The Greening of the Semiconductor Industry

As part of a new focus on sustainability, the semiconductor industry is building new fabs (and labs) designed for LEED certification. There's also a push to reduce energy and water consumption while minimizing hazardous waste and emissions.

Peter Singer, Editor-in-Chief -- Semiconductor International, 12/1/2007

A semiconductor manufacturing fab can consume as much electricity in a year as 10,000 homes (170,000 MW) and up to 3 million gallons of water per day. Annual utility bills can be as high as $20M–$25M.

Those are just some of the reasons why new semiconductor manufacturing fabs are going "green" by becoming more environmentally friendly. New approaches not only reduce electricity and water use, but also aim to reduce global warming emissions, volatile organic compounds (VOCs) and hazardous materials. Designers are turning to natural skylights, solar energy, retention ponds, reflective roofing and concrete to reduce costs. Energy savings are also found through the use of smart, networked lighting and by optimizing how equipment is run — putting vacuum pumps into "sleep mode" when not in use, for example. Fabs are also finding new ways to recycle water and chemicals and reduce the amount of hazardous waste.

Reducing cost is not the only reason for the new green push. It's also part of a movement known as sustainability, which embraces aspects of economic, environmental and social developments as part of the corporate culture. A sustainable system delivers services without exhausting resources, and uses all resources efficiently both in an environmental and economic sense.

1. Texas Instruments's Richardson, Texas, fab was designed from the beginning to be LEED-certified.

The ultimate in "green" building design is now defined by the Leadership in Energy and Environmental Design (LEED) rating system, developed by the U.S. Green Building Council. The system promotes a "whole building" approach to sustainability by recognizing performance in five key areas of human and environmental health: sustainable site development, water savings, energy efficiency, materials selection and indoor environmental quality. It can be applied to new construction and existing buildings.

Although not yet operational, Texas Instruments's (TI) fab in Richardson, Texas, was designed to be the world's first "green," LEED-certified semiconductor manufacturing facility (Fig. 1). Designed for 45 nm production on 300 mm wafers, the building is 1.1 million ft² of space on 92 acres of land, and includes administration, mechanical, support and fabrication buildings (Fig. 2).

TI said the building was designed with particular attention given to minimizing the environmental impact. TI engineers spent time with experts from the Rocky Mountain Institute to create an extremely efficient complex unlike any other TI semiconductor facility. Some more notable elements include:

• An on-site retention pond to collect rain that decreases storm run-off and can be used for irrigation

• Native prairie grassland and vegetation that require little to no water or maintenance to thrive

• Reflective roofing and concrete to reduce urban heat island effect

• Waterless urinals, saving ~40,000 gallons/year/unit

• Faucets with sensors that are recharged by a small water turbine

• Light shelves to utilize natural daylight instead of fluorescents inside office areas

• Windmill-powered pond aerator

• Light and motion sensors

• Demand-controlled ventilation

• Solar water heater for administrative areas

• During construction, TI recycled more than 90% of the waste and made extensive use of recycled materials in the building's structure and decor.

Although building "green" required some additional investment to realize long-term operating benefits, it added up to &1% of the construction budget. In addition, the plant was successfully built for an estimated 30% less in cost than a similar TI manufacturing plant constructed just six miles away only a few years earlier. This latter achievement increased the building's cost competitiveness among other semiconductor manufacturing facilities being built outside of the United States, according to the company.

2. Although not yet operational, Texas Instruments’s new fab occupies 1.1 million ft2 space on 92 acres of land, and includes administration, mechanical, support and fabrication buildings.

Speaking at the recent International Trade Partners Conference (ITPC), Shaunna Black, TI vice president, said in the first full year, the company should save $1M in operating costs and, at full build-out, more than $4M/year with 20% energy reduction, 35% water-use reduction and 50% emissions reduction.

Another new fab aiming for LEED certification is Intel's Fab 32, its new 45 nm fab in Chandler, Ariz. (Fig. 3). It's described as one the company's "most environmentally friendly" factories, incorporating a number of energy and water conservation measures. Intel said new processes result in a 15% reduction in global warming emissions, and that it makes use of Arizona's water conservation and reuse program, which conserves more than 70% of the water. The company said that it intends to seek certification for the new fab as the company's first official LEED factory.

