SEMI publishes new PV standard for silicon feedstock

SAN FRANCISCO, USA: SEMI announced a new standard to specify silicon feedstock for photovoltaic (PV) manufacturing. SEMI PV17-0611 covers virgin silicon feedstock materials produced by chemical vapor deposition (CVD) processes, metallurgical refining processes, or other processes.

CVD processes include the so-called “Siemens process,” fluidized bed processes, powder processes, and other processes using distilled silane or halosilane compounds. These specified materials are intended for growing of single crystalline ingots and casting, or other methods of growing multicrystalline Si, used for producing Si wafers for solar cells.

There are now a total of 17 published SEMI Standards for photovoltaics manufacturing, and there are over 25 additional PV standardization efforts underway. Since 2007, over 400 PV industry experts in more than 20 task forces have developed and published SEMI PV standards covering equipment, materials, and test methods used in crystalline cell, module and thin-film manufacturing processes.

SEMI PV17-0611: Specification for virgin silicon feedstock materials for PV apps
The increasing number of players in the market for PV silicon feedstock materials has introduced a wide variety of material grades— which require considerable efforts from both suppliers and end users to achieve a common understanding of the material specifications, as well as the impacts of the different materials on the quality and performance of the resulting PV product.

SEMI PV17 specifies the feedstock materials to be used for growing silicon ingots, creating a well-defined reference in a growing market by reducing many individual specifications to the four categories defined in the standard. It also defines the terms used, which will minimize misunderstandings between supplier and user. The standard also will help to reduce variations of material quality.

“The SEMI Standards PV Silicon Materials Task Force developed this standardized specification for solar grade feedstock materials, which will allow manufacturers to produce consistent silicon solar cells,” said James Amano, senior director, SEMI Standards and EHS, “We are pleased that the specification received input from major polysilicon suppliers from around the world. Industry consensus is very important to the standards development process.”

By using this specification, polysilicon and cell manufacturers can specify chemical (donor concentration), dimensional (chunk, rod, bricks), and packaging characteristics on their purchase orders for feedstock materials. In addition, PV17-0611 also lists the test methods to validate the specified characteristics.