toward Green Manufacturing
Should Be Met during Process R&D Stage
Moslehi, PhD, is chief technology officer and senior vice president,
semiconductor technology research, for The Noblemen Group, a boutique
investment banking, strategic advisory, and business development firm.
Moslehi has 20 years' experience working in the semiconductor and semiconductor
equipment industries. He can be reached at email@example.com.
its critical importance, the semiconductor industry has been somewhat
conservative in implementing large-scale environmental initiatives, mainly
because of the complexity of the manufacturing processes. With a few exceptions,
the industry has not treated this issue as seriously as other technical
industry traditionally has accepted change, as long as it is cost effective
and does not present the slightest risk in the fab or to the product,
alter processes of record, or require requalification. However, the introduction
of several major environmental protection regulations and protocols has
triggered a more accelerated adoption of "green manufacturing" practices
in the semiconductor industry.
a global economy, any environmental regulation, such as the two far-reaching
directives enacted by the European Union (EU), fully affects all semiconductor
manufacturers that market and sell their products worldwide. These two
EU directives are known as Waste from Electrical and Electronic Equipment
(WEEE) and Restrictions on the Use of Hazardous Substances (RoHS).
is considered a major source of heavy metals and organic pollutants. The
WEEE directive is designed to prevent waste and improve disposal requirements
through promotion of prevention, reuse, recycling, and recovery techniques.
When it takes effect in August, the directive will hold manufacturers
and suppliers of 10 categories of equipment—including electrical and
electronic equipment—responsible for collection, recycling, and end-of-life
disposal of their products.
RoHS directive addresses health issues and is intended to reduce leaching
of hazardous substances out of landfills into ground and surface waters,
and to lower the emission of incinerated toxic chemicals into the air.
Starting in July 2006, the directive will ban lead, mercury, cadmium,
hexavalent chromium, and the polybrominated biphenyl flame retardants
PBB and PBDE.
Japan, the "Pollutant Release and Transfer Register" (PRTR) laws control
and report the extent of certain chemicals and substances released into
the environment and promote the improved management of them. The U.S.
Environmental Protection Agency has lowered the maximum allowable lead
threshold in products. China is adopting pollution control measures for
electronic products that are similar to the EU RoHS directives. The Montreal
Protocol restricts chlorofluorocarbons and other ozone-depleting chemicals,
while the Kyoto Protocol aims at reducing greenhouse gas emissions (including
carbon dioxide) that lead to global warming. Perfluorinated compounds
(PFCs), which are used in semiconductor process equipment chamber cleaning
and etch processes, are very stable greenhouse gases. The World Semiconductor
Council has set goals for reduced PFC emissions by 2010.
response to RoHS, a major worldwide effort has been under way to eliminate
lead entirely from the packaging and assembly manufacturing processes.
Following years of effort, lead-free solder pastes (such as silver-tin-oxide)
have been developed and introduced. Many issues have been resolved, such
as whisker growth and challenge of a narrower process window caused by
the higher melting point and different thermal and reflow profile. Green
products, in addition to meeting RoHS requirements, are free of chlorine,
bromine, and antimony, and do not use any red phosphorus.
14001, the International Standards Organization (ISO) environmental standards
series, addresses the environmental management of businesses and green
manufacturing practices. The standards provide guidelines and controls
for energy consumption, waste handling and treatment, and other activities
that affect natural resources and the environment. ISO 14001 evaluates
the environmental impact of a company and its products. It is designed
to help set targets to meet requirements, develop and prioritize environmental
response plans, document environmental policy and procedures, implement
ongoing measurements against targets, and provide guidelines for internal
green manufacturing goes well beyond ISO 14001. The life cycle assessment
(LCA) technique quantitatively analyzes and assesses the environmental
impact of a product throughout its life, starting from the raw material
stage, continuing through manufacturing, all the way through its transport,
usage, and disposal. A useful tool, LCA supports the manufacturing of
green products with minimum amounts of atmospheric emissions, aqueous
effluents, and solid wastes. By reducing air, water, and land pollution
and improving air and water quality, this leads to improved health and
safety through better protection of the ecosystem.
