Overview
ISO 14237:2010 - Surface chemical analysis - Secondary‑ion mass spectrometry (SIMS) - specifies a standardized SIMS method for the quantitative determination of boron atomic concentration in single‑crystalline silicon using uniformly doped materials. The procedure covers calibration of laboratory (secondary) reference materials (bulk RMs) against a certified, ion‑implanted primary reference material (CRM) and is applicable to boron concentrations from 1 × 10^16 to 1 × 10^20 atoms/cm^3.
Key topics and technical requirements
- Measurement principle: Use of an oxