Exposure Assessment for Retrospective Follow-Up Studies of
Semiconductor and Storage Device Manufacturing Workers
Robert Herrick et. al.
APPENDIX – DETAILED WORK GROUP SPECIFICATIONS
1. Semiconductor Fabrication. This group is composed of “semiconductor manufacturing jobs.”
These jobs include the semiconductor process steps, oxidation, diffusion, ion implantation,
chemical vapor deposition, etching (wet and dry), metallization, photolithography and epitaxi.
Jobs would include those such as operators, production control, various technicians, engineers,
supervisors, inspectors and managers. Potential exposures include acids, bases, solvents
(including glycol ethers, aromatic solvents, chlorinated solvents, freons, ketones and alcohols),
toxic gases such as phosphine, arsine, diborane and metals such as antimony, arsenic, nickel and
gold. Exposures to physical agents such as ultraviolet light, radiofrequency radiation and soft xrays are also possible.
2. Packaging. Jobs in this group include those producing ceramic substrates used to mount
multiple chips producing devices with various functions, e.g., logic or CPU. The process steps are
very similar to semiconductor manufacture, including photolithography, chemical vapor
deposition, planarization, and many cleaning steps. Potential exposures to members of this Group
would include acids, bases, solvents, heavy metals, metals, amorphous silica and
toxic/corrosive/pyrophoric gases.
3. Facilities/Quality Assurance/Laboratories/EH&S. This group includes jobs in facilities
engineering, plant engineering, plant maintenance, environmental health and safety, laboratory
workers and quality assurance, engineering and control. Because the tasks these workers perform
can change on an inter/intra-day basis their exposure patterns can vary widely. Due to the nature
of their work they have the potential for significant peak exposures. Potential exposures to
members of this group include any agent at the site.
4. ChemMix. This group contains the workers responsible for preparation and delivery of the
chemicals used at the site. These workers handle chemicals throughout the day. They also work
with larger quantities of chemicals than the other groups. These workers may be selected as
members of the chemical spill cleanup teams. These workers have potential for exposure to a
wide range of manufacturing and research chemicals including organic solvents (examples are
glycol ethers, chlorinated solvents, aromatic solvents, freons, ketones, tetramethylammonium
hydroxide and hexamethyldisilizane), acids such as hydrofluoric, sulfuric, nitric, acetic,
phosphoric, hydrochloric, chromic, bases such as potassium hydroxide, ammonium hydroxide, and
oxidizers such as hydrogen peroxide, sodium persulfate, chromates and perchlorates. Chemicals
are then transported to the end user via hand-carts or they are delivered through piping.
5. Masking. Workers in this group produce masks that contain the pattern that is printed on the
silicon wafer. Mask production has changed significantly over the years; however, it has remained
a chromium-based process. Potential exposures in this group would include solvents (including
glycol ethers), chlorinated solvents, aromatic solvents, acids, radiofrequency radiation, ultraviolet
light and “yellow” lights. Masking operations are conducted in cleanrooms. Some of the
operations have very high cleanroom requirements (Class 1-10) while other Masking tasks can be
conducted in Class 10,000 cleanrooms.
6. Research and Development. Workers in this group generally work with the widest range of
materials because their goal is to develop new processes or products. For example, a researcher
may experiment with a chemical or a physical agent such as radiation, then find out that it does
not work and move to another. Another characteristic of these operations that might be that
controls are less sophisticated because there is less time to adapt the facility to the new operation
or there may be unforeseen issues with the new agents.
7. Field Service. There are workers who are assigned to a particular site, e.g., East Fishkill but
may work at another location or their work may involve travel and exposure to hazards at a
customer site. The potential exposures to members of this group are different than any of the other
Groups because they may be more related to the customer site they are visiting than to those of the
employer.
8. Chemical Mechanical Planarization (CMP) and Backlap. At various points in the production
process, silicon wafers and other substrates need to be planarized or have their thickness reduced.
CMP (Chemical Mechanical Planarization or Chemical Mechanical Polishing) and an older
process called “backlap” are processes that remove material from a substrate using a slurry of
aluminum oxide, silica or other abrasive. After lapping, substrates are often etched in a solution of
nitric and acetic acid or in sodium hydroxide. Polishing is often conducted with a slurry of silica
powder and a strong base such as sodium hydroxide in deionized water. The newer CMP methods
contain a wider variety of chemicals in the slurry. These jobs have potential exposure to acids,
bases, alumina, silica and potential gaseous emissions from the lapping and polishing process.
