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International Journal of Occupational and Environmental
Health
ISSN: 1077-3525 (Print) 2049-3967 (Online) Journal homepage: http://www.tandfonline.com/loi/yjoh20
Chemical use in the semiconductor manufacturing
industry
Sunju Kim, Chungsik Yoon, Seunghon Ham, Jihoon Park, Ohun Kwon,
Donguk Park, Sangjun Choi, Seungwon Kim, Kwonchul Ha & Won Kim
To cite this article: Sunju Kim, Chungsik Yoon, Seunghon Ham, Jihoon Park, Ohun Kwon,
Donguk Park, Sangjun Choi, Seungwon Kim, Kwonchul Ha & Won Kim (2018): Chemical use in the
semiconductor manufacturing industry, International Journal of Occupational and Environmental
Health, DOI: 10.1080/10773525.2018.1519957
To link to this article: https://doi.org/10.1080/10773525.2018.1519957
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Chemical use in the semiconductor manufacturing industry
Sunju Kim
a
, Chungsik Yoon
a
, Seunghon Ham
b
, Jihoon Park
a
, Ohun Kwon
a
, Donguk Park
c
,
Sangjun Choi
d
, Seungwon Kim
e
, Kwonchul Ha
f
and Won Kim
g
a
Department of Environmental Health Science and Institute of Health and Environment, Graduate School of Public Health, Seoul
National University, Gwanak-gu, Seoul, Republic of Korea;
b
Department of Occupational and Environmental Medicine, Gil Medical
Center, Gachon University College of Medicine, Namdong-gu, Incheon, Republic of Korea;
c
Department of Environmental Health, Korea
National Open University, Jongno-gu, Seoul, Republic of Korea;
d
Department of Occupational Health, Catholic University of Daegu,
Gyeongsan-si, Republic of Korea;
e
Department of Public Health Environmental Health, Keimyung University, Dalseo-gu, Daegu, Republic
of Korea;
f
Department of Environmental Health, Changwon National University, Gyeongsangnam-do, Republic of Korea;
g
Wonjin
Institute, Jungnang-gu, Seoul, Republic of Korea
ABSTRACT
Background: The semiconductor industry is known to use a number of chemicals, but little is
known about the exact chemicals used due to the ingredients being kept as a trade secret.
Objectives: The objective of this study was to analyze chemical use using a safety data sheet
(SDS) and chemical inventory provided by a major semiconductor company, which operated
two factories (A and B).
Methods: Descriptive statistics were obtained on the number of chemical products and
ingredients, photoresists, and carcinogens, classified by the International Agency for
Research on Cancer (IARC), as well as trade secret ingredients. The total chemical use per
year was estimated from chemical inventories mass (kg).
Results: A total of 428 and 432 chemical products were used in factories A and B, respec-
tively. The number of pure chemical ingredients, after removing both trade secret ingredients
and multiple counting, was 189 and 157 in factories A and B, respectively. The number of
products containing carcinogens, such as sulfuric acid, catechol, and naphthalene was 47/428
(A) and 28/432 (B). Chemicals used in photolithography were 21% (A) and 26% (B) of all
chemical products, and more than 97% among them were chemicals containing trade secret
ingredients.
Conclusions: Each year, 4.3 and 8.3 tons of chemicals were used per person in factories A and
B, respectively. Because of the high level of commercial secrecy and the use of many
unregulated chemicals, more sustainable policies and methods should be implemented to
address health and safety issues in the semiconductor industry.
ARTICLE HISTORY
Received 24 April 2017
Revised 3 September 2018
Accepted 3 September 2018
KEYWORDS
Semiconductor; chemical;
SDS; trade secret
ingredients;
photolithography
Introduction
The semiconductor industry, which is characterized by
high levels of technological integration, has changed
rapidly. A variety of chemical substances are used in
the semiconductor manufacturing process. The num-
ber and amount of chemicals is increasing because of
rapid technological developments in the industry [1].
Although most chemical substances used in a semi-
conductor manufacturing factory are known to be
harmful [2–5], it is difficult to obtain hazard informa-
tion for all chemicals because of the use of trade
secrets. In particular, it is difficult to obtain informa-
tion on the chemical content, chemical abstract service
(CAS) number, ingredients, and hazards of these che-
micals because of patents and trade secrets.
Workers in a semiconductor factory are likely to
be exposed to carcinogens and reproductive materials
[3,6–8]. In the 1980s, studies of carcinogens and
chemicals used in the semiconductor industry that
are harmful to workers’reproductive health were
undertaken in the US and some European countries.
Health and safety issues in the semiconductor man-
ufacturing industry have emerged since 2007 because
of the onset of cancers, including leukemia, in
employees who work in semiconductor manufactur-
ing factories in Korea [9,10].
