Issue



Addressing ESH issues for the global semiconductor industry


07/01/2009







Ron Remke, Tom Huang, Steve Trammell, Laurie Beu, Walter Worth, ISMI, Austin, Texas USA

The semiconductor industry prides itself on being proactive in environment, safety, and health (ESH) and has achieved an impressive record in pollution prevention, worker protection, and manufacturing risk management. However, with the advent of globalization, the squeeze on profit margins as the industry matures, and the drive toward greater productivity, leveraging available ESH funds and avoiding duplication of research and development efforts have become increasingly more important. In response, ISMI created the ESH Technology Center, a collaborative enterprise of semiconductor manufacturers and equipment and material suppliers globally.

To address the energy and resource conservation needs of the semiconductor industry, ISMI launched its ESH Technology Center in 2009. The center is dedicated to semiconductor manufacturing sustainability via green technologies that reduce energy consumption, lower costs, and promote greater productivity in manufacturing. Areas targeted include fab and facilities energy and resource conservation; climate change and environmental impact; supply chain ESH alignment; chemical management;ESH impacts of semiconductor materials, equipment, and processes; manufacturing operations risk management; and environmentally friendly processes.

In addition to current ISMI members, who represent over half the world’s semiconductor production, participation in the center is open to all chipmakers, equipment manufacturers, and materials manufacturers. Members derive benefit from interactions with a large network of ESH experts and secure online access to all relevant technical project information and reports. Members will also be able to influence the direction of projects by participating in the Program Advisory Group (PAG) and topical working groups.

Energy conservation is a high priority

The SEMATECH/ISMI community has been pursuing energy and resource conservation since the mid-1990s. Sites have trimmed costs by designing and optimizing their central facility systems using such traditional techniques as HEPA velocity, exhaust, and nitrogen reduction; load matching with variable speed drives; high-efficiency motor use; ultrapure water recycle
eclaim; and chiller plant optimization. However, implementing reduction initiatives for process tools — identified as the greatest energy users — has been slow:

  • Many fear that change will impact yield.
  • Operating fabs do not have the flexibility or risk tolerance to adopt unproven techniques.
  • The diversity of processes and tool configurations has limited comparisons of the energy efficiency of different pieces of equipment.
  • The responsibility for optimizing component energy is unclear, since customers can purchase support equipment (e.g., vacuum pumps) separately from the mainframe.

ISMI has been addressing some of these issues by developing standardized energy measurement tools such as the Total Equivalent Energy (TEE) calculator harmonized with SEMI S23, Guideline for Conservation of Energy, Utilities and Materials. Additionally, ISMI has conducted feasibility and demonstration projects to reduce energy consumption during idle mode (i.e., when no wafer is being processed).


Figure 1.Wafer event analysis results.
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In 2008, ISMI examined the feasibility of reducing plasma-based tool energy consumption during idle mode. A wafer event log was analyzed to track wafer location and event durations to assess potential idle opportunities for various tool components. The analysis showed that, for single wafer tools, there is a wafer-to-wafer idle time in addition to the cassette-to-cassette idle time that the factory normally tracks. The analysis revealed, for example, that a wafer is in the process chamber only 35% of the time (Fig. 1).

This implies that the process chamber is empty 65% of the time, during which the chamber pump could be idled. However, after the wafer is removed, a chamber clean begins that requires vacuum levels similar to processing. Therefore, the time available to idle a chamber pump is actually 50%. While the chamber’s idle time is 50%, individual idle periods may be only 12 seconds. The analysis highlighted the importance of response time (e.g., return to design speed) when deciding to implement idle mode. While the 2008 study aimed to quantify how long a typical pump is idle, work in 2009 will focus an actual pump demonstration in which a speed control strategy will be implemented and the results and impact measured.

Green manufacturing is catching on

The United State’s Green Building Council’s Leadership in Energy and Environmental Design (LEED) Green Building Rating System is a voluntary certification program for new and existing commercial, institutional, or residential buildings [1]. The “LEED Building” designation and associated levels of certification (Silver, Gold, and Platinum) are awarded to buildings that meet certain LEED criteria such as energy efficiency, water usage, site sustainability, construction materials, and indoor environmental quality.


Figure 2.Growth of LEED projects at ISMI members.
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Through the concerted efforts of ISMI and its members, interest in LEED has steadily grown. The ISMI network of fabs and assembly test facilities now claims at least eleven LEED-registered or certified projects — steady growth from the first LEED-registered fab project in 2003 (Fig. 2).

ESH risk assessment essential

The development of advanced semiconductor technologies frequently calls for new and novel process materials. A key challenge of these materials is that they often are invented for the semiconductor industry alone; consequently, their potential effects on the environment or human health are not well characterized. ESH implications of these materials must be assessed early in the R&D cycle (Fig. 3), because the discovery of harmful ESH effects after introduction into manufacturing could result in environmental or personnel exposure risks, production delays, and significant costs.