9. Maintenance (Process and Equipment). Because the production processes are complex and
require sophisticated equipment there are skilled technicians and engineers assigned to maintain
and repair line equipment. These jobs are unique and may have exposure to any of the process
chemical and physical agents. These personnel work in close proximity to the potential exposure
sources. In many situations they bypass safety interlocks and work in situations where the
equipment may be down or failed because of a release of a chemical agent. In semiconductor and
packaging manufacturing, the work sometimes takes place in the cleanroom, and, in many cases,
in the maintenance chaise/aisle or in the maintenance area adjoining the semiconductor fabrication
area. These workers may also be responsible for cleaning the internal parts of the equipment that
may be contaminated with hazardous materials, e.g., elemental arsenic plated out inside an ion
implanter. This group is highly skilled technical workers but have the potential for significant
exposures and exposure to a wide variety of chemical and physical agents. They also experience
wide variations in potential exposures from day to day. In addition, equipment engineers of all
types are included in this group because they often work with equipment to determine how it will
be installed in the manufacturing area.
10. Office/Other Support. Some jobs such as accountants, marketing personnel, lawyers, computer
programmers, computer operators, telecommunications personnel, administrative assistants,
secretaries, financial analysts, personnel/human resources, third level managers and higher, plant
security, medical personnel etc have little to no contact with production operations and related
potential exposures. These jobs would not be affected by changes in manufacturing over time
because they do not enter those work areas. This group may have higher potential exposure to
certain building related hazards such as asbestos, molds or other indoor air quality issues
compared to those that worked in cleanrooms.
11. Other Manufacturing. If the site has other than semiconductor or packaging manufacturing,
e.g., module assembly, computer system assembly/burn-in, monitor manufacture, flat screen
manufacture, circuit board production, system assembly or the like, these jobs will be placed in a
separate category. The range of potential exposures to chemical, biological and physical agents
would be less than either semiconductor or packaging operations. Some of the potential exposures
could include radio-frequency radiation, cleaning solvents, degreasing operations and marking
inks.
12. Plating. Electroplating of gold, nickel, copper and a number of other metals is a process step in
the manufacturing of many types of electronic devices. Electroplating uses cyanides, heavy metals
a variety of acids and other chemicals. Plating operations take place in a wide range of
environments ranging from open surface tanks where the product is moved from tank to tank by
hand to enclosed automated lines with electronic barriers, which ensures that workers do not enter
the enclosure while the plating line is operating.
13. Test/Probe/Dicing/Slicing/Die Removal/Wire Bonding. When the wafer has completed its
processing it can contain several hundred actual devices (die). Each die needs to be tested to make
sure that it is functional. If the die is not functional it is often marked with a dye material (usually
an epoxy) so that it can be removed from the production process. This operation is generally
conducted in a clean room but of a lower class than those of masking or semiconductor
fabrication. Potential exposures of this Group include inks, epoxies, plastics, and solvents such as
isopropyl alcohol. In some of the newer processes ozone is used to prep some of the package
surfaces before marking. The operations do not involve significant exposures to chemical or
physical agents.
14. Cafeteria/Food Service. This group contains all food service workers. Food service workers
have exposures to many physical hazards such as heat, cold, sharp objects and biological agents.
15. Unassigned. This group is composed of those DDJs where the job name, department name and
division name did not provide sufficient information to assign a group or exposure status.
Work Group Descriptions For San Jose
Because San Jose operations were quite different from East Fishkill and Burlington there were 19
work groups necessary for San Jose. A result of this difference might be the size of the worker population
in work group 9 (Process and Equipment Maintenance) at San Jose. Subjectively, these jobs would seem to
be needed in greater numbers at San Jose than we found. In East Fishkill and Burlington the job names and
department names appeared to be identified more easily. The low number of workers classified as Process
and Equipment Maintenance at San Jose could be due to our inability to identify the department name
and/or the job name as belonging to this work group (or it could be that these services were provided in a
different manner, e.g., not organized by department).
The number of work groups at San Jose increased to 19 reflecting the different types of
work/exposures that potentially occurred there. The exposure groups for San Jose are provided in Table V
followed by the exposure group descriptions. A subjective but important difference between San Jose and
the other two study sites was that San Jose seemed to have job names and department names that were not
as descriptive as those at East Fishkill and Burlington. This made classification into work groups more
challenging.
1. Disk Manufacturing. This group contains workers directly involved in manufacture of disks for data
storage. Disk Manufacturing began as a polymer film process and in the early 1990s began to switch
over to metallic thin films. The polymer film manufacturing process utilized a variety of chemicals and
involved potential for exposure to acetone, isopropyl alcohol, kerosene, freon, hydrofluoric acid,
xylene, ethyl amyl ketone, isophorone, chromate compounds, alumina, iron oxide and sulfuric acid.
The newer metallic thin film process involves fewer potential exposures to chemicals.
2. Head Wafer/Tape Head Manufacturing. This group contains workers directly involved in
manufacture of head wafer and tape head. These two operations are combined because of similarities
in chemicals used and operations, e.g., photolithography. Main potential exposures to people in this
group are to solvents like isopropyl alcohol, acetone, freon degreasers (e.g., Detricks) and other agents
such as glycols, urethanes, adhesives, nickel, iron, and copper.