It is hard to obtain information on the number
and volume of chemicals used in an actual semicon-
ductor factory. Although there are many review
papers and books documenting possible exposure to
chemicals according to the processes used in the
semiconductor industry, this information is generally
considered to be basic and is not based on real data
collected in situ. In terms of safety, health, and envir-
onmental issues, it is important to understand the
actual chemical use in the semiconductor industry.
The objective of this study was to analyze the chemi-
cal characteristics and chemical inventory in a large
CONTACT Chungsik Yoon csyoon@snu.ac.kr Department of Environmental Health Science and Institute of Health and Environment, Graduate
School of Public Health, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, Republic of Korea
The supplement data can be assessed here.
INTERNATIONAL JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HEALTH
https://doi.org/10.1080/10773525.2018.1519957
© 2018 Informa UK Limited, trading as Taylor & Francis Group
semiconductor manufacturing facility in Korea, by
using a database (DB) based on safety data sheets
(SDSs).
Methods
This study was conducted using a chemical informa-
tion DB provided directly by a company that has a
large market share of the worldwide semiconductor
industry. This company has two semiconductor man-
ufacturing factories (called A and B in this study) in
Korea (Supplementary Table 1). The use of chemical
substances is managed independently in each factory.
The DB contains chemical information such as phase,
product number, factory, product name, ingredients,
CAS number, chemical content, processes used, num-
ber of units, and pattern of usage in 2014. The DB
was checked using SDSs provided by the company,
which also kept SDSs provided by each chemical
manufacturer or supplier. Supplementary Table 2
shows part of the DB provided by the company.
The phase refers to the physical status of the products
supplied. Product number is the number assigned to
each product at the company. The product name is
the name of the actual chemical product, which
sometimes contains clues regarding its chemical iden-
tity. For example, the first product name in
Supplementary Table 2 contains information regard-
ing the amount (270 kg or 448 L) of gas supplied per
cylinder, while the second product name contains the
term “photoresist,”which indicates that this chemical
is used in photolithography. From the ingredient and
CAS number column, the number of chemical ingre-
dients and trade secrets per product, and whether a
product contains any hazardous any chemicals, can
be inferred. The amount of each ingredient in a
product is expressed as a relative mass percentage,
with a range of values provided.
The annual amount of chemicals used was calcu-
lated by using information relating to the product unit
(e.g. kg, g, etc.) and statistics on usage per year.
Products were purchased in a variety of units: kg, g,
L, mL, gal, cylinder, bottle, and drum. Every unit was
converted into a mass unit (kg or ton) using available
information. For example, one cylinder of nitrous
oxide has weight of 270 kg, and one bottle used in
Table 1. General overview of chemical products and ingredients used in 2014.
Factory A Factory B
Item
Number of
products
†
Number of
ingredients
with multiple
counting
‡
Number of
ingredients
with a CAS
No.
Average
number of
ingredients
per product
Number of
products
Number of
ingredients
with multiple
counting
Number of
ingredients
with a CAS
No.
Average
number of
ingredients
per product
Total 428 (100%) 1,136 (100%) 189 (100%) 2.7 432 (100%) 1,160 (100%) 157 (100%) 2.7
Phase Gas 182 (43%) 236 (21%) 84 (44%) 1.3 141 (33%) 180 (16%) 69 (44%) 1.3
Liquid 221 (52%) 781 (69%) 96 (51%) 3.5 280 (65%) 931 (80%) 103 (66%) 3.3
Solid 25 (6%) 119 (10%) 18 (10%) 4.8 11 (3%) 49 (4%) 5 (3%) 4.5
Photoresist 92 (21%) 398 (35%) 37 (20%) 4.3 113 (26%) 516 (44%) 32 (20%) 4.6
Carcinogen* 47 (11%) 47 (4%) 5 (3%) 1.0 28 (6%) 28 (2%) 6 (4%) 1.0
†
Among the total number of products, 228 were used in both factory A and B.
‡
All of the chemicals, including those with trade secret ingredients and unknown CAS numbers, were counted, even if the same ingredients were
contained in different products.
*Chemical name [carcinogenicity class, factory]: sulfuric acid (strong acid mist) [1A, A, and B], catechol [2B, A, and B], diborane [2B, A, and B],
naphthalene [2B, A, and B], carbon black [2B, A, and B], and 1,4-dioxane [2B, B].
Table 2. List of chemicals most frequently contained in semiconductor-manufactured products.
Order
Factory A Factory B
Chemical name CAS No.
Number
of pro-
ducts (%)
Number of products
used in photolitho-
graphy (%) Chemical name CAS No.