3. Intel's new 45 nm fab in Chandler, Ariz., is one the company's most environmentally friendly fabs. Intel said it intends to seek certification as the company's first official LEED factory.

One building, possibly the first microchip fabrication facility to receive LEED certification, is Sandia Corp.'s newly completed three-story MESA Microsystems Fabrication (MicroFab) facility. Energy efficiency is an integral part of the MESA project design, including a highly efficient central utility building that serves both the MicroFab (Fig. 4) and the adjacent MicroLab buildings. The MicroFab incorporates a high-efficiency ultrapure water (UPW) generation process, water recycling loop, and the reclaim and reuse of water for cooling and scrubber applications.

4. Sandia's newly completed three-story MESA Microsystems Fabrication (MicroFab) facility has already received LEED certification, an industry first.

Other project-specific "green" measures include accessibility to alternative transportation options, occupant-based water-efficient plumbing fixtures, and a low water use landscape design. Resource conservation through waste management, as well as the incorporation of recycled and locally manufactured materials, were also emphasized in the project.

R&D facilities are also turning "green." The Molecular Foundry (Fig. 5), a nanotechnology research facility located at the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley, Calif.), received LEED Gold certification. The Molecular Foundry's Gold rating — the second-highest ranking obtainable under the system — is based on the use of a myriad of features, including optimally designed electrical and HVAC systems, an energy-efficient chiller and boiler plant, and the innovative design of traditionally energy-intensive areas such as labs, a cleanroom and a server room. Because of these and other measures, the Molecular Foundry consumes 28% less energy than the already-stringent California building efficiency standard. The Molecular Foundry also consumes 35% less energy than the national energy standard and produces 85% less greenhouse gas emissions than a conventional facility.

5. The Molecular Foundry, a nanotechnology research facility located at the U.S. Department of Energy's Lawrence Berkeley National Laboratory, received LEED Gold certification.

"LEED classification is a holistic look at the sustainability of a building, and is much more than energy efficiency," said Joe Harkins, project manager of the Molecular Foundry. "While the Foundry is one of the most energy efficient buildings ever constructed at Berkeley Lab, it also provides an exceptional work environment. Extensive use of daylighting, operable windows, protection of indoor air quality through low-VOC materials and clean-construction practices, all contribute to a great work environment."

Green process, tool changes

Beyond building "green," semiconductor manufacturers are looking at what they can do to be more environmentally friendly on a day-to-day basis. At the ISMI International Symposium on Manufacturing Effectiveness held in October, several companies presented ways to reduce CO₂ emissions and hazardous waste.

Andes Chan of Applied Materials (Santa Clara, Calif.) noted that companies are becoming more cognizant of their carbon footprint. "Countless legislation both in existence and planned require that companies account for and implement solutions to reduce emissions such as carbon and other toxic gases. Whether it is the California Global Warming Solutions Act, the New Jersey Global Warming Response Act, or World Semiconductor Council PFC reduction commitment, companies are challenged to find strategies for reducing emissions," he said.

The largest component of energy consumption is typically caused by facility and semiconductor equipment use. Depending on a factory's production level, gases and other direct emissions from wafer processing can be significant sources of carbon footprint. Resource conservation and CO₂ emissions reduction, either direct or indirect, require reviewing a broad range of technology and then applying optimal solutions that are best-suited for a company's processes and facilities, Chan said.

Applied Materials's strategies to reduce perfluorocarbons (PFC) emissions include optimizing process efficiency through improved etch recipes, and remote plasma cleans for chemical vapor deposition (CVD), for example, substituting chemistry if possible, such as C₄F₆ for selected etch applications, and finally abatement technology to convert or destroy PFCs.

At Samsung Electronics Co. (Seoul, Korea), PFCs have been reduced by switching CVD chamber gases, such as CF₄, C₂F₆ and C₃F₈, to alternatives such as NF₃. The company also made equipment changes, including a switch from in situ to remote plasma cleans.

Wastes to riches

One of the best success stories — several stories actually — in turning "green" came from Spansion (Sunnyvale, Calif.). Presenting at ISMI, Mike Frisch and Marcel Montalvo said starting in 2006, Spansion transformed its management of waste streams with the following goals in mind: improving environmental performance by seeking reuse or recycling instead of waste treatment — decreasing the quantity of hazardous waste generated — and reducing costs.

