SEMICONDUCTOR SAFETY HANDBOOK pptx

1 Injury and Illness of Semiconductor Workers: Experience and “High Tech” industry, the semiconductor industry is characterized by rapidchanges, based on intense competition to place inc

HANDBOOKSafety and Health in the

mechanical, including photocopying, recording or

by any information storage and retrieval system,

without permission in writing from the Publisher.

Library of Congress Catalog Card Number: 97-24032

ISBN: 0-8155-1418-2

Printed in the United States

Published in the United States of America by

Noyes Publications

369 Fairview Avenue, Westwood, New Jersey 07675

10 9 8 7 6 5 4 3 2 1

Library of Congress Cataloging-in-Publication Data

Semiconductor safety handbook : safety and health in the semiconductor industry / edited by Richard A Bolmen, Jr.

p cm.

Includes bibliographical references and index.

ISBN 0-8155-1418-2

1 Semiconductor industry United States Safety measures.

2 Integrated circuits Design and construction Safety measures.

I Bolmen, Richard A.

TK7836.S463 1997

636.11' 96213815 dc21 97-24032

CIP

NOYES PUBLICATIONS

Westwood, New Jersey

Richard A Bolmen, Jr is presently

with Aon Risk Services Prior to that, hewas Senior Vice President of Minet RiskServices, Palo Alto, California, responsiblefor the development and delivery of Minet’sWorkers' Compensation, Disability Man-agement and Hazards Management con-sulting services nationwide He was alsowith American Risk Consultants and Marsh

& McLennan Protection Consultants Hehas over a decade of experience develop-ing and managing safety, environmentalworkers' compensation and risk manage-ment programs for semiconductor manu-facturing companies

Mr Bolmen has served as the NorthernCalifornia Regional Director and was on theBoard of Directors for the SemiconductorSafety Association He also served as theDivision Safety Director for SemiconductorEquipment and Materials International from

1986 to 1989

Series Editor: Richard A Bolmen, Jr.

CODE COMPLIANCE FOR ADVANCED TECHNOLOGY FACILITIES: by William R Acorn SEMICONDUCTOR INDUSTRIAL HYGIENE HANDBOOK: by Michael E Williams and David G Baldwin, and Paul C Manz

SEMICONDUCTOR SAFETY HANDBOOK: edited by Richard A Bolmen, Jr.

Paul C Manz

ConsultantMatawan, NJ

To the best of our knowledge the information in this publication is accurate; however the Publisher does not assume any responsibil- ity or liability for the accuracy or completeness of, or consequences arising from, such information This book is intended for informational purposes only Mention of trade names or commercial products does not constitute endorsement or recommendation for use by the Publish-

er Final determination of the suitability of any information or product for use contemplated by any user, and the manner of that use, is the sole responsibility of the user We recommend that anyone intending to rely on any recommendation of materials or procedures mentioned in this publication should satisfy himself as

to such suitability, and that he can meet all applicable safety and health standards.

It is hard to imagine that less than fifteen years ago building and firecodes specific to the construction of a wafer fabrication facility were just inthe process of being developed Detection and evaluation of leaking under-ground storage tanks and epidemiological health studies aimed at qualifyingand quantifying our “cleanroom” image were in their infancy stages and Cal-OSHA had just completed the first in-depth study of the industry’s chemicalprocesses and associated industrial hygiene exposures From a technologyperspective, 64 k RAM chips were the hot item for a newly developingcomputer game market and the 8088 microprocessor provided previouslyunavailable information processing and storage capabilities at an affordableprice “Silicon Valley,” stretching from Palo Alto to South San Jose, stillretained much of its agricultural base and we were always amazed at thebeauty and contrast of blooming mustard fields and plum orchards adjacent

to wafer fabs, deionized water plants, and chemical storage areas SEMI wasdeveloping a Safety Division, and the Semiconductor Safety Association’s(SSA) annual conference was in its third year attended by a handful of healthand safety professionals

Fifteen years later, “Silicon Valley,” as we have known it, now exists

in cities like Austin, Phoenix and Boston Megafabs with property valuesexceeding $1 billion have become commonplace We think in terms ofgigabytes of hard disk storage for our home computers and the Internet hasbecome a way of life The Pentium is becoming passé as the next generation

of microprocessor looms on the horizon and submicron technology continues

to push the envelop of our processing capabilities

However great our technological advances have been over this period

of time, they have not been exclusive to semiconductors and related hightechnology products Interwoven within our semiconductor technologydevelopment has been the development of technologies aimed at identifying,evaluating and mitigating the environmental, health and safety (EH&S) risksand exposures associated with the manufacturing and packaging of inte-grated circuits Driving and advancing these technologies have been interna-tional efforts by SEMI’s Safety Division, the Semiconductor Safety Associa-tion (SSA), and the Semiconductor Industry Association (SIA)

The purpose of the Semiconductor Safety Handbook is to provide a

current, single source reference for many of the primary semiconductorEH&S technologies and disciplines To this end, we have assembled acomprehensive text written by some of the leading experts in EH&S in thesemiconductor industry This text has taken three years to complete and hasinvolved tremendous effort and commitment by the text’s authors

We have attempted to construct a reference manual that is hensive in its coverage of the technical aspects of each individual subject,while at the same time addressing practical applications of each topic Thescope of this text, from its inception, was intended to address significantlymore than what would typically be classified under the definition of “safety.”However, we felt that all of the chapters have a direct application to theprotection and preservation of semiconductor employees, the surroundingcommunities and the environment As such, “The Semiconductor SafetyHandbook - Safety and Health in the Semiconductor Industry” seemed anappropriate title

compre-The Semiconductor Safety Handbook opens with Chapter 1, “Injury

and Illness of Semiconductor Workers: Experience and EpidemiologicalStudies,” by Donald Lassiter and James Stewart Donald Lassiter has been

a key figure in the development and maintenance of the semiconductorindustry’s Occupational Health System (OHS) injury and illness data base.Development of the OHS system was sponsored by SIA in the early 1980’sand OHS has become the leading occupational illness and injury trackingdatabase for the industry The OHS system has been in place since 1983 andhas participation from approximately one-quarter to one-third of the USsemiconductor industry Data from the OHS system as well as annualincidence rates for OSHA-recordable work injuries and illnesses are pre-sented and compared for the time period 1983–1995 The co-author of thischapter, James Stewart, provides a comprehensive review of epidemiologi-cal health studies that have been conducted for the semiconductor industry

This overview chronicles initial health studies, beginning with the University

of Massachusetts reproductive study for Digital Equipment Corporation in

1984, through the recently published University of California, Davis, conductor Health Study, a multi-disciplinary investigation which targetedreproductive and other health outcomes in the semiconductor industry