Number
of pro-
ducts (%)
Number of products
used in photolitho-
graphy (%)
1 Propylene glycol
monomethyl
ether acetate
108–65-6 92 (21.5) 73 (79.3) Propylene glycol
monomethyl
ether acetate
108–65-6 121 (28.0) 90 (79.6)
2 Cyclohexanone 108–94-1 25 (5.8) 23 (25.0) Cyclohexanone 108–94-1 44 (10.2) 38 (33.6)
3 Propylene glycol
Monomethyl
ether
107–98-2 24 (5.6) 13 (14.1) Propylene Glycol
Monomethyl
Ether
107–98-2 35 (8.1) 16 (14.2)
4 Silica, vitreous 60,676–86-0 23 (5.4) Gamma-
Butyrolacton
96–48-0 33 (7.6) 24 (21.2)
5 Carbon black 1333–86-4 21 (4.9) Ethyl lactate 97–64-3 20 (4.6) 19 (16.8)
6 Gamma-
butyrolacton
96–48-0 20 (4.7) 17 (18.5) Hydrofluoric Acid 7664–39-3 14 (3.2)
7 Sulfuric acid 7664–93-9 18 (4.2) 2-Methoxy-1-
propanol
1589–47-5 13 (3.0)
8 Ethyl lactate 97–64-3 16 (3.7) 15 (16.3) Silica, vitreous 60,676–86-0 13 (3.0)
9 Copper(Ⅱ)
sulfate
7758–98-7 15 (3.5) Neon 7440–01-09 13 (3.0)
10 Hydrogen 1333–74-0 12 (2.8) Carbon black 1333–86-4 11 (2.5)
Total 428 (100) 92 (100) Total 432 (100) 113 (100)
2S. KIM ET AL.
the photolithography process is 20 L. If there was no
density information available, we assumed that the
density was 1, so that 1 L was assumed to be 1 kg.
Most of the chemical products for which no density
data were available were photoresist used in the photo-
lithography process: 84 of 428 (20%) and 153 of 432
(35%), products in factories A and B, respectively. Also,
31 of 428 (7%) and 4 of 432 (1%), products in factories
A and B were excluded in the estimation of the annual
amount used due to the lack of information.
In this study, when the amount of a certain ingre-
dient used had to be calculated, the maximum value
of the ingredient over the range of amounts present
in a product was used. Therefore, the amounts calcu-
lated for certain ingredients could have been
overestimations.
Information on health hazards, physicochemical
properties, toxicity, and the Korean occupational
exposure limit (OEL) was added to, or updated in
the DB according to SDSs recently published by the
Korea Government (http://kischem.nier.go.kr)asan
integrated system for managing chemical information
(as part of the Korean Occupational Safety and
Health Act [Korean OSH Act], which was revised in
2015) (http://www.moel.go.kr). Carcinogens were
classified according to the International Agency for
Research on Cancer (IARC) classification and the
Korean OSH Act.
In Supplementary Table 2, trade secret ingredients
are identified in the CAS number column, and are
recorded as being either resins or photosensitive
compounds in the ingredients column. The trade
secret ingredients were classified into six major cate-
gories according to name marked of ingredients col-
umn: additives, photoactive compounds, polymers,
salts and compounds, trade secrets and others. They
were further classified according to their common
name, as shown in Table 5.
Results
Use of chemical products
A general overview of chemical product use in 2014
in factories A and B is provided in Table 1. The
number of chemical products used in the photolitho-
graphy process, which the largest number of chemi-
cals, is presented. The number of chemical products
used in factories A and B was 428 and 432, respec-
tively. Among these, 228 (53%) were used in both
factories. The total number of individual ingredients
in all products was 1,136 and 1,160 in factories A and
B, respectively. These figures include the multiple
counting of chemical products. For example, if a
chemical ingredient was contained in two products,
it was recorded twice. Chemicals with a CAS number
indicating that they were trade secret ingredients, and
those with an unknown CAS number, were excluded.
The total number of individual ingredients in all
products, after multiple counting, was 788 (69%)
and 780 (67%) in factories A and B, respectively.
The number of pure chemical ingredients with a
CAS number, without multiple counting, was 189
and 157 in factories A and B, respectively.
Most chemicals used in semiconductors are sup-
plied in the liquid or gas phase. In factories A and B,
52% and 65% of chemical products were liquids, and
43% and 33% were in the gas phase, respectively.
Only 6% and 3% were used in the solid phase in
factories A and B, respectively, and most of them
were epoxy molding compounds (EMCs), consisting
of silica (CAS No. 60,676–86-0) and carbon black
(CAS No. 1333–86-4). Gaseous chemicals were sup-
plied as a pure gas (e.g. Ar as arsine) or, in a few
cases, as a composite containing the gas (e.g. 4%
phosphine in 96% helium). Liquid or solid chemical
products contained more ingredients: the average
number of chemical ingredients per product was 1.3
for the gas phase in factories A and B, 3.5 or 3.3 for
the liquid phase, and 4.8 or 4.5 for the solid phase in
factories A and B, respectively.
