By Lubab Sheet and Eddy Blokken, SEMI

Photovoltaic (PV) and semiconductor may share a common wafer material in silicon, but there are significant differences in manufacturing between the two industries as shown below. Nonetheless, the key challenge facing the PV industry is to decrease costs— there is a firm belief that standardization can help drive down manufacturing costs as it has done in the semiconductor industry. There may even be some existing semiconductor standards that could be modified for PV and implemented fairly quickly. However, they may not be the standards most of the semiconductor industry thinks.

	Photovoltaic	Semiconductor
Number of process steps	>10	>800
Throughput of a typical factory (wafers/day)	>20,000	>2,000
Cycle time	Hours–days	1–3 months
Value of wafer	~ 1 €	~ 100–250 €
Value of product (cell versus processed wafer)	~ 2–3 €	~ 4,000–10,000 €

Source: Kevin Reddig, Franhofer Institute, SEMI 1^st PV Fab Managers Forum, March 2007

First, the standards needs for mono and multi-crystalline silicon PV and thin-film PV are different. Given that silicon wafers makes up more than 90 percent of the PV market today, and the technology is more mature, this is the current focus. Materials handling is a top standards priority along with equipment interfaces—focused on process, not technology standards. Standards are needed for interfaces, input/output elements, safety and possibly intellectual property. The four key application areas for standards in PV are:

• Computer integrated manufacturing
• Carriers
• Equipment hardware and software interfaces
• Facilities and safety

Standards for wafer size or wafer thickness are not viewed as value-add by the mono and multi-crystalline silicon PV community. There are already de-facto standards for the industry, so this is not an area that will garner much interest¹, a very different mind set than the semiconductor industry. One speaker noted, “there is too much potential for innovation on substrates.” And here lies the dilemma: some cell manufacturers are concerned that standardization will limit innovation, and reduce the momentum in the industry. This is an erroneous perception from the viewpoint of SEMI and many of its members. There is no industry in the world with more innovation than the semiconductor industry, and standards have been a key to success from the beginning; eliminating variability in processes to allow companies to focus on innovation. Reducing the number of options in a process to the most significant values allows companies to move faster in new areas of optimization and as such improve process controllability.

Therefore, standards don’t hinder innovation, they guide and foster it!

Standards could also help to bring the PV and semiconductor communities closer together to engage in meaningful, mutually beneficial activities. SEMI and the European Photovoltaic Industry Association will hold a PV standards meeting as part of the European Spring Standards Event in Annecy, April 26, 2007. Individuals interested in participating should contact Eddy Blokken at Eblokken@semi.org or Bettina Weiss at BWeiss@semi.org.

¹ Note that for thin-film PV, there is a need for standards on substrate size and thickness because there are currently many different sizes used.