Semi-In Chapter 2, “Environmental Compliance in the SemiconductorIndustry: Detection, Correction and Prevention,” we change gears fromprotection of employees to protection of the environment Local, state andfederal environmental regulations have increased exponentially over the pastdecade in response to the plethora of hazardous chemicals used, stored,treated and disposed of (as hazardous waste) in US manufacturing Few USindustries have experienced the impact of the combined environmentalregulatory and control technology requirements as the semiconductor indus-try Our authors, Robert Kuykendall and Rollin Chew collectively have overfifty years experience in environmental technology and compliance andpresent one of the most comprehensive reviews of environmental regulation,control and mitigation technologies written on the semiconductor industry

Key to the understanding of environmental, health and safety issues

in the semiconductor industry is an understanding of the chemicals used in themanufacture and packaging of semiconductors and semiconductor relatedtechnologies Chapter 3, “Chemical Hazards in Semiconductor Operations,”co-authored by Tom Hawkinson and Daryl Korpela offers an overview of thetypes of chemicals used in the semiconductor industry as well as the relatedprocesses

The chemical hazards of semiconductor manufacturing processes aswell as the assessment, monitoring and control of these hazards are given anin-depth treatment by two of the most senior members of the industry’s EH&Scommunity: Michael Williams and David Baldwin Involved with semicon-ductor safety and industrial hygiene from the time these issues were firstrecognized within the industry, they provide invaluable insight to both thescience and practical application of industrial hygiene principles and prac-tices in Chapter 4, “Industrial Hygiene.”

While the majority of our efforts, as a health and safety communitywithin the semiconductor industry, have been aimed at the control ofhazardous materials, some of our most significant safety exposures continue

to be those associated with electrical hazards Historically, electricalaccidents have been the leading cause of serious injuries and fatalities in thesemiconductor industry Ironically, electrical safety is an area where we havethe least amount of technical and practical expertise available to us as an

industry This is what makes Clifford Oliver’s Chapter 5, “ElectricalHazards,” a key reference Clifford’s two decades of experience in electricalsafety combined with his extensive knowledge of semiconductor processingand equipment, offer a unique perspective and valuable insight into thispervasive hazard.

Chapter 6, “Radiation Safety,” again teams up co-authors DavidBaldwin and Michael Williams In this chapter, we are offered a comprehen-sive review of the various classifications and associated hazards of radiation

as well as potential sources and specific radiation exposures in a cleanroomenvironment Included in this chapter are industrial hygiene identification,monitoring and control practices specific to semiconductor processes andequipment

David Rainer and Lisa Brooks, co-authors of Chapter 7, tion, Evaluation and Control of Some Plasma Processing Hazards,” provide

“Recogni-an overview of the plasma process as well as the various physical “Recogni-andchemical hazards associated with plasma processing

As megafabs with building values exceeding $1 billion have becomecommonplace, so has the emphasis on protecting those facilities and theirbusiness viability from damage and business interruption as a result of a fire

or smoke contamination of a Class I wafer fab Integral to these efforts hasbeen fire and property protection standards and compliance efforts of themajor property insurers To address these exposures, Robert Pearce has

authored Chapter 8, “Fire Protection Technology for Semiconductor

Opera-tions.” This chapter begins with the history of fire protection in thesemiconductor industry The chronology discusses the time period whenthere were no specific building and fire codes for semiconductor fabs otherthan those written by major property insurers The evolution and develop-ment of Highly Protective Risk (HPR) standards, specific to semiconductoroperations, are also discussed in addition to present day property and fireprotection issues for large Class I wafer fabrication facilities This chapter

is unique in its breadth and scope and offers fire and property protectionmethodologies and scenarios from the micro to the macro Issues from siteselection for a wafer fab to protection of individual pieces of processingequipment are addressed by one of the industry’s most experienced propertyprotection practitioners

The construction of a wafer fabrication facility involves numerouscomplex building and fire codes The application and enforcement of thesecodes, by multiple building and fire code officials, with varying levels ofunderstanding and expertise, add an additional level of complexity in the

construction process The primary objective of the various codes are toensure the safety of building occupants as well as provide for a high level ofprotection of the building, its contents and processes Experience hasdemonstrated that an in-depth understanding of both the “letter” and “intent”

of the codes is essential by those responsible for the building and operation

of a semiconductor processing facility To this end, William Acorn hasauthored Chapter 9, “Building and Fire Codes Impacting the SemiconductorIndustry.” In addition to providing a critical review of the fire and buildingcodes specific to the construction, operation and occupancy of semiconductorand related occupancies, we are also provided a key reference guide tounderstanding the intent and practical application of these codes by one of theindustry’s leaders in this arena

Of all the chemicals utilized by the semiconductor industry, no onegroup is as varied in its chemical properties, storage and delivery, monitoringand criticality to the semiconductor manufacturing process as process gases.With a wide range of toxicity, corrosivity, flammability and health hazards,compressed gases represent perhaps the most challenging and enigmaticelements of chemical hazards and control technologies to the industry Assuch, process gas handling and the systems designed to control the hazardsand at the same time facilitate production, are essential to our discussion.Richard Brookman and Bruce Tibbott have co-authored Chapter 10, “Gasesand Gas Equipment,” which provides one of the most extensive treatises todate on this subject Additionally, the gas data sheet references provided onthe various chemical classifications, chemical and physical characteristics,and hazard information for the process gases utilized by the industry areinvaluable

A major control factor in the storage and dispensing of process gaseswithin semiconductor manufacturing is the requirement for monitoring ofspecific categories of hazardous production gases These monitoringrequirements are mandated by fire and building codes as well as local city andstate “model ordinances.” The monitoring systems must also integrate withprocess equipment, have alarm capabilities, detect gases at part per billionlevels and at the same time function twenty-four hours per day, seven daysper week These are just a few of the nuances and complexities involved

in hazardous gas monitoring Paul Manz’s Chapter 11, “Toxic GasMonitoring,” analyzes gas monitoring requirements and methodologies from

a technology, installation and utilization perspective This chapter provides

an overview of the origin of the requirements for monitoring process gasesthrough the present day “Toxic Gas Model Ordinance.” In addition to

monitoring requirements, types of detection methodologies, system tions, and selection of a gas monitoring systems are all discussed in greatdetail.

installa-The purpose of the Semiconductor Safety Handbook has been to

provide a comprehensive, hands-on reference to environmental, health andsafety issues critical to the semiconductor industry It was also our intent toproduce a text that provides a practical user’s guide for semiconductorenvironmental, health and safety practitioners as well as those individualsresponsible for operation, maintenance and production in wafer fabricationfacilities It is our belief that the contributions of these authors have achieved

that goal and we hope that you find the Semiconductor Safety Handbook a

useful addition to your library

San Francisco, California Richard A Bolmen, Jr.September, 1997

x v

Contents

1 Injury and Illness of Semiconductor Workers: Experience

and Epidemiologic Studies 25

Donald V Lassiter and James H Stewart 1.0 INTRODUCTION 25

2.0 REVIEW AND DISCUSSION OF SEMICONDUCTOR INDUSTRY WORK INJURIES AND ILLNESSES 28

2.1 Work Injury and Illness Statistical Program of U.S BLS 29

2.2 OSHA Recordkeeping System 29

2.3 Usefulness of BLS Survey to U.S Semiconductor Industry 31

2.4 Occupational Health System (OHS) 32

2.5 Work Injury and Illness Experience of Semiconductor Workers 34

3.0 REVIEW AND DISCUSSION OF EPIDEMIOLOGIC INVESTIGATIONS 44 3.1 UMASS—Digital Equipment Corporation (DEC) Historical Cohort Study 44