In the photolithography process, 21% (92) and
26% (113) of the chemical products were used in
factories A and B, respectively. Of these products,
37 and 32 chemical ingredients with a CAS number
were included in factories A and B. All of these
chemical products, called photoresists, were present
in the liquid phase, with the number of chemical
ingredients per product being 4.3 and 4.6 in factories
A and B, respectively. The photoresist products have
more ingredients than the liquid products used in the
other processes.
The chemical ingredients classified into groups 1,
2A, or 2B by the IARC, and their associated products,
are presented in Table 1. Ethyl alcohol, classified into
group 1, was excluded because only the drinking of
alcohol was considered to pose a carcinogenic risk.
The number of products with carcinogen ingredients
was 47 (11%) and 28 (6%) in factories A and B,
respectively. The number of ingredients when multi-
ple counting was conducted was identical, which
indicates that there was only one carcinogenic ingre-
dient per product. Without multiple counting, only
five and six ingredients were classified as carcinogens
in factories A and B, respectively: sulfuric acid (CAS
No. 7664–93-9), catechol (12–80-9), diborane
(19,287–45-7), naphthalene (91–20-3), and carbon
black (1333–86-4) in factory A, and the same five
chemicals plus 1,4-dioxane (123–91-1) in factory B.
Sulfuric acid was classified as a group 1 product,
while the others were in group 2B.
The most frequently used chemical ingredients are
listed in Table 2. In both factories, the same three
chemicals were the most common ingredients:
INTERNATIONAL JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HEALTH 3
propylene glycol monomethyl ether acetate (PGMEA;
CAS No. 108–65-6), cyclohexanone (108–94-1), and
propylene glycol monomethyl ether (PGME;
107–98-2). PGMEA was included in 21% (92/428)
of all products in factory A, and in 28% (121/432)
of all products in factory B (with most of the use
being for photolithography; 79% (73/92) in factory A,
and 80% (90/113) in factory B). The average PGMEA
content per product used in photolithography was
72% (range: 15–99%) in factory A and 68% (10–
98%) in factory B. In photolithography, in addition
to PGMEA, cyclohexanone, PGME, gamma-butyro-
lactone, and ethyl lactate were frequently used.
Vitreous silica and carbon black were used in the
EMCs in a packaging plant. The average EMC con-
tent per silica product was 90% (90–93%) in factory A
and 91% (90–95%) in factory B, while for carbon
black products it was 1% in both factories. Most of
the chemical products used in the packaging plant
were EMCs, which contained vitreous silica, carbon
black phenol, and/or epoxy resin or lead (Pb)-free
solder balls, which in turn contained silver (Ag) and
tin (Sn). Some chemicals were used in two or more
processes. Isopropyl alcohol and acetone are the most
popular cleaning solvents in the semiconductor
industry.
The amount of chemicals used on a mass basis is
summarized in Table 3. As described in the Method
section, the mass of 93% and 99% of the products in
factories A and B was estimated. In total, 46,850 and
45,628 ton/year were used in factories A and B,
respectively. Among these, chemicals in the liquid
phase accounted for 95% (44,371 ton) and 97%
(44,284 ton) of the usage in factories A and B, respec-
tively, followed by the gas phase (3% in both fac-
tories), and solid phase (2% and 0.1% in factories A
and B, respectively).
The number of chemical ingredients with a Korean
OEL designation was 44 among 189 (23%), and 46
among 157 (29%), of the chemicals identified as ingre-
dients, i.e. those with a CAS number, in factories A and
B, respectively. In terms of mass, these figures were
47% and 55%, respectively. This means that more than
70% of the chemical ingredients in terms of number,
and about half of them in terms of mass, had no OEL
(including those classified as trade secrets).
Figure 1 shows the amount of chemicals classified as
carcinogens by the IARC in terms of mass. In factory
A, the mass of carcinogenic chemicals was estimated to
be 12,816 tons, although this figure was derived from
only 27 of 47 carcinogenic ingredients (with multiple
counting applied, as shown in Table 1) due to the lack
of information provided. Without multiple counting,
only four chemicals (sulfuric acid, catechol, diborane,
and naphthalene) were used to estimate the amount of
carcinogens. In factory B, mass information was
derived for 27 of 28 carcinogenic chemical ingredients,
with a final estimate of 11,952 tons. 29% in factory A
and 26% in factory B of the total mass of chemicals was
carcinogenic, with sulfuric acid (CAS No. 7664–93-9;
IARC carcinogen group 1) accounting for more than
99.8% of the total (12,804 tons in factory A and 11,930
tons in factory B). In this estimation, the amount of
carbon black used in factory A was not considered due
to the lack of information.
Trade secret ingredients
Table 4 gives the number of products and ingredients
classified as trade secrets according to the overall
contents indicated in the SDSs. There were 186
(43%) and 168 (39%) products classified as trade
secrets in factories A and B, respectively. When ingre-
dients were also included, there were 345 and 363
(about 30%) materials classified as trade secrets in
factories A and B, respectively.
