- SEMI MF2139 - Test Method for Measuring Nitrogen Concentration in Silicon Substrates by Secondary Ion Mass Spectrometry
This Standard was technically approved by the Silicon Wafer Global Technical Committee. This edition was approved for publication by the global Audits and Reviews Subcommittee on February 1, 2016. Available at www.semiviews.org and www.semi.org in April 2016; originally published by ASTM International as ASTM F2139-01; previously published January 2010.
Secondary ion mass spectrometry (SIMS) can measure in un-annealed, polished Czochralski (CZ) silicon substrates the nitrogen concentration that may be intentionally introduced to: (1) increase the V/G tolerance for grown-in defects free region, where V is the pull rate and G is the crystal temperature gradient at the solid-liquid interface; (2) increase the void-free denuded zone depth and the bulk micro-defect density after annealing in hydrogen or argon; (3) reduce the crystal originated particle (COP) size after annealing; or (4) enhance the precipitation of oxygen in epitaxial substrates under reduced temperature processing.
SIMS can measure total bulk nitrogen in CZ-silicon, whereas infrared spectroscopy is negatively affected by the chemical state in oxygen-containing silicon. In addition, SIMS can measure the total bulk nitrogen in p+(B) and n+(Sb) substrates used for epitaxial silicon, whereas infrared spectroscopy cannot due to free electron absorption interferences.
SIMS can measure in un-annealed, polished Float-zoned (FZ) silicon substrates the nitrogen concentration that may be introduced to strengthen low oxygen substrates.
The SIMS method can be used for process check of crystal doping, and for research and development.
This Test Method covers the determination of total nitrogen concentration in the bulk of single crystal substrates using secondary ion mass spectrometry (SIMS).
This Test Method can be used for silicon in which the dopant concentrations are less than 0.2% (1 × 1020 atoms/cm3) for boron, antimony, arsenic, and phosphorus.
This Test Method is for bulk analysis where the nitrogen concentration is constant with depth.
This Test Method can be used for silicon in which the nitrogen content is 1 × 1014 atoms/cm3 or greater. The detection capability depends upon the SIMS instrumental nitrogen background and the precision of the measurement.
This Test Method is complementary to infrared spectroscopy, electron paramagnetic resonance, deep level transient spectroscopy, and charged particle activation analysis. The infrared spectroscopy method detects nitrogen in specific vibrational states, rather than total nitrogen, and is limited to silicon with doping concentrations less than about 1 × 1017 atoms/cm3. The charged particle activation analysis detection capability is limited by an interference from boron.
Referenced SEMI Standards