3.2 UC Davis-Semiconductor Industry Association Study 46

3.3 Johns Hopkins University-IBM Study (JHU) 53

3.4 Discussion of Reproductive Epidemiology in the Semiconductor Industry 56

4.0 CONCLUSION 56

REFERENCES 57

2 Environmental Compliance in the Semiconductor Industry:

Detection, Correction and Prevention 59

Robert G Kuykendall and Rollin C Chew 1.0 INTRODUCTION 59

2.0 EXTERNAL AND INTERNAL SOURCES AFFECTING COMPLIANCE 61

2.1 External Factors Affecting Compliance 63

2.2 Internal Factors Affecting Compliance 64

3.0 DETECTION OF ENVIRONMENTAL COMPLIANCE AND MANAGEMENT ISSUES 68

3.1 Development of Environmental Audit Programs 69

4.0 CORRECTIVE ACTION FOR ENVIRONMENTAL COMPLIANCE AND MANAGEMENT ISSUES 79

4.1 Use of Audit Program Results 82

5.0 MITIGATION AND PREVENTION OF ENVIRONMENTAL COMPLIANCE AND MANAGEMENT ISSUES 84

6.0 ADOPTING PROACTIVE ENVIRONMENTAL STRATEGIES 85

7.0 GOING BEYOND COMPLIANCE—HOLISTIC CONSIDERATIONS 86

7.1 The Green Advantage 87

7.2 Corporate Environmentalists 89

REFERENCES AND SOURCE MATERIALS 92

APPENDIX A: EPA POLICY ON ENVIRONMENTAL AUDITING 94

APPENDIX B: ENVIRONMENTAL COMPLIANCE AUDIT CHECKLIST 102

I GENERAL 102

II COMPLIANCE AUDIT 103

A.Air 103

B Water 106

C TSCA (Toxic Substance Control Act) 111

D Asbestos 114

E Proposition 65 115

F Solid Waste 116

G Hazardous Waste 118

H Hazardous Materials Management 124

I Underground Storage Tanks 129

J Aboveground Storage Tanks 131

K CERCLA Notification 134

L Pesticides 135

III ENVIRONMENTAL MANAGEMENT AUDIT 138

A Environmental Policy and Procedures 138

B Management Support and Attention 140

C Capital Project Coordination 142

D Chemical Purchasing, Receiving & Inventory Control 142

E Emergency Procedures & Spill History 145

F Housekeeping 147

G Property Transfer 148

H Communications 148

I Monitoring Regulatory Activity 151

J Recordkeeping 152

STEP I: BASE FINE 154

STEP II: AGGRAVATING FACTORS IN SENTENCING 162

STEP III: FACTORS FOR ENVIRONMENTAL COMPLIANCE 172

STEP IV: GENERAL LIMITATIONS 177

STEP V: PROBATION — ORGANIZATIONS 179

3 Chemical Hazards in Semiconductor Operations 187

Thomas E Hawkinson and Daryl B Korpela OVERVIEW 187

1.0 PHOTOLITHOGRAPHY 189

2.0 WET ETCH 192

3.0 DRY ETCH 193

4.0 IMPLANT/DIFFUSION 195

5.0 CLEANING 197

6.0 METALLIZATION 197

7.0 MAINTENANCE ISSUES 198

8.0 USE OF GASES 199

4 Industrial Hygiene 204

David G Baldwin and Michael E Williams 1.0 INTRODUCTION 204

2.0 INDUSTRIAL HYGIENE MONITORING 204

2.1 Overview of IH Monitoring 204

2.2 Assessment Tools 209

2.3 Biological Monitoring 218

2.4 Airborne Contamination by Process 219

2.5 Continuous Gas Monitoring 238

2.6 Surface Contamination 240

2.7 Noise 241

3.0 Personal Protective Equipment 242

3.1 Background 242

3.2 Chemical Protective Gloves 243

3.3 Respiratory Protection 251

4.0 ODOR IDENTIFICATION 256

5.0 RECORDKEEPING 259

5.1 General 259

5.2 Continuous Monitor Records 261

5.3 Ventilation Records 261

5.4 Employee Communication 261

5.5 Personnel Records 262

ACKNOWLEDGMENTS 262

REFERENCES 262

5 Electrical Hazards 269

Clifford E Oliver 1.0 INTRODUCTION 269

2.0 WHERE DO WE START? 270

2.1 How Do You Identify an Electrical Hazard Before Someone Gets Hurt? 270

3.0 TERMINOLOGY 272

4.0 HUMAN EFFECTS 274

5.0 SCENARIO OF AN ELECTRICAL SHOCK 278

6.0 WHAT REALLY HAPPENS? 279

7.0 REPORTING 280

8.0 COMMON ELEMENTS OF ELECTRICAL ACCIDENTS/ACCIDENT INVESTIGATION 282

9.0 ELECTRICAL HAZARD MANAGEMENT 288

10.0 TYPICAL ELECTRICAL HAZARDS 289

10.1 Housekeeping Considerations 290

10.2 General 290

10.3 Installation 290

10.4 Guarding 291

10.5 Safety Signs 291

10.6 Labeling 291

10.7 Clearance 292

10.8 Switches 292

10.9 Manuals 292

10.10 Water, Electricity, and Ground 293

10.11 Extension Cords and Power Strips 293

10.12 Electrical Plugs: 2- vs 3-Prong 120-Volt 294

10.13 Circuit Breakers and Breaker Panel Boxes 294

10.14 Interlocks 295

10.15 Hazardous Locations 295

10.16 Fire Extinguishers 296

11.0 HAZARD-BASED, SAFETY PLANNING 297

12.0 LOCKOUT/TAGOUT 298

12.1 OSHA 298

12.2 Procedures 298

12.3 Basics 298

13.0 ELECTRICAL SAFETY COOKBOOK–What can be done? What can I do? 299

13.1 Understand 299

13.2 Communicate 300

13.3 Never Work Alone 300

13.4 Inspect 300

13.5 No Shortcuts 301

13.6 Safety Design Reviews 301

13.7 Caution 301

13.8 Final Thoughts 301

REFERENCES 302

6 Radiation Safety 304

David G Baldwin and Michael E Williams 1.0 INTRODUCTION 304

2.0 EXTREMELY LOW FREQUENCY ELECTROMAGNETIC FIELDS (ELF/EMF) 305

3.0 RADIOFREQUENCY/MICROWAVE RADIATION 313

4.0 LASERS 315

5.0 ULTRAVIOLET RADIATION 317

6.0 IONIZING RADIATION 318

6.1 X-Ray Generating Machines 319

6.2 Radioactive Material 321

ACKNOWLEDGMENTS 324

REFERENCES 324

7 Recognition, Evaluation and Control of Some Plasma Processing Hazards 327

David Rainer and Lisa Brooks CHEMICAL SAFETY MANAGEMENT IN A NUTSHELL 327

1.0 INTRODUCTION 328

2.0 HAZARD EVALUATION 330

3.0 PROCESS HAZARD REVIEW 332

4.0 OTHER MECHANISMS TO ADDRESS EQUIPMENT SAFETY CONCERNS 338

5.0 GAS CHEMICAL SAFETY 339

5.1 Compressed Gas Cylinder Safety 346

5.2 Flow Restrictors 348

5.3 Gas Flow through Limiting Orifices 350

5.4 Sizing the Orifice 352

5.5 Orifice Purging 353