We found that most photoresist products contained
trade secret ingredients. As shown in Table 4,90of92
photoresist products (98%) in factory A, and 110 of 113
photoresist products (97%) in factory B, contained at
least one trade secret ingredient. When also considering
the ingredients, 51% (201 out of 398 materials) in fac-
tory A, and 50% (260 out of 516 materials) in factory B
were classified as trade secrets. The average number of
trade secret ingredients per product was about 0.8 in
factories A (345 out of 428) and B (363 out of 432) for all
products, whereas the average number was 2.2 (92 out
of 201) in factory A and 2.3 (113 out of 260)in factory B
for photoresist products.
Products containing trade secret ingredients were
categorized by content (<1%, 1–30%, 30–60%,
60–80%, >80% trade secret ingredients). The amount
of trade secret ingredients in products was largest in
the ranges of 1 ~ 30% (147 out of 186 and 127 out of
168 products in factories A and B, respectively) and
30 ~ 60% (15 out of 186 and 28 out of 168 products
in factories A and B, respectively). Seven products in
factory A and one product in factory B were com-
posed of more than 80% trade secret ingredients. In
such cases, the product itself was sometimes marked
as a trade secret as shown in Table 4.
Table 3. Amount of chemicals used (by mass and number)
and chemical classification by occupational exposure limit
(OEL) designation.
Factory A Factory B
Number
Amount
(ton) Number
Amount
(ton)
Classification
by phase
Gas 180 1,317 141 1,303
Liquid 216 44,371 277 44,284
Solid 1 1,163 10 40
Total 397 46,850 428 45,628
Classification
by OEL
OEL 44 20,890 46 25,218
Not listed
by OEL
140 23,649 106 20,849
Total 184 44,539 152 46,067
4S. KIM ET AL.
The trade secret ingredients, categorized accord-
ing to their general names, are presented in
Table 5. Several types of polymer were identified
as ingredients in both factory A (145 out of 345
[42%] ingredients) and factory B (158 out of 363
(44%) ingredients). This polymer category was
further divided into nine sub-categories, as shown
in Table 5.
(a) Factory A
(b) Factor
y
B
Figure 1. Number of chemicals classified as carcinogenic by the International Agency for Research on Cancer (IARC) in terms of
mass.
Table 4. The number of products and ingredients classified as trade secrets.
Content comprising trade secret ingredients
Factory A Factory B
Product Ingredient Product Ingredient
Total Photoresist Total Photoresist Total Photoresist Total Photoresist
<1% 4 0 80 11 2 0 76 8
1–30% 147 74 209 172 127 81 241 226
30–60% 15 9 2 5 28 22 4 5
60–80% 6330 1000
>80% 7 0 6 0 1 0 1 0
NI
†
7 4 45 13 9 7 41 21
Overall (%)
‡
186 (43) 90 (98) 345 (30) 201 (51) 168 (39) 110 (97) 363 (31) 260 (50)
†
NI, no information available
‡percentage was calculated as the number of trade secret products or ingredients divided by the total number of products or ingredients
INTERNATIONAL JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HEALTH 5
In the polymer category, resins were the ingredi-
ents most frequently found in both factories, followed
by novolac resin, acrylate polymer, epoxy resin, deri-
vatives, and aromatic polymers. More than half of the
novolac resin, known to consist of phenolic polymer
and/or cresol, used in all processes was used in
photoresist products in both factories. Most of the
epoxy resin used was contained within EMCs applied
in the molding process at the packaging plant. Almost
all of the acrylate polymer, aromatic polymer, and
polymer solids marked as polymers were used in
photoresists; 30 out of 34 in factory A and 39 out of
48 in factory B. Polymers marked as “additives”
accounted for 16% and 13% of all polymers in fac-
tories A and B, respectively. Photoactive compounds
were typical components of photoresist products
within which they were predominantly used. More
than half of all organic salts were used in photoresist
products, but inorganic salts and their compounds
were not used in those products. Materials labeled
as “trade secret,”with no common name given,
accounted for about 5% of the total in both factories.
Other groups of materials included surfactants,
monomers, pigments, compounding chemicals, and
those belonging to the category “other.”
The trade secret ingredient mass values, presented by
category in Table 5, are also presented in Figure 2. There
were 40.4 tons of polymers used in factory A, with 72%
(29.1 tons) used in photoresist products; and there were
54.7 tons of polymers used in factory B, with 68% (37.4
tons) used in photoresist products. All of the photoactive
compounds, 6.7 tons in factory A and 6.5 tons in factory
B, were used in photoresist products. There were 23.1
and 19.0 tons of salts and their compounds used in
factories A and B, respectively, and nearly all of them
were used in non-photolithography processes. About
half of the organic compounds identified were used in
photolithography, as shown in Table 5.