friendly products also reduce energy consumption levels, use recyclable
components, and offer proper disposal procedures. During product manufacturing,
the elimination, reduction, recycling, and reuse of chemicals and water,
combined with proper waste control and treatment of those chemicals, should
be major areas of focus. Conservation practices would further reduce the
usage of energy, electric power, water, and paper.
example from the semiconductor industry is the critical environmental
and toxicological challenge of wafer- cleaning chemicals and solvents.
Environmentally friendly manufacturing considerations have generated strong
interest, including reduced chemical and water usage, development of more-benign
chemistries and, where possible, elimination of liquid solvents and chemicals.
In wet wafer-cleaning tools, chemical usage can be reduced through the
use of dilute chemistries, increased bath lives, decreased operating temperatures,
reprocessing, the use of bath lids and covers, and the adoption of small,
single-tank systems. Improvements in vapor-phase Marangoni drying have
led to huge reductions in isopropyl alcohol consumption.
major improvements over the years, the reduction of pure water usage has
been more difficult. More recently however, the use of ozonated DI water
and small, single-tank systems have helped reduce water consumption. By
replacing sulfuric acid/hydrogen peroxide mixture (or piranha solution)
with ozonated DI water, as well as replacing the popular RCA cleans (SC-1
and SC-2) and HF solutions with highly dilute chemistries, a typical high-volume
production fab would cut its annual chemical expenditures by millions
of dollars. An additional benefit of these actions would be improved yields.
use of wafer-cleaning solvents presents many challenges to materials suppliers
and their customers. For example, the EU has banned the replacement for
hydroxylamine-based chemistries, which are used in back-end-of-line resist
strip. These solutions have been developed in recent years at great expense,
and potential stripping alternatives may not be as effective. This case
shows that a broader perspective and approach is needed, one that leads
to more-successful technical and financial results across the entire supply
chain while also meeting the intended environmental targets throughout
a product's life cycle.
formulas must be found for establishing effective communication forums
among customers, manufacturers, suppliers, and regulators, beginning in
the early phases of research and product development and continuing throughout
a product's implementation. It would also be more economical to follow
a uniform set of global standards. Improved communication combined with
better standardization would help contain and reduce costs, which would
otherwise be passed on to the end-users.
many cases, environmentally benign manufacturing techniques and practices
are economically beneficial, provided that the concepts of design for
environment (DFE) are strictly followed. Potential risks must be addressed
and implementation costs minimized. Therefore, it is critical to evaluate
and introduce DFE methods correctly and in a timely fashion, right from
the onset of the research and process and product development phases.
The entire sequence of each process module, as well as the interactions
among the various process steps, must be fully optimized for the environment.
In addition, green manufacturing concepts must be followed throughout
the entire supply chain.
National Science Foundation/ Semiconductor Research Corp. (NSF/ SRC) Engineering
Research Center for Environmentally Benign Semiconductor Manufacturing
(led by the University of Arizona in Tucson) has emerged as a major research
contributor to these green chipmaking efforts. The center's stated objectives
include "creating new and effective environmentally benign manufacturing
processes" and "demonstrating the positive impact of design for environment
on all aspects of semiconductor manufacturing."
the semiconductor industry has been very slow in reacting to change, including
the implementation of environmental initiatives. However, experience has
shown that environmental benefits and economic gains are not mutually
exclusive. Cost savings can be achieved through reduced energy consumption,
improved health and safety, better efficiency and productivity, waste
minimization, and more-effective waste treatment and disposal. Even insurance
premiums may be lowered because of better compliance with safety regulations.
Companies that recognize these facts can enjoy an enhanced image as a
socially responsible corporation and a competitive edge in marketing,
as well as many other potential economic benefits.
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