Environmental performance is ultimately measured by the amount of pollution created as a result of an activity (e.g., manufacturing flash memory). Frisch noted that less pollution will be created if a waste stream is recycled vs. treated, reused vs. recycled, reduced vs. reused, and ultimately not generated if replaced with a process that does not generate a waste or byproduct stream. The primary focus of the Spansion effort was to reuse and recycle, rather than treat, waste streams.

Case study 1 — Spansion's Fab 25 (Austin, Texas) generates ~2.9 million pounds of spent sulfuric acid per year. This material is 80% sulfuric acid and has very low levels of metal and organic impurities. Prior to this effort, the acid was being transported to a sulfuric acid reprocessing facility that recycled the acid back into the raw materials used to make virgin sulfuric acid. Spansion split the $1140/trip transportation charge with the recycler. A galvanizing company was identified as an ideal candidate to reuse the spent acid as a feedstock to replace virgin sulfuric acid; however, a deal could not be reached because the galvanizer did not want to assume the transportation liability. The company contacted a product management company to identify a facility that could both reuse the acid and handle the associated transportation liability. The company found a ferrous sulfate production facility within 100 miles of Austin that would reuse the entire stream. Spansion not only saved $42,000/year on transportation costs, but is now paid $10/ton for the acid. Additionally, Spansion is no longer required to obtain certified analyses for iron and assay, eliminating $400/shipment in laboratory costs. Combined savings, revenue and cost avoidance for this project was $85,000/year. Spansion's environmental performance improved as a result of the reduced transportation mileage to the end-use facility, the elimination of energy used and pollution generated by both the sulfuric acid reprocessing and manufacturing processes, and the elimination of virgin sulfuric acid transportation.

Case study 2 — Spansion's Fab 25 generates ~207,000 lbs of 75% isopropyl alcohol (IPA) in its wafer drying process. Prior to this effort, the IPA was commingled with other solvent waste, collected and transported off-site as a hazardous waste to be burned as a fuel at a chemical manufacturing facility in Houston. Spansion worked with another product management company to segregate, repackage and reuse the IPA stream as an industrial cleaner. As a result of the project, Spansion saved ~$12,000/year in waste disposal costs, and an estimated revenue of $15,000/year is generated from the actual sale of the IPA. Additionally, the company will no longer have to report more than 200,000 lbs of material per year as hazardous waste. Spansion improved its environmental performance by eliminating both energy use and pollution generated by the transportation to the waste treatment facility, waste treatment process, and the manufacturing of virgin material.

Fab 25 generates ~5000 lbs of used oil each year from the maintenance of motorized equipment. Prior to this effort, the used oil was commingled with solvent waste and transported off-site as a hazardous waste. A regional oil recycler agreed to collect the used oil at no charge, saving Spansion $250/year in waste treatment costs and removing 5000 lbs/year from hazardous waste reporting.

Case study 3 — Spansion's Fab 25 began generating ~82,000 lbs/year of spent copper sulfate bath in 2006 as a result of high-volume manufacturing of its new copper flash technologies. The copper sulfate- and sulfuric acid-rich stream was being hauled off as a hazardous waste to a wastewater treatment facility. This particular method of wastewater treatment generates a copper sludge that is disposed of in a hazardous waste landfill. Spansion identified a metals recycling facility that uses a multi-step process to remove valuable metals, including copper, from the streams. The sulfuric acid content of the copper sulfate stream is actually used to digest other incoming streams, so the spent bath replaces virgin sulfuric acid that would otherwise be purchased by the facility, and is no longer characterized or reported as a hazardous waste.

The cost savings details for the projects completed to date are shown in the Table. Through reuse and recycling instead of waste treatment, Spansion has reduced liquid waste costs by 92% and reduced hazardous waste by 294,000 lbs/year while achieving great strides in environmental performance. Continuing efforts at the company have revealed additional opportunities — phosphoric acid and edge bead remover reuse — that could save Spansion as much as $150,000/year and eliminate up to 500,000 lbs of hazardous waste generated per year.