Discussion
We found that more than 150 pure chemical substances
were used in about 430 chemical products in a semicon-
ductor company; about 40% of these chemical products
contained trade secret ingredients. In photolithography,
one of the most widely used processes in semiconductor
manufacturing, nearly all products (about 98%) con-
tained trade secret ingredients, with an average number
of approximately two per product.
The amount of chemicals used was 46,850 and
45,628 tons in factories A and B, respectively, with
the employees in each factory numbering approxi-
mately 110,000 and 5,500, respectively. The chemical
use per person during 1 year was therefore 4.26 tons
in factory A and 8.3 tons in factory B. We did not
determine the exact reason for this difference in che-
mical use per person, but it may be due to the facility
age (factory A was established in 1983, while factory
B was established in 1989 [and had been frequently
renovated]), final products produced (the main pro-
duct in factory A was DRAM compared to NAND in
factory B), or to the final amount of product pro-
duced (these data could not be obtained). It is not
clear if the amount of chemical usage recorded is
large or small compared to other industries, but a
chemical use per person that exceeds 4.6 tons a year
is considerable.
SDSs enable workers to assess the health and safety
conditions in their workplace, but the large amount
of trade secret ingredients used in the semiconductor
Table 5. Classification of trade secret ingredients.
No. Description
Factory A Factory B
Total
†
Photoresist‡Total Photoresist
1Additives 54 (16%) 40 (20%) 49 (13%) 35 (13%)
2Photoactive compound 42 (12%) 39 (19%) 63 (17%) 58 (22%)
3Polymer Resin 40 28 56 36
Novolac resin 24 12 24 18
Epoxy resin 14 1 6 0
Derivative 13 12 11 7
Cross-linker 5 3 5 2
Acrylate polymer 16 13 29 22
Aromatic polymer 10 9 8 7
Polymer solids 8 8 11 10
Other polymer 15 7 8 5
145 (42%) 93 (46%) 158 (44%) 107 (41%)
4Salts and compounds Organic salts and compounds 27 13 29 16
Inorganic salts and compounds 20 0 2 0
47 (14%) 13 (6%) 31 (9%) 16 (6%)
5Trade secrets (No information) 17 (5%) 0 (0%) 15 (4%) 8 (3%)
6Others Compounding chemicals 4 0 4 0
Monomer 0 0 6 6
Surfactant 15 8 12 11
Pigment 0 0 12 12
Others 21 8 13 7
40 (12%) 16 (8%) 47 (13%) 36 (14%)
Total 345 (100%) 201 (100%) 363 (100%) 260 (100%)
†
Number of ingredients (%)
‡Trade secret ingredients classified as photoresist products. The number of ingredients contained in each photoresist (%).
6S. KIM ET AL.
manufacturing industry makes it difficult to obtain
accurate health and safety information. These trade
secret ingredients could easily be omitted during air-
borne chemical monitoring and related risk assess-
ments, even though they may be hazardous.
We found that 40% of all products in both fac-
tories contained at least one trade secret ingredient.
In 2011, a report was published claiming that 45% of
chemical products in Korean chemical manufacturing
plants contained at least one trade secret ingredient
[11]. As shown in Table 4, more than 97% of chemi-
cals used in the photolithography process contained
trade secret ingredients, with the average number of
trade secret ingredients per product being 2.3.
(a) Factory A
(b) Factory B
Figure 2. Amounts of trade secret ingredients in terms of mass by material category. (a) Factory A (b) Factory B.
INTERNATIONAL JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HEALTH 7
The trade secret ingredients shown in Table 5 were
classified according to their corresponding SDSs, but
some trade secret ingredients could have been
included in other categories. The chemicals used in
the photolithography process are classified as photo-
active compounds, polymers, solvents, or additives
[12,13]. Almost all of the trade secrets ingredients
were photoactive compounds and polymers.
Photoactive compounds that react with light generate
an acid, and then the dissolution properties of the
polymer are changed. For example, many polymers
are used as photoactive compounds, but are classified
only by their name. Six monomers identified in fac-
tory B must in fact be units of a polymer, because
monomers are not usually used in the semiconductor
industry. However, we classified them as monomers
according to the information provided on the SDSs.
Certain trade secret ingredients listed as “additive”
and “trade secrets”in Table 5 could belong to the
photoactive compound or polymer groups, because
they were used in the photolithography process.
An understanding of the semiconductor manufac-
turing process is necessary to evaluate the chemical use
in the industry. For example, as technology has devel-
oped, the width of the patterning line on the wafer
surface has decreased and the chemicals used have
changed accordingly. In the past, novolac resin was
usually used as a polymer during application of spec-
tral lines at 436 nm (“g-line”) and 365 nm (“i-line”).
