SESHA 2011 Program Book - Semiconductor Safety Association

ticles (NPs). Numerous reports have been published in
recent years expressing concern for the potential toxicity
of NPs to humans and ecologically important species.
The objective of this work was to investigate the
potential cytotoxicity of nanoscale inorganic oxides
commonly utilized in semiconductor manufacturing
(SiO2, Al2O3, CeO2) and emerging inorganic oxide
nanoparticles (HfO2). Other commercially-important
inorganic oxides (ZnO, TiO2, ZrO2, Mn2O3) were also
included in the study for comparison. Nanotoxicity was
assessed using several well-established bioassays (e.g.,
Microtox, yeast respiration measurements, MTT) and
a recently developed impedance-based Real Time Cell
Assay (RTCA). The target cells in those bioassays included
bacteria, yeast, and human cells. Additional assays
were performed to evaluate the potential involvement
of reactive oxygen species (ROS), toxic soluble
species, and/or decrease in cell membrane integrity on
cytotoxicity. Furthermote, the particle size distribution
and fraction of inorganic oxide effectively dispersed in
the various bioassay media was investigated in order to
get information on the actual hydrodynamic diameter
and state of dispersion of the nanomaterials. With the
exception of SiO2 which formed highly stable dispersions,
the nanoscale inorganic oxides tested showed a
high tendency to aggregate in most biological media resulting
in micron-size aggregates that settled out of the
dispersion. ZnO and Mn2O3 were the most inhibitory
inorganic oxide nanomaterials evaluated with 50% inhibiting
concentrations often in the low ppm range. In
contrast, CeO2 and HfO2 were nontoxic in most assays
at concentrations as high as 1,000 mg L-1. Nanosized
SiO2 and Al2O3 showed intermediate to low cytotoxicity.
The underlying mechanisms involved in the cytotoxicity
of these nanomaterials are currently under investigation.
Furthermore, the results obtained indicated the
potential of impedance based RTCA to rapidly screen
for nanoparticle toxicity. Future research will address
validation of the RTCA results using conventional cytotoxicity
tests.
8
2:30 pm Preventing Musculoskeletal Discomforts
for a Healthy Workplace
Lin, R-T; Taiwan Semiconductor Manufacturing Company,
Taiwan
Musculoskeletal diseases are on top, accounting
for 73%, of the ranking of compensated occupational
diseases in 2010 in Taiwan. Previously reported musculoskeletal
discomforts among fabrication room (fab)
workers were owing to frequent manual wafer pod handling
or operating manufacturing equipments with improper
anthropometric data for users in different countries.
In addition, sufferers of work-related tendinitis are
entitled to compensation since 2010 under the new list
of occupational diseases in Taiwan, leading to an anticipated
soar of work-related musculoskeletal diseases
compensation due to long hours of use or repetitive typing
among computer users. Providing an ergonomic
working interface for a company with hundreds of thousands
workers is a challenge to balance the purchase
specification and cost. Under the changing working
interface from on-site process equipment operation to
remote computer monitoring, the report aims to provide
an overview of prevalent trends, regulatory standards,
and challenges of musculoskeletal disease among different
countries. The report demonstrates our systematic
approach for reducing workers’ awkward postures and
musculoskeletal complaints through ergonomically redesigned
fab/office workstations. In addition to statistical
data, the report also includes an introduction of health
care programs on solving musculoskeletal discomforts,
such as massage and traditional Chinese medicine lectures.
Information on the effectiveness of ergonomic
programs has been computerized and integrated into e-
ESH system. Our case studies and experience sharing
may be of use in both policy and practice for reducing
ergonomics-related occupational diseases and promoting
a healthier workplace.
3:15 pm Break & Raffle Distribution, Exhibit Hall
3:45 pm Tetramethylammonium Hydroxide
(TMAH): Toxicity and Methods to Reduce Risk in
the Workplace
DiZio, K, Melville, R, Timlin, E; IBM, San Ramon, CA
and Hopewell Junction, NY
Tetramethylammonium hydroxide (TMAH), CAS
#75-59-2, is employed in an increasing number of semiconductor
manufacturing processes. Newer applications
may use TMAH concentrations as high as 25% at elevated
temperatures. Contact with concentrated TMAH
solutions may cause serious intoxication. Several fatalities
have been reported by the Asia Pacific semiconductor
and photoelectric industries. Factors that may
be important in determining the degree of intoxication
include the concentration of TMAH, the % body surface
area affected, the period before decontamination, and
the possibility of concurrent inhalation exposure and
dermal contact. Early toxicity studies in rats and guinea
pigs identified TMAH as highly toxic with an oral LD50
in rats between 34 and 50 mg/kg and a dermal LD50
in guinea pigs of 25 to 50 mg/kg. Later studies in rats