3. Facilities/Laboratories/EH&S. This group includes jobs in facilities engineering, plant engineering,
plant maintenance, environmental health and safety, and laboratory workers. The tasks for this group
are similar to Group 3 at East Fishkill and Burlington, however the associated exposures may be
different because of differences in the manufacturing processes at San Jose.
4. ChemMix. This group contains the workers responsible for preparation and delivery of the chemicals
used at the site. The tasks for this group are similar to Group 4 at East Fishkill and Burlington,
however the associated exposures may be different because of differences in the manufacturing
processes at San Jose.
5. Head Fabrication. Workers in this group are directly involved in head fabrication and have potential
for exposure to coolants, slurries, cleaners and solvents including acetone, and isopropyl alcohol,
cellosolves, methylene chloride, n-methyl pyrrolidone.
6. Research and Development. Workers in this group generally work with the widest range of materials
because their goal is to develop new processes or products. The tasks for this group are similar to
Group 6 at East Fishkill and Burlington, however the associated exposures may be different because of
differences in the manufacturing processes at San Jose.
7. Field/Customer Service. There are workers who are assigned to a particular site, e.g., San Jose but
may work at another location or their work may involve travel and exposure to hazards at a customer
site. The potential exposures to members of this group are different than any of the other Groups
because they may be more related to the customer site they are visiting than to those of the employer.
8. Head Suspension/HDA/Box. These operations are light manufacturing and do not involve significant
chemical usage. The main exposures to workers in this group are adhesives, isopropyl alcohol, acetone
and freon. Other potential chemical exposures include Andoc C, Triton X, Alfonics 610-50 .02%,
loctite adhesives, epoxies, urethane adhesives and alcohol.
9. Maintenance and Engineering (Process and Equipment). Because the production processes are
complex and require sophisticated equipment there are skilled technicians and engineers assigned to
maintain and repair line equipment. The tasks for this group are similar to Group 9 at East Fishkill and
Burlington, however the associated exposures may be different because of differences in the
manufacturing processes at San Jose.
10. Office/Other Support. Jobs in this group (accountants, marketing personnel, lawyers, etc) are
comparable to group 10 at East Fishkill and Burlington.
11. Other Manufacturing. Other manufacturing than that covered in Groups 1,2,5,8, e.g., System
Manufacturing, card manufacturing, circuit board production is included in group 11. The tasks for this
group are similar to Group 11 at East Fishkill and Burlington, however the associated exposures may
be different because of differences in the manufacturing processes at San Jose.
12. Plating. The tasks for this group are similar to Group 12 at East Fishkill and Burlington, however
the associated exposures may be different because of differences in the manufacturing processes at San
Jose.
13. Test/Probe/Dicing/Slicing. When the disk/head/tape head etc. has completed its processing each
die needs to be tested to make sure that it is functional. The tasks for this group are similar to Group 13
at East Fishkill and Burlington, however the associated exposures may be different because of
differences in the manufacturing processes at San Jose.
14. Cafeteria/Food Service. The tasks and associated exposures for this group are similar to Group 14
at East Fishkill and Burlington.
15. Unassigned. This group is composed of those DDJs where the job name, department name and
division name do not provide sufficient information to assign a group or exposure status.
16. Assembly. The members of this group are workers who assemble any of the devices produced by
the other groups. The potential exposure to chemical or physical agents is small but still exists.
17. Quality Control/Quality Assurance. These workers monitor the processes, equipment, personnel
and product, to ensure that the products of acceptable quality are produced. The job may involve
collecting samples from the manufacturing line, observing workers, or checking operational
specifications for equipment, final inspection of the components and subcomponents. They are
potentially exposed to manufacturing chemicals.
18. VLSI/Semiconductor Fabrication. This group is composed of “semiconductor manufacturing jobs."
These jobs include the semiconductor process steps, oxidation, diffusion, ion implantation, chemical
vapor deposition, etching (wet and dry), metallization, photolithography and bubble manufacturing.
Jobs would include those such as operators, production control, various technicians, engineers,
supervisors, inspectors and managers. Potential exposures include acids, bases, solvents (including
glycol ethers, aromatic solvents, chlorinated solvents, freons, ketones and alcohols), and toxic gases
such as phosphine, arsine, diborane and metals such as antimony, arsenic, nickel and gold. Exposures
to physical agents such as ultraviolet light, radio frequency radiation and soft x-rays are also possible.
Semiconductor Test, probe, wire bond, encapsulation are not part of this group. Semiconductor Quality
Assurance and Quality Control are included in this Group.
19. Masking. Masks contain the pattern that is printed on a substrate (silicon wafer). The tasks and
associated exposures for this group are similar to Group 5 at East Fishkill and Burlington.