However, as shorter wavelengths have been developed,
polyhydroxystyrene (PHS) polymer and acrylate poly-
mer have been used instead of novolac resin to pro-
duce KrF (248 nm) and ArF (193 nm) light sources,
respectively [12,14–16]. In the company investigated
here, many light sources were used and therefore
many polymers were also employed.
More than 97% of the products used in the photo-
lithography process in both factories included trade
secret ingredients. Therefore, it was difficult to deter-
mine the exact characteristics of the products using
the SDSs of products provided by the chemicals
manufacturer.
According to the Korea OSH Act, in Korea, carci-
nogens, mutagens, and reproductive toxins (CMRs)
should be listed in SDSs if their contents are above a
defined limit (≥0.1% for carcinogens and mutagens
and ≥0.3% for reproductive toxins). In this study, we
could not confirm the existence of CMRs or other
health hazards within trade secret ingredients due to
the secrecy involved, although more than 340 ingre-
dients were categorized as trade secret ingredients, as
shown in Table 5. We are now conducting a further
study to analyze photoresist products and determine
which are CMRs.
The photolithography process uses many chemical
products, which in turn contain many organic sol-
vents and polymers. These solvents, and the by-
products of polymers, could be emitted during coat-
ing, as well as the soft bake and hard bake stages.
After photoresist coating in photolithography, a
wafer-coated photoresist is baked at 70–90°C in the
soft bake stage, and at 120–135°C in the hard bake
stage [8].
It is known that certain unused chemicals, includ-
ing benzene, toluene, cresol, and other chemicals, are
generated during the pyrolysis of photoresist pro-
ducts containing novolac resin [17]; more sensitive
workers might feel uncomfortable about the atten-
dant risk of adverse health effects [18].
During the packaging process, EMCs are represen-
tative compounds used in molding. On average, four
ingredients were identified in EMCs in this study,
including carbon black and silica (84% of all products
in factory A and all products in factory B), as well as
trade secret ingredients such as phenolic and epoxy
resins. Although almost all of the EMCs were com-
posed of silica (average 90%) and carbon black (aver-
age 1%), epoxy and/or phenolic resins were also
present in EMCs and photoresist products. It was
reported previously that benzene (an IARC group 1
carcinogen), phenol, and formaldehyde (an IARC
group 1 carcinogen) were generated as byproducts
of EMCs during the molding process, although their
concentrations were low [17,19]. Pb was used as a
solder ball ingredient in the past, but is no longer
used because it is subject to the European Union
(EU) legislation on the restriction of hazardous sub-
stances (RoHS) [20].
Although the proportion of products that included
carcinogens, as classified by the IARC, was only about
10% of the total number of products used in both
factories, we found that the proportion of carcinogenic
ingredients was about 30% of the total amount of
ingredients used. Sulfuric acid, an IARC group 1 car-
cinogen, accounted for more than 99% of the total
amount of carcinogenic chemicals. Many studies
have reported that sulfuric acid is used in a variety of
semiconductor manufacturing processes, including
cleaning, wet etching, and wet stripping, all of which
are subsumed by the fabrication process [3,13,21].
According to the “Survey on the distribution and use
of chemicals; sulfuric acid”published by the Korea
Occupational Safety and Health Agency (KOSHA) in
2009, sulfuric acid with a 98% concentration has been
used as a wafer etchant in the semiconductor manu-
facturing industry [22]. This was also apparent from
the information provided on the SDS referred to in
this study. In Korea, the airborne concentration of
sulfuric acid in semiconductor manufacturing facil-
ities is reported to be low or non-detectable [23].
In the company investigated here, there was no DB
or management system that could be consulted to
determine how many chemical products were used
in each process, and in what amounts.
8S. KIM ET AL.
It was difficult to classify chemical products by process
because the Safety, Health, and Environment (SHE) team
in the company had no DB available that we could
consult. The process of semiconductor chip manufactur-
ing is usually divided into fabrication and packaging
stages [8,24]. We could only use promotional materials
provided by the company in our investigation. The fab-
rication process has been categorized into various photo-
lithography stages, as follows: etching; thin film (T/F)
production, including chemical vapor deposition (CVD)
and physical vapor deposition (PVD); diffusion, includ-
ing implanting and furnace heating (oxidation, anneal-
ing); and C&C including chemical mechanical polishing
(CMP) and cleaning. In another process, metal copper
was used to make a chip in both factory A and factory B.
The packaging stage consists of back grinding, wafer
sawing, die attachment, wire bonding, molding, marking,
solder ball mounting, a saw singulation test –which
includes a test during burn in (TDBI) –and packing.
During fabrication, chemicals are used in every step,
especially in the photolithography process. In packaging,
most chemicals are used in the molding, solder ball
mounting, and marking processes. Some chemicals are
used in several processes, with cleaning solvents like
isopropanol and acetone used both in the fabrication
and packaging stages.