5.6 Gas Storage Locations and Gas Cabinets 353

5.7 A System Approach to Gas Safety 356

5.8 917 Alarm Response Processor 358

5.9 PFD 959 Gas Panel Controllers 358

5.10 904A Wall Valves 358

5.11 Loss of Essential House Services 359

5.12 Action-Reaction 359

6.0 TOXICOLOGY 360

6.1 History and Development 360

6.2 Occupational Toxicology 361

6.3 Basic Concepts of Toxicology 361

6.4 Classification of Toxic Effects 368

6.5 Toxicology of Halogen-Containing Plasma Etching Gases 371

6.6 Fluorine and Fluorine-Containing Gases 371

6.7 Chlorine and Chlorine-Containing Gases 372

6.8 Bromine and Bromine-Containing Gases 373

7.0 SOURCES OF INFORMATION 374

REFERENCES 375

ADDITIONAL REFERENCES 377

8 Fire Protection Technology for Semiconductor Operations 378

Robert J Pearce 1.0 INTRODUCTION 378

1.1 History 378

1.2 Highly Protected Risk 379

1.3 Codes 380

2.0 SITE SELECTION 381

2.1 Introduction 381

2.2 Climate 382

2.3 Topography 382

2.4 Exposure 383

2.5 Utilities 384

3.0 CONSTRUCTION 387

3.1 Exterior Envelope 387

3.2 Cleanroom 387

4.0 AIR HANDLING SYSTEMS 389

4.1 Introduction 389

4.2 Construction Materials 390

4.3 High Efficiency Particulate Air Filters 390

4.4 System Design 391

4.5 Fume Exhaust System 393

5.0 SPRINKLER PROTECTION 396

5.1 Scope 396

5.2 NFPA Codes 396

5.3 Cleanroom Sprinkler Systems 396

5.4 Types of Sprinkler Systems 398

5.5 Room Protection 400

5.6 Service Aisles/Floors 400

5.7 Duct Sprinklers 401

5.8 Chemical Storage Areas 403

5.9 Added Reliability 404

6.0 WATER SUPPLIES 405

6.1 Scope 405

6.2 Primary Supply 406

6.3 Booster Pumps 406

6.4 Primary Fire Pumps 406

6.5 Drivers 407

7.0 SUPERVISION 409

7.1 Scope 409

7.2 Water Flow 409

7.3 Valve Tamper 410

7.4 Supervision of the Fire Pump 411

7.5 Other Alarms 411

7.6 Smoke Detection 411

7.7 Other Detectors 412

7.8 Signalling Systems 413

7.9 Proprietary Supervisory Service 414

7.10 Watchman Service 415

8.0 CHEMICAL HANDLING 416

8.1 Scope 416

8.2 Gases 416

8.3 Liquids and Solids 423

9.0 EQUIPMENT 425

9.1 Scope 425

9.2 Electrics 425

9.3 Materials of Construction 425

9.4 Heated Baths 426

10.0 HUMAN ENGINEERING 427

10.1 Scope 427

9 Building and Fire Codes Impacting the Semiconductor Industry 429

William R Acorn 1.0 UNDERSTANDING THE NEED FOR CODE COMPLIANCE 429

2.0 OVERVIEW OF APPLICABLE CODES 430

3.0 OVERVIEW OF UNIFORM BUILDING AND FIRE CODES 431

4.0 OCCUPANCY CLASSIFICATIONS 432

4.1 Control Area 432

5.0 CLASSIFICATION OF HAZARDOUS MATERIALS 439

5.1 Physical Hazards 439

5.2 Health Hazards 439

6.0 ALLOWABLE AREA AND SEPARATIONS 440

7.0 LOCATION 441

8.0 EXITING 442

9.0 EXIT CORRIDORS 444

10.0 SERVICE CORRIDORS 444

11.0 HAZARDOUS MATERIAL STORAGE AND DISPENSE ROOMS 445

11.1 Separation of HPMs 445

11.2 Flammable and Combustible Liquids 446

11.3 Toxic Gas Monitoring 446

11.4 Smoke Detection 446

11.5 Pyrophoric Materials 446

12.0 MECHANICAL HEATING, VENTILATING AND AIR CONDITIONING SYSTEMS 446

12.1 General 446

12.2 Recirculating Air Handling Systems 447

12.3 Exhaust Ventilation 447

12.4 HPM Storage Area Ventilation 448

12.5 Makeup Air 449

12.6 Emergency Ventilation and Operation 449

12.7 Air Handling System Isolation 449

13.0 FIRE SUPPRESSION 450

13.1 H-6 Occupancies 451

13.2 Cleanrooms 451

13.3 Storage Occupancies 452

13.4 Exhaust Ducts Containing Flammable Vapors 453

13.5 Exhaust Ducts Containing Corrosive Vapors 453

13.6 Gas Cabinets 453

13.7 Alternate Suppression Systems 454

14.0 ELECTRICAL POWER SYSTEMS 454

14.1 Transfer Switches 455

14.2 Emergency Shutoffs 455

14.3 Hazardous Area Electrical Requirements 457

15.0 LIFE SAFETY ALARM AND MONITORING SYSTEMS 458

15.1 Emergency Control Station (ECS) 458

15.2 Fire Alarm and Monitoring Systems 459

15.3 Continuous Toxic Gas Monitoring 460

15.4 Emergency Spill Alarm 463

15.5 Audible Alarm Evacuation 464

15.6 Visual Alarm Signaling 464

15.7 Fireman’s Command Station 464

16.0 RETROFIT AND RENOVATION OF HAZARDOUS FACILITIES TO COMPLY WITH “H” CODES 465

16.1 Renovation 465

16.2 Code Agency Liaison 466

17.0 PRIORITIZING CODE COMPLIANCE ISSUES 468

18.0 PHASING OF PROJECT CONSTRUCTION 469

18.1 Scheduling 470

18.2 Project Manager 470

18.3 Contractors 471

10 Gases and Gas Equipment 472

Richard P Brookman and Bruce Tibbott 1.0 INTRODUCTION 472

2.0 GAS DISTRIBUTION SYSTEMS IN PLANT PIPING 473

2.1 Materials of Construction 473

2.2 Compression Fittings 474

2.3 VCR Fittings 475

2.4 Orbitally Welded Fittings 475

2.5 Routing Considerations 476

2.6 Secondary Containment 476

2.7 Dedicated Versus Branched Lines 477

2.8 Pressure Testing 478

2.9 Leak Testing 4782.10 Particulate Testing 4793.0 GAS CYLINDERS—SAFE USE AND HANDLING 4793.1 Cylinder Types and Specifications 4793.2 Compressed Gas Cylinders 4803.3 Liquefied Gas Cylinders 4813.4 Cryogenic Cylinders 4823.5 Cylinder Valves and Safety Devices 4833.6 Cylinder Connections, Types and Uses 4843.7 Safety Devices (Reliefs, Fuse Plugs, RFO’s, Etc.) 4873.8 Receiving and Identification of Cylinders 4893.9 Leaking Cylinders 4903.10 Transportation and Storage 4913.11 Safe Use of the Cylinder 4934.0 GENERAL GAS HANDLING EQUIPMENT 4944.1 Pressure Regulators 4944.2 Valves 4974.3 Pressure Sensors 5004.4 Flow Meters 5014.5 Filters and Purifiers 5024.6 Vacuum Generators 5035.0 CYLINDER GAS DELIVERY SYSTEMS 5035.1 Enclosures (Gas Cabinets, Gas Storage Rooms, Etc.) 5035.2 Gas Panels 5055.3 System Monitoring 5085.4 System Control 5106.0 GAS CANDIDATES 5126.1 Ammonia 5126.2 Argon 5146.3 Arsenic Pentafluoride 5156.4 Arsine 5176.5 Boron Trichloride 5186.6 Boron Trifluoride 5206.7 Bromotrifluoromethane 5226.8 Chlorine 5246.9 Chloropentafluoroethane 5266.10 Chlorotrifluoromethane 5276.11 Diborane 5296.12 Dichlorodifluoromethane 5316.13 Dichlorosilane 5336.14 Disilane 5356.15 Germane 5366.16 Helium 5386.17 Hexafluoroethane 5396.18 Hydrogen 5416.19 Hydrogen Bromide 5436.20 Hydrogen Chloride 545

