was technically approved by the global Photovoltaic Technical Committee. This
edition was approved for publication by the global Audits and Reviews
Subcommittee on September 12, 2011. Available at www.semiviews.org and
www.semi.org in October 2011.
Secondary ion mass spectrometry (SIMS)
can measure the total bulk concentrations of oxygen, carbon, boron and
phosphorus in polished solar silicon wafers and silicon feedstock. Bulk carbon
is important because it can form carbon-related defects, such as SiC inclusions.
Bulk oxygen is important in boron-doped silicon because a BOx defect
can degrade cell efficiency. Boron and phosphorus are common dopants in solar Si
wafers, and are difficult to measure directly in solar Si wafers, especially in
highly compensated silicon.
The measurement of all four elemental
concentrations can be accomplished in one test and using one SIMS instrument
equipped with a cesium primary ion source.
The SIMS method can be used at three
stages of solar Si wafers and silicon feedstock: research and development;
process check; and verification at the commercial sales/purchase
SEMI MF2139 — Test Method for Measuring Nitrogen
Concentration in Silicon Substrates by Secondary Ion Mass Spectrometry