By James Amano, Director, International Standards, SEMI

There are now over 30 PV standardization efforts underway at SEMI. This may not seem like a lot when compared to the nearly 800 SEMI Standards for semiconductor manufacturing, but the formation of the first PV Standards Committee happened just a few years ago in 2007. In that short time, the global PV industry has recognized the need for standards to drive down manufacturing costs and increase supply chain efficiency, has selected the SEMI time-tested open platform to create and disseminate these standards, and has released and implemented several of these standards. Noting the impact that semiconductor industry standards have had on reducing manufacturing cost and increasing supply chain efficiency over the past 40 years, Gerhard Rauter, the Chief Operating Officer of Q-Cells said, “SEMI has a long history of successful standardization; this is why SEMI is the preferred platform to develop the standards needed to drive down PV cell manufacturing cost.”

It also did not take long for the PV standards effort to go global. A North American PV Standards Committee followed shortly after the European Committee started, and there are now committees in Japan and Taiwan with working groups forming in China and India. The PV industry recognized that although many PV-specific standards existed for end products, at that time the PV industry had almost no standards to support manufacturing. The case then, as it is now, was that the PV market was large and growing rapidly, with many new entrants and a global supplier and customer community. A common base of manufacturing standards was required to make PV viable as a cost-effective and renewable global energy source.

The original committee quickly identified several high-priority challenges, including increasing yield of existing equipment, reducing equipment downtime, and reducing ramp-up time. To address these (and other) issues, the initial focus of the committee was to streamline interfaces and communication between manufacturing equipment. To this end, the PV Equipment Interface Specification (EIS) Task Force (TF) was formed to develop a set of standards defining the IT equipment interface for PV equipment, with overall goals of reducing costs for equipment investment, installation, integration and testing, reducing time-to–production, and improving manufacturing data quality.

By early 2009, the EIS TF had developed SEMI PV2 — Guide for PV Equipment Communication Interfaces, a significant industry milestone, which defines a unified equipment communication interface for PV production systems. SEMI PV2 provides multiple benefits to the PV industry, including shorter manufacturing ramp-up time, increased functionality, simplified requirement specifications, and increased potential cost savings for manufacturers. The EIS TF is now working on a specification for single substrate tracking (covering crystalline and thin film applications), including the issue of equipment-to-equipment communication (also called “horizontal communication”). This committee has strong industry support and participation from both Europe and Japan.

Another identified need was for material characterization, including test methods. The total annual volume of silicon feedstock that goes into silicon solar cells now exceeds the total annual volume of polysilicon used in the semiconductor industry. A major problem with sourcing this large quantity of material, though, has been the lack of a standardized test method for detecting elemental impurities in photovoltaic silicon feedstock. This is critical, as the purity level of the beginning material can have a significant impact on solar cell efficiency and the productivity of some processes used to transform the PV Si feedstock into solar cells. The International PV Analytical Test Method Task Force was chartered to tackle these problems. The Task Force’s first published output, SEMI PV1 — Test Method for Measuring Trace Elements in Silicon Feedstock for Silicon Solar Cells by High-Mass Resolution Glow Discharge Mass Spectrometry is the first standard test method that specifically addresses the evaluation of some types of PV Silicon feedstock. By standardizing this test method, the PV industry now has an international “ruler” that can be used when specifying and qualifying material.

The publication of these two milestone Standards underscored the value of SEMI Standards to the PV industry, and the number of Standards-related activities has since grown rapidly. For example, the Gases and Chemicals TF formed to defining the purity requirements of materials used by manufacturers of solar cells, and just recently published its first Standard, PV3 — Guide for High Purity Water Used in Photovoltaic Cell Processing. This TF is now working on guides for several other critical chemicals used in PV.

Silicon feedstock is another key area, as the increasing number of players in the market for feedstock materials has introduced a wide variety of material grades. This requires considerable efforts of the parties involved to achieve a common understanding of the material specifications and the impacts of the different materials on the resulting PV product quality and performance. As standardized specifications of these materials are highly desirable, the Silicon Materials Task Force is currently working on a Specification for Solar Grade Si Feedstock Materials, which will go through the first step of standards approval as it is balloted later this spring.

Automated material handling is a prerequisite for efficient PV module fabrication, and the PV Transport Carrier Task Force is looking at Standards needed for PV wafer and cell carriers. The current reality is that PV manufacturers and equipment suppliers are spending significant time and effort on material handling within their production lines, distracting them from focusing on their core competencies. This Carrier TF effort, led by Q-Cells, will also enable standardization of equipment load ports and transport systems, resulting in both direct and indirect cost savings throughout the whole supply chain, less risk during ramp-up, and less effort for integration of production lines.

In addition to the above activities, other standardization work at SEMI is addressing areas as diverse as thin film substrate dimensions, module vibration testing, and transparent conductive oxide. This wide range of activities is now too broad to be handled by a single committee, and a new SEMI PV Automation Standards Committee will be formed soon in Europe and Japan to focus on both software and mechanical automation issues.

We also have found that many existing SEMI semiconductor manufacturing Standards are already being used by the PV industry. In addition to test methods and material specifications, Standards such as SEMI E10 — Specification for Definition and Measurement of Equipment Reliability, Availability, and Maintainability and SEMI F47 — Specification for Semiconductor Processing Equipment Voltage Sag Immunity have proven their value to the PV industry. EHS is also an important area, and initial industry feedback indicates that manufacturing equipment for crystal silicon solar cells could be covered by SEMI S2 — Environmental, Health, and Safety Guideline for Semiconductor Manufacturing Equipment, and thin film manufacturing could be covered by SEMI S26 — Environmental, Health, and Safety Guideline for FPD Manufacturing Systems. Of course, many PV-specific issues exist for EHS, such as explosion and fire risk due to more hydrogen use. These specific requirements are being investigated by the EHS Standards Committee’s PV Study Group, which includes members from the SEMI EHS and PV Standards Committees.

The SEMI PV Standards Program is now truly global, with committees in Europe, Japan, North America, and Taiwan. Given the major role of China in PV, efforts to establish a Chinese SEMI PV Standards Working Group are underway. A Standards Workshop will be conducted at this summer’s SOLARCON India to engage the technical experts in this fast-growing region. With offices and staff in all major PV manufacturing regions of the world, only SEMI could provide the global support necessary for the success of these efforts.

SEMI offers that support, but companies in the industry donate the manpower. These Standards were the work of volunteers – in fact, over 400 technical experts from leading companies in all sectors of the global PV manufacturing supply chain are now engaged in developing PV Standards at SEMI. Critical mass is forming around many of these efforts, but more industry participation is needed to develop the critical Standards required to make grid parity a reality. If you or your company is not yet involved in these efforts to shape the future of PV, now is the perfect time to register, as committees and task forces will be meeting globally throughout the spring and summer. To learn more, please visit www.pvgroup.org/standards and www.semi.org/standards, or contact your local Standards staff.

Participation in the SEMI Standards Program is free, but member registration is required. www.semi.org/standardsmembership.

PV Group, The Grid – April 2010