6.21 Hydrogen Fluoride 5476.22 Hydrogen Selenide 5496.23 Methyl Fluoride 5516.24 Nitrogen 5536.25 Nitrogen Trifluoride 5546.26 Nitrous Oxide 5566.27 Oxygen 5586.28 Perfluoropropane 5606.29 Phosphine 5626.30 Phosphorous Pentafluoride 5646.31 Selenium Hexafluoride 5666.32 Silane 5676.33 Silicon Tetrachloride 5686.34 Silicon Tetrafluoride 5706.35 Sulfur Hexafluoride 5716.36 Tetrafluoromethane 5736.37 Trichlorofluoromethane 5756.38 Trichlorosilane 5776.39 Tungsten Hexafluoride 579BIBLIOGRAPHY 580

11 Toxic Gas Monitoring 581

Paul C Manz

1.0 REQUIREMENT FOR CONTINUOUS TOXIC

GAS MONITORING 5811.1 Introduction 5811.2 Brief History 5822.0 PURPOSE OF A TOXIC GAS MONITORING SYSTEM 5833.0 FUNCTIONAL MODEL OF A TOXIC GAS MONITORING

SYSTEM 5873.1 Transport 5883.2 Analysis 5883.3 Identification 5943.4 Alarm 5973.5 Action 5984.0 SELECTION OF A TOXIC GAS MONITORING SYSTEM 5984.1 Single- or Multi-Point 5994.2 Gas Detection Technology 6044.3 Gas Detector Integration 6084.4 Role of Portable Gas Detectors 6125.0 FUTURE TRENDS 613REFERENCES 614

Index 616

1

Injury and Illness of

Semiconductor Workers: Experience and

“High Tech” industry, the semiconductor industry is characterized by rapidchanges, based on intense competition to place increasingly smaller micro-circuits on increasingly smaller substrate surfaces, with no loss in finalproduct “yield.” Layered on top of competitive production change is thenecessity to perform the crucial elements of manufacturing in isolated, ultra-clean wafer fabrication units Workers themselves are further isolated fromthe product being produced by wearing special “gowns,” hair covers andfacial masks They are protected from harmful exposures to toxic chemicalsand physical agents in ways that no large, manufacturing work force hasever been protected previously Only the aerospace and nuclear weaponsindustries provide similar worker exposure controls Yet, in all three ofthese industries, worker exposure controls were designed primarily to

maintain product purity in a working environment free of harmful nation Practically speaking, concerns for product purity have resulted also

contami-in worker protection

The wearing of personal protective clothing in semiconductor waferfabrication rooms has been coupled with sophisticated systems of ventila-tion and chemical/gas air monitoring and detection Alarms can be set atparts per million (ppm), or even parts per billion (ppb), to ensure thatsemiconductor employees are protected from harmful exposures resultingfrom releases of monitored chemical and gaseous substances From thisperspective, it must be understood that such controls on monitoring work-place air are absolutely essential in the wafer “fab.” Extremely toxic gases,such as arsine, phosphine and diborane have been in use in wafer fabricationsince the beginning of the industry The history of the industry is repletewith wafer fab evacuations based on real or suspected leaks of gases or ofsolvents Such evacuation episodes have become much less frequent intoday’s wafer fabs largely because of the lessons learned in design ofventilation systems, toxic gas/chemical handling and increasingly sophisti-cated air monitoring systems with continuous air sampling

From the standpoint of traditional workplace injury and illness tics, the U.S semiconductor industry has provided a model for workersafety and health protection The frequency of work-related accidents andexposures resulting in injuries and illnesses has been among the lowest in theU.S Figure 1 provides a graphic illustration of this experience comparedwith the private sector, all U.S manufacturing, and durable goods manufac-turing However, the industry has not been free of work injuries andillnesses, even though the rate of occurrence of such conditions has beenlow Nor has the industry been free of concern that more subtle healtheffects may be present.[1]

statis-In this chapter, we attempt to address both aspects of the U.S.semiconductor injury and illness experience The chapter will skim over thepast decade characterized by very low incidence rates of work injuries andillnesses among semiconductor workers to focus, instead, on stratification

of work injuries and illnesses experienced by this work force during 1993(provided by the U.S Bureau of Labor Statistics and the Occupational HealthSystem of the Semiconductor Industry Association).[2] Because of a majorconcern for the reproductive health of workers which surfaced in thisindustry during the middle 1980’s, a review of three, independent epidemio-logic investigations is presented and the results discussed

