SEMI PV1 - Test Method for Measuring Trace Elements in Silicon Feedstock for Silicon Solar Cells by High-Mass Resolution Glow Discharge Mass Spectrometry
This Standard was technically approved by the Photovoltaic Global Technical Committee. This edition was approved for publication by the global Audits and Reviews Subcommittee on August 18, 2017. Available at www.semiviews.org and www.semi.org in March 2018; originally published March 2009; previously published February 2011.
This Test Method can be used to monitor the bulk trace level elemental impurities in silicon feedstock that affect the performance of the silicon solar cell, in particular,
1. the concentration of intentionally added dopants, and unintentionally added dopants, that can affect the target bulk resistivity of the solar cell wafer,
2. the concentration of metals (e.g., iron) and other impurities that can degrade the minority carrier lifetime of the solar cell wafer.
This Test Method can be used to monitor or qualify Si feedstock to be used in either crystalline or multicrystalline silicon wafer production.
This Test Method can be used for research and development of silicon feedstock processes and products, crystalline and multicrystalline silicon growth processes.
This Test Method can be used to evaluate the failure or reduced performance of crystalline or multicrystalline silicon solar cells.
This Test Method can facilitate a unifying of protocols and test results among worldwide laboratories used for research and development support, monitoring or qualifying product for purchase or sale or internal use.
For most elements the detection limit for routine analysis is on the order of 1 to 100 µg/kg (1 to 100 ppbwt).
This Test Method covers the determination of total bulk concentrations of most of the periodic table (exceptions are atmospheric C, O, N, H and noble gases due to high background signals) in silicon feedstock using a magnetic sector high-mass resolution glow discharge mass spectrometry (HR-GDMS). This Test Method measures the total amount of each element, because this test method is independent of the element’s chemistry or electrical activity in the silicon.
This Test Method does not include all the information needed to complete HR-GDMS analyses. Sophisticated computer-controlled laboratory equipment, skillfully used by an experienced operator, is required to achieve the desired sensitivity. This Test Method does cover the particular factors (e.g., specimen preparation, setting of relative sensitivity factors, determination of detection limits) known to affect the reliability of direct trace element analysis.
This Test Method can be used for silicon in a range of physical forms, including polysilicon powders, granules, flakes, chunks, and single and multicrystalline wafers and slugs. This Test Method can be used for silicon feedstock irrespective of all dopant species and concentrations.
This Test Method is especially designed to be used for bulk analysis of silicon feedstock with elemental concentrations in the range of ppbwt to ppmwt.
The limit of detection is determined by either the BLANK value or by count rate limitations, and may vary with instrumentation.
Referenced SEMI Standards
SEMI MF28 — Test Method for Minority Carrier Lifetime in Bulk Germanium and Silicon by Measurement of Photoconductive Decay
SEMI MF43 — Test Method for Resistivity of Semiconductor Materials
SEMI MF84 — Test Method for Measuring Resistivity of Silicon Wafers With an In-Line Four-Point Probe
SEMI MF391 — Test Method of Minority Carrier Diffusion Length in Extrinsic Semiconductors by Steady-State Surface Photovoltage
SEMI MF397 — Test Method for Resistivity of Silicon Bars Using a Two-Point Probe
SEMI MF525 — Test Method for Measuring Resistivity of Silicon Wafers Using Spreading Resistance Probe
SEMI MF673 — Test Method for Measuring Resistivity of Semiconductor Wafers or Sheet Resistance of Semiconductor Films with a Noncontact Eddy-Current Gauge
SEMI MF1389 — Test Method for Photoluminescence Analysis of Single Crystal Silicon for III-V Impurities
SEMI MF1535 — Test Method for Carrier Recombination Lifetime in Silicon Wafers by Noncontact Measurement of Photoconductive Decay by Microwave Reflectance
SEMI MF1630 — Test Method for Low Temperature FT-IR Analysis of Single Crystal Silicon for III-V Impurities
SEMI MF1724 — Test Method for Measuring Surface Metal Contamination of Polycrystalline Silicon by Acid Extraction-Atomic Absorption Spectroscopy