Figure 3.Process development timeline.
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A new generation of materials — nano-materials — requires special attention. Because these very small materials have unique surface properties, they may exhibit as yet poorly understood, toxic biological effects on the environment and/or humans. Projects at the ESH Technology Center, in partnership with a major semiconductor equipment supplier and the National Institute of Occupational Safety and Health (NIOSH), will study potential nanoparticle exposures resulting from chemical mechanical planarization (CMP) operations.

Slurries used in CMP contain nanoparticles that contribute to the efficiency of the process step. Center studies will evaluate particles released from the slurry into the fab during normal operations and will look at potential personnel exposure scenarios during routine maintenance. The fate of nanoparticles contained in wastestreams will also be evaluated.

Evolving regulatory issues are critical

With semiconductor manufacturing operations located around the globe, identifying and addressing ESH issues is critical to the industry’s success. World-wide ESH regulations on climate change, chemical stewardship, and sustainable development are evolving. The ESH Technology Center aims to provide members with technical solutions for many of these regulatory challenges.

For example, the U.S. EPA published its proposed Mandatory Greenhouse Gas Reporting Rule in April 2009. This rule lays the foundation for future EPA actions limiting GHG emissions; it also may be adopted by other countries. The EPA’s proposed rule [2] will impact semiconductor manufacturing facilities with an annual production capacity >1,080 m2 of silicon, affecting:

  • Etch-related GHG emissions and byproducts;
  • Chemical vapor deposition (CVD)-related GHG emissions and byproducts;
  • N2O emissions (i.e., N2O used = N2O emitted);
  • Fluorinated heat transfer fluids;
  • CO2, N2O, and CH4 combustion-related emissions, if any.

If facilities have an annual capacity > 10,500m2 of silicon, they must estimate emissions using process-specific GHG utilization and byproduct formation factors rather than the default factors in the rule. Use ISMI’s Guideline for Environmental Characterization of Semiconductor Process Equipment [3] to calculate process-specific emission factors.

The European Union’s Registration, Evaluation and Authorization of Chemicals (REACH) regulation fundamentally changes chemicals regulation and use in the EU. REACH places the burden of proof that a substance is safe on the chemical supplier; it also requires that downstream users communicate their use of chemicals to their suppliers. ISMI has partnered with the European Semiconductor Industry Association (ESIA), the Semiconductor Environmental, Safety and Health Association (SESHA), and Semiconductor Equipment and Materials International (SEMI) to ensure the supply chain is aware of its obligations under REACH and partners in developing solutions for the industry.

Click here to enlarge image

Product regulations such as the EU’s Energy-using Products (EuP) Directive, customer requests for information on the environmental impacts of products, and the desire for sustainable manufacturing have led the ESH Technology Center to undertake a project to develop Key Environmental Performance Indicators (KEPIs) that identify and quantify the key environmental impacts of a semiconductor device. ISMI has developed a preliminary list of KEPIs (Table 1) and is now drafting guidelines to further define and calculate a baseline value for each.

Conclusion

ISMI’s ESH program was initiated in 1993. By fostering close collaboration among its various stakeholders, the Center will strive to address current ESH technology issues — energy conservation, materials risk assessment, regulations — by leveraging available ESH funds, preventing duplication of efforts, and providing opportunities for benchmarking.

References

  1. U.S. Green Building Council, http://www.usgbc.org/DisplayPage.aspx?CategoryID=19.
  2. EPA Mandatory Reporting of Greenhouse Gases; Proposed Rule, Federal Register, Vol. 74, No. 68, April 10, 2009.
  3. C. Lausch, M. Sherer, Walter Worth, Guideline for Environmental Characterization of Semiconductor Process Equipment, SEMATECH Technology Transfer #06124825A-ENG, December 20, 2006.

Acknowledgment

Leadership in Energy and Environmental Design (LEED) Green Building Rating System is a registered trademark of the US Green Building Council.

Ron Remke received his PhD in electrical engineering from The U. of Texas at Austin and an MBA from Purdue U. He is the program manager, ESH Technology Center, at ISMI, 2706 Montopolis Drive, Austin, TX 78741 USA; ron.remke@ismi.sematech.org.

Tom Huang received his BS in mechanical engineering from The U. of Texas at Austin. He is the project manager for Resource Conservation at ISMI.

Steve Trammell received his BS in mechanical engineering and MBA from The U. of Texas in Austin. He is the project manager for ESH Assessments at ISMI.

Laurie Beu received her BS in civil engineering from The U. of Texas at Austin and is the project manager for ESH Global Strategies at ISMI.

Walter Worth received his PhD in chemical engineering from MIT and is a consultant to the ESH Technology Center at ISMI.