Finally, it must be emphasized that the U.S semiconductor industry has represented a unique modeling opportunity for public health research Although major companies within the industry have always been highly competitive, these same companies have formed several organizations de- signed to facilitate information and data exchange of a noncompetitive nature which have relevance to the safety and health of the semiconductor work force These organizations include SEMATECH, the Semiconductor Safety Association (SSA), and the Environmental Safety and Health Com- mittee of the Semiconductor Industry Association (SIA) The geographic

“compactness” of the industry in the “Silicon Valley” of Northern Califor- nia in the 1980’s made possible the development of the Occupational Health System (OHS), which will be discussed later Without the ability to

maintain a close, ongoing relationship with key members of the industry’s safety and health community (often involving ad hoc meetings on short

notice) a work injury and illness surveillance system such the OHS might not have been possible

Figure 1 Comparative annual incidence rates for Occupational Health System, U.S semiconductor industry, durable goods, and all manufacturing (1983-95)

2.0 REVIEW AND DISCUSSION OF SEMICONDUCTOR INDUSTRY WORK INJURIES AND ILLNESSES

During the past several decades the primary indicator of the safetyand health experience of the American work force has been the incidence ofwork-related injuries and illnesses as published annually by the U.S Bureau

of Labor Statistics (BLS).[3] These incidence rates (calculated as theaverage number of new injury or illness cases per 100 full-time equivalentemployees per year) have provided a standardized annualized statistic forcomparing the overall work injury and illness experience of workers invarious industry sectors

Prior to 1972 (the initial BLS survey year), the only significantsources of data concerning semiconductor worker safety and health wereindividual states’ workers’ compensation records Because of the dearth ofdata concerning worker health prior to 1972, the growth of the industryduring the 1970’s and the many manufacturing process changes which havebecome a signature of the industry, historical data concerning injuries andillnesses among semiconductor workers prior to 1972 can be consideredfairly irrelevant

Hence, the safety and health experience of the U.S semiconductorindustry work force has been closely tied to the annual incidence of workinjuries and illnesses as calculated by the BLS rate for this industry Figure 1compares annual incidence rates for various industry sectors with the ratesfor the semiconductor industry during the period 1983–1995

Beginning in 1982, the primary trade association of the U.S ductor industry (Semiconductor Industry Association—SIA) has sponsored

semicon-the development and maintenance of semicon-the Occupational Health System (OHS).

This system provides detailed data analyses of pertinent work injury andillness case variables on an annual basis for the semiconductor industry.Approximately one-quarter to one-third of the U.S semiconductor industryparticipates in the OHS program on a year-to-year basis Prior to 1982, theonly significant data concerning the safety and health experience of thenation’s semiconductor work force were those published annually in theBLS surveys, as discussed above

Other indicators of the safety and health status of semiconductorworkers have been reports of surveys (Health Hazard Evaluations) per-formed by the National Institute for Occupational Safety and Health (NIOSH),

a sprinkling of papers published in the open scientific literature and ings of symposia associated with environmental and worker safety and

proceed-health issues.[4][5] In addition, an annual meeting of semiconductor safety,health and environmental professionals sponsored by the SemiconductorSafety Association (SSA) has provided timely presentations concerningworker safety and health issues.

Finally, as stated above, several epidemiologic studies have beenperformed during the past decade which focus on reproductive healthconsequences of employment in the semiconductor industry

These sources of data and information concerning semiconductorworker injuries and illnesses are discussed in the following sections of thischapter to present a contemporary review of the current status of the safetyand health of this industry’s work force

2.1 Work Injury and Illness Statistical Program of U.S BLS

Because of both the historic and contemporary importance of the BLSAnnual Surveys of Work-Related Injuries and Illnesses, with respect tounderstanding the safety and health status of U.S semiconductor workers, asummary discussion of this program is in order

2.2 OSHA Recordkeeping System

The Occupational Safety and Health Act of 1970 (OSH Act) createdtwo new federal agencies: the Occupational Safety and Health Administra-tion (OSHA) within the U.S Department of Labor and the National Institutefor Occupational Safety and Health (NIOSH) within the U.S Department

of Health and Human Services The role of OSHA was to promulgate andenforce national workplace standards designed to protect the safety andhealth of the American worker, while the role of NIOSH was to sponsorresearch, train occupational safety and health professionals and recommendcriteria for workplace standards to OSHA

The OSH Act mandated the Secretary of Labor with responsibility fordeveloping and maintaining a national system for collection and analysis ofwork injury and illness statistics In 1971 (the initial year that the OSH Acttook effect), the Secretary of Labor delegated this responsibility to theBureau of Labor Statistics (BLS), within the Department of Labor Sincethat time BLS has performed a national Annual Survey of OccupationalInjuries and Illnesses, while OSHA has retained responsibility for enforcingcompliance with the recordkeeping provisions of the Part 1904 of the OSHAregulations

In 1971, OSHA promulgated the initial recordkeeping requirements

at Title 29 CFR Part 1904 These recordkeeping regulations requiredemployers with eleven or more employees to maintain an annual log of workinjuries and illnesses, except for minor, first aid injuries The log form isentitled “Log and Summary of Occupational Injuries and Illnesses,” (OSHA

No 200 form) and is required to be maintained by employers in allworkplace establishments covered by the OSH Act Only certain “lowhazard” industries are specifically exempted from the annual recordkeepingrequirements of the regulations The exempted industries include certainretail industries, all finance, insurance, and real estate industries and certainservice industries However, some employers in each exempted industry arerequired to maintain the OSHA-200 log from time to time to provide astatistical sample for the Annual Surveys performed by BLS

In addition to the OSHA-200 log itself, the recordkeeping regulationsrequire completion of a supplemental record for each work injury and illnesscase recorded on the log The supplemental record contains more detailconcerning the characteristics of the recorded case, included demographicvariables Employers are provided the choice of completing a separateSupplementary Record of Occupational Injuries and Illnesses (OSHA No

101 form) or of substituting an alternate form (e.g., Workers’ tion reporting form) as long as the alternate form contains equivalent dataand information

Compensa-The Annual BLS Survey is performed by selecting a representativesample of employers from all industries according to Standard IndustrialClassification (SIC) code and employment size (“establishment size”) andrequiring the selected employers to copy annual totals of cases and days oflost and restricted work to a survey form Beginning in 1992, the AnnualSurvey began to require detailed data from the supplementary data form(OSHA-101 or equivalent) for a sample of cases involving lost days awayfrom work The data collected by BLS during the Annual Survey arecompiled into simple, summary statistics and published approximately twoyears following the year of occurrence The published statistics include theaverage annual incidence of cases of work injuries and illnesses which haveoccurred per 100 full-time equivalent workers per year by major industrydivision and 4-digit SIC code Also, incidence rates associated with lost andrestricted workdays cases are published