The Korean government frequently inspects the
semiconductor company involved in this study.
After the most recent survey, the company imple-
mented a human resource management system and
integrated it with a “job exposure matrix (JEM)”in
which every worker’s job history, chemical use, and
qualitative exposure were recorded.
It is not easy to manage levels of exposure to chemi-
cals in the absence of guidelines or standards. In the
workplace, OELs frequently used as a guideline or legal
standard. As shown in Table 3, a very small proportion
(24% [44/184] and 30% (46/152]) of the chemicals used
in factories A and B, respectively, have OELs. The other
chemicals used are not monitored or regulated. It should
be noted that the chemicals used in the semiconductor
industry have different characteristics compared to the
chemicals used in other manufacturing industries. For
example, they were introduced relatively recently, they
are atypical compared to the chemicals used in other
manufacturing industries, there is a high level of secrecy
regarding their composition, and there has been a rapid
change in the use of these chemicals following recent
technological developments [5,10]. This makes it difficult
to control chemical hazards in the semiconductor
industry.
Trade secrets are difficult in terms of work environ-
ment management, although they are necessary for com-
panies. Because we do not know the harmfulness of the
substance without knowing the ingredient. Moreover, as
shown in Table 4, many chemical products contain trade
secretsandthecontentsoftradesecretsarehighinmany
cases. In the SDS, trade secrets are limited to the compo-
nent name and content. It is important that all other
information, including health and safety information, is
recorded so that it is known to the user. If the name of the
ingredient is not known, it can not be verified that the
remaining information is correct. If the content of the
trade secret substance is high, it means that the amount
of the ingredient is unknown, which means that the risk
increases. The SDS should contain the trade secret ingre-
dient only if it is absolutely necessary, but if not inter-
ested in the government or the down streamer, the
chemical manufacturer may set a lot of trade secrets
intentionally and/or unintentionally. In Korea, prelimin-
ary trade secrets review system will be introduced to the
Industrial Safety and Health Act in order to supplement
these shortcomings.
This study had some limitations. First, it was difficult
to estimate the exact amount of ingredients used because
the content of each ingredient was provided as a range in
theSDSs.Weusedthemaximumvalueoftherange
reported in the SDSs when estimating the amount of
each ingredient, but this did not affect the amount of
product originally produced this company. Second, the
photoresist chemicals classified by the process could not
be estimated exactly, as explained in the Discussion sec-
tion. Third, this study was conducted by consulting only
a chemical DB and SDS. If there were any disparities
between the information contained within these docu-
ments and their actual use in the workplace, there could
be errors in the analysis. For example, factory A con-
tained a research institute, in which many chemicals
were used and removed on a temporary basis, but we
could not locate it within the facility.
Conclusions
This study evaluated chemical use in two factories
operated by one of the largest semiconductor manufac-
turing companies in the world. More than 420 chemical
products (428 in factory A and 432 in factory B), which
contained more than 150 pure chemical ingredients
(189 in factory A and 157 in factory B) were used,
with 40% of them containing trade secret ingredients.
More than 97% of the chemical products used in the
photolithography process, one of the most widely
applied chemical processes, contained trade secret
ingredients. Less than 30% of the chemical ingredients
had OELs. Because of the high percentage of trade
secret ingredients, limited number of regulated chemi-
cals, and atypical chemical use compared to other
industries, it is difficult to assess health hazards in the
semiconductor industry. In 2014, more than 45,000
tons of chemicals were used in each factory and sulfuric
acid, classified as a group 1 carcinogen by the IARC,
accounted for about 30% of the total amount.
It is important to establish and implement a che-
mical management program in-house.
INTERNATIONAL JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HEALTH 9
The company will filter out chemical components
that should not be entered at the time of purchase of
chemical products and establish a system to review SDS
and other safety and health information to comply with
laws and regulations. The company should share chemi-
cals management policies with chemical suppliers and
make efforts to reduce the number of possible trade
secret substances. Periodically update the SDS of incom-
ing chemicals with the latest information and practice
the right of workers to know. It shall periodically receive
acertificate that the trade secret substance does not
contain substances prohibited by law, including CMR.
Acknowledgments
This work was supported by BrainKorea21 (BK21) Plus
project of the National Research Foundation (NRF)
[Grant number 2580-20180100].
Disclosure statement
All authors have no conflicts of interest to declare.
Funding
This work was supported by the BrainKorea21 (BK21) Plus
Project of the National Research Foundation (NRF) [Grant
number 5280-20180100].
ORCID
Seunghon Ham http://orcid.org/0000-0002-5167-9661
Jihoon Park http://orcid.org/0000-0002-4829-5587
Ohun Kwon http://orcid.org/0000-0001-5609-4788
Sangjun Choi http://orcid.org/0000-0001-8787-7216
Won Kim http://orcid.org/0000-0003-1808-6677
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