cleanliness levels for space hardware by particle size (in the micrometer (μm) size range) and number of particles, as well by film contamination represented by NVR [25,26]. The cleanliness levels are based on contamination levels established in industry standard IEST-STD-CC1246D (which replaced the original cleanliness standard MIL-STD-1246 [27]) 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) as shown in Table 1.1 [28]. The cleanliness levels have been revised or redesignated in revision E of this standard [29]. 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. However, this revision has not yet been officially adopted by the space agencies. Table 1.2 lists the surface cleanliness levels for particle contamination in revision E of IEST-STD-CC1246. Table 1.3 compares NVR contamination designation levels between revisions D and E of the standard.
Table 1.1
Product Surface Cleanliness Levels for Commercial and Noncommercial Applications Defined in IEST-STD-CC1246 Revision D...
| Erscheint lt. Verlag | 24.11.2014 |
|---|---|
| Sprache | englisch |
| Themenwelt | Technik ► Bauwesen |
| Technik ► Elektrotechnik / Energietechnik | |
| Wirtschaft ► Betriebswirtschaft / Management ► Unternehmensführung / Management | |
| ISBN-10 | 0-323-31145-8 / 0323311458 |
| ISBN-13 | 978-0-323-31145-8 / 9780323311458 |
| Haben Sie eine Frage zum Produkt? |
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