Hence, the BLS Annual Surveys provide the U.S public with ized frequency statistics concerning cases and work loss time associatedwith employee injuries and illnesses In 1992, the Annual Survey began

annual-providing more detailed data concerning case and demographic tics of cases involving lost days away from work.

characteris-2.3 Usefulness of BLS Survey to U.S Semiconductor Industry

In evaluating the usefulness of the BLS recordkeeping system withrespect to a particular industry, it is important to understand the limits ofthat system

Firstly, the system is sustained by the thousands of the nation’semployers who are required (by OSHA regulation) to maintain the OSHA-

200 log and OSHA-101 (or equivalent form) supplemental data form.Despite OSHA’s view that the records provide employers with a valuableresource for analyzing the work injury and illness experience of their workforce, many employers view the system as an encumbrance or, worse, arequired nuisance This assessment of the system on the part of employers

is unfortunate, but understandable The reasons for this viewpoint byemployers are many and are varied It is sufficient in this context simply tounderstand that the system has been maintained over the past two decades

by individuals who have little at stake in its success and who would carelittle if it completely failed The fact that organized labor has, likewise,placed little importance on increasing the effectiveness of the OSHA/BLSrecordkeeping system simply underscores this perspective Hence, the roots

of the present system provide little support other than what is mandatorilyrequired by OSHA regulation For this reason, only the required minimaleffort is expended by employers to maintain the system’s required records.Even that minimal effort often falls short in maintaining the detailedsupplemental case form (OSHA-101 or equivalent)

Secondly, employers view the system as a regulatory enforcementtool Because OSHA compliance inspections normally begin with a review

of the OSHA-200 log, employers have long regarded their OSHA-200 log

as a self-incriminating document This viewpoint became entrenched when

it was widely understood that the course of an OSHA inspection could hinge

on whether the establishment’s lost workday experience was consideredexcessive, compared to similar companies in the same SIC (StandardIndustrial Classification) code This situation tends to place undue empha-sis on maintaining a low company profile with respect lost workdays andlost workday cases Hence, company recordkeeping policies and adequateemployee recuperation associated with work loss can become cloudedissues

Thirdly, OSHA recordkeeping mechanics tend to complicate what is,

in essence, really a very simple procedure Requirements for (i) recording distinctions between injuries and illnesses on the OSHA-200 log, (ii) for placing X’s in various columns on the log and (iii) for carrying forward

individual sheet totals of cases and work loss days to annual totals arefraught with possibilities for errors

From this perspective, it may seem incongruous that these recordscould be of prime, practical significance to estimating the work injury andillness experience of the U.S semiconductor industry, much less the nation’swork force However, because the BLS recordkeeping system is consideredcredible by the federal and individual state governments, and because it isused both to target OSHA inspections and to determine the work injury andillness experience of employees in individual workplaces, it must be included

in any employer’s plan of injury and illness surveillance

2.4 Occupational Health System (OHS)

In 1991, the Board of Directors of the Semiconductor IndustryAssociation (SIA) sponsored development of the Occupational Health Sys-tem (OHS) The primary purpose of the OHS was to document the workinjury and illness experience of the U.S semiconductor industry work force

on an annual basis The OHS was supported by participating companies on

an annual fee basis

The primary components of the OHS include:

1 Occupational Title Directory

The Occupational Title Directory was designed to provide

a system of uniform coding of cases from participatingcompanies based on common jobs The Directory containsapproximately 65 occupations common to the U.S.semiconductor industry work force Although the sourcefor the Directory was the U.S Bureau of the Censusclassification of occupations, the Directory wasspecifically tailored for use in the OHS and includes adisproportionate number of jobs for engineers andtechnicians, compared with the source document

2 Case characteristic codes

A series of codes was developed to classify casecharacteristics of worker injuries and illnesses according to:

• Type of accident or exposure or event

• Source of injury or illness

• Nature of injury or illness

• Part of body affected

• (Cause of accident or exposure—optional)

All work injury and illness cases submitted for inclusion

in the OHS database are coded except for “cause ofaccident or exposure” code This latter code is, presently,optional in the OHS

• Date of injury or illness

• (Time of injury or illness—optional)

• Employee name

• Employee SSN

• Employee Number

• Number of work loss days (away from work)

• Number of restricted workdays

• Company/facility ID Code

• Department/work division

• OSHA classification as to “injury” or “illness”

5 Computerized management information system

A computerized management information system wasdeveloped to manage the OHS database, and tailoredversions of this program are made available for use byparticipating companies Companies which have eitherpurchased or developed their own computer programs tomanage work injury and illness data, or which performsuch analyses manually, are required to provide computerfiles of coded cases or hard copies of coded data Datafrom the OHS have been included along with comparabledata from the BLS 1993 Survey in Figs 1–14

2.5 Work Injury and Illness Experience of Semiconductor Workers

Annual incidence rates for OSHA-recordable work injuries and nesses for various U.S industry sectors during the period 1983–1995 arepresented in Fig 1 These rates (average numbers of cases per 100 full-timeequivalent workers per year) compare all manufacturing and durable goodsmanufacturing with semiconductor manufacturing and with the OHS data-base for the same time periods The primary distinction in these rates isbetween the incidence of cases for all manufacturing and durable goodsmanufacturing compared with rates for both semiconductor manufacturing(BLS) and the OHS database During this period, incidence rates forsemiconductor manufacturing have been approximately one-third of therates for durable goods manufacturing In fact, during the past decade thesemiconductor industry has experienced some of the lowest incidence rates

ill-of work injuries and illnesses in the durable goods manufacturing sector.However, the practical significance of these rate comparisons isseriously limited As discussed in the section of this chapter dealing with theBLS recordkeeping system, these rates provide no information beyond therate statistic, itself Unfortunately, rate comparisons (based on publishedBLS rates) have been used widely during the past several decades assurrogates of the status of worker safety and health of entire industrysectors, individual companies, company divisions etc Although suchcomparisons—in the broadest sense—are justified, they tend to mask pos-sible underlying problems Only the composite experience is documented inthe BLS published annual rates, with no stratification of the data beyond the4-digit SIC code Of course, from a relative risk standpoint, it is possible to

identify industry sectors, companies, divisions, etc., which differ, cantly, from calculated “norms.”

signifi-Fortunately, beginning in 1992, the U.S Bureau of Labor Statistics(BLS) began publication of a new series of data analyses based on detailedcoding of OSHA-recordable cases involving days away from work Dataobtained directly from BLS2 have been used to produce a series of figures(Figs 2–14) which present direct comparisons of these data as they pertain

to the experience of employees in the U.S semiconductor industry during

1993 Although these data cannot be thoroughly analyzed at presentbecause of the limited access afforded by BLS, as a whole they providemuch greater clarity concerning the work injury and illness experience ofU.S semiconductor workers than has been available previously A discus-sion of these data is presented below With the exception of Fig 5(associated with race/ethnic characteristics) each figure compares the lostworkday* case experience for the private sector, all manufacturing, semi-conductor manufacturing and the OHS database

The incidence of cases with days away from work in 1993 for theindustry sectors being compared in these figures was:

• Private sector 3.0 cases per 100 workers

• All manufacturing 3.5 cases per 100 workers

• Semiconductors 1.2 cases per 100 workers

Figure 2 compares the distribution of lost workday cases according tothe primary, major occupation of the affected worker In the absence ofincidence rates, these data illustrate a similar pattern of cases for theindustry sectors depicted For all sectors, the greatest proportion of casesoccurred among workers employed as operators, fabricators or laborers.The OHS has documented that the greatest number of cases during the pastdecade have involved wafer fabrication employees, although the incidence

of cases for this group has been only slightly in excess of the rate for thesemiconductor industry, as a whole (e.g., 4.0–5.0)

The comparative distribution of lost workday cases stratified byemployee age at time of accident or exposure is presented in Fig 3 Arelated set of data is presented in Fig 4, associated with the length ofemployee service with the employer In both figures, semiconductor work-ers predominate in the older worker groups (Fig 3) and in the groups withmost service with the employer (Fig 4) The reasons for greater proportions

of semiconductor workers in the older/longer service groups are, probably,

* The terms lost workdays and lost workday cases will apply only to cases with days away

from work in this chapter

more likely associated with greater proportions of employees (“at risk”) inthese two categories in the semiconductor industry That is, it is possiblethat the semiconductor industry has a relatively greater proportion of olderemployees, which would also indicate a greater number of workers withmore experience However, in the absence of incidence rates, it is not possiblecompletely to rule out a greater risk of injury or illness for these workers.

Figure 3 Comparative distribution of lost workday cases by employee age group—1993 Figure 2 Comparative distribution of lost workday cases (cases with days away from work)

by employee occupation—1993.

Figure 4 Comparative distribution of lost workday cases by length of service with

employer —1993.

In Fig 5, the proportional distribution of lost workday cases ing to employee race/ethnic group is presented (The OHS does not codecases according to this variable.) With respect to the U.S semiconductorindustry, greater proportions of injuries or illnesses occurred among His-panic and Asian/Pacific Islander employees in comparison with other race/ethnic groups of semiconductor workers In the case of Asian/PacificIslander employees, a near fourfold excess of lost workday cases wasdocumented for this group of semiconductor workers in 1993, comparedwith the other race/ethnic groups Again, an absence of incidence rates byrace/ethnic group precludes definitive analyses of these differences It ismost probable that the excess of cases is more reflective of greater numbers

accord-of workers in these race/ethnic categories employed in the semiconductorindustry There is no reason to believe that race or ethnicity would beexpected to place semiconductor workers at proportionately greater risk ofinjury or illness

Figure 5 Comparative distribution of lost workday cases by race or ethnic group—1993.

Figure 6 examines differences in the distribution of days away fromwork for these industry sectors Compared with the private sector and allmanufacturing, both the semiconductor industry and the OHS databasereported greater proportions of cases involving only one or two days wayfrom work This experience tends to indicate that lost workday casesinvolving semiconductor workers are less severe than for workers in theother comparison industry sectors

Figures 7 and 8 compare the lost workday experience of tor workers with the private sector and with all manufacturing with respect

semiconduc-to event or exposure (also stated as “type for accident or exposure”) Fromthe viewpoint of proportional lost workday case distribution (Fig 7), theU.S semiconductor industry and the OHS database documented greaterproportions of cases associated with overexertions and harmful exposuresthan the private sector or all manufacturing However, in Fig 8, whichillustrates the incidence of cases with days away from work, the incidencerate for most categories was much less for the two semiconductor groupsthan for the private sector or all manufacturing Cases involving overexertionsamong semiconductor workers were less than one-half the rate for workers

in the rest of the manufacturing sector The harmful exposure category(primarily associated with exposures to chemical substances) was equiva-lent among all four groups

Figure 7 Comparative distribution of lost workday cases by event or exposure—1993.

Figure 6 Comparative Distribution of lost workday cases by numbers of days away from

work—1993.

SOURCE: Annual Survey, US DOL, 1993, & OHS Annual Survey, 1993

Figure 8 Comparative incidence of lost workday cases by event or exposure—1993.

Comparative distributions of lost workday cases according to source

of injury or illness are presented in Figs 9 and 10 In Fig 9, the twosemiconductor groups predominate in the source categories associated withchemicals In addition, the U.S semiconductor group had greater propor-tions of lost workday cases associated with containers and “worker motion/position” (i.e., ergonomic cases) A large difference was observed betweenthe two semiconductor groups with respect to “machinery” as a sourcecategory The OHS database reported an almost threefold greater propor-tion of cases for this group than for the U.S semiconductor industry, as awhole It is possible that this difference was associated with better sourcedefinition available to the OHS than is available to the BLS state agencieswhich perform case coding In Fig 10, the influence of low overallincidence rates for the two semiconductor groups is once again observed.Lost workday case rates for both semiconductor groups are below those forthe private sector and all manufacturing with the exception of a slightlyhigher rate for the OHS database with respect to the “chemicals” sourcecategory

Figures 11 and 12 compare proportions of cases and incidence rates,respectively, associated with the nature of injuries or illnesses among thefour groups In Fig 11, both semiconductor groups projected higherproportions of cases associated with strains or sprains and with chemical

burns compared with the other two groups In addition, the U.S ductor group exhibited a greater proportion of carpal tunnel syndrome(CTS) than the private sector The higher proportion of lost workday casesassociated with strains or sprains among semiconductor workers is resolved

semicon-in Fig 12 In this figure, the rates for the two semiconductor groups wereless than one-half of the rates for both the private sector and for allmanufacturing in 1992 The incidence of chemical burns was slightlyhigher for semiconductor workers, but was very low for all comparisongroups The incidence of CTS among U.S semiconductor workers was lessthan one-half the rate for all manufacturing

In Figs 13 and 14, respectively, the distribution and incidence ofcases involving days away from work is illustrated according to part of bodyaffected Proportional distributions of cases were similar among all fourgroups (Fig 13) with the exception of greater proportions of cases amongthe two semiconductor groups associated with body system(s) These caseswere consistent with the observation of greater numbers and rates associatedwith “chemicals” as a source category in Figs 9 and 10, respectively InFig 14, although the incidence of cases involving body systems was low forall comparison groups, the rates for semiconductor workers remainedslightly elevated This slight difference may be related to greater controlover accuracy of data coding afforded by the OHS

Figure 9 Comparative distribution of lost workday cases by source of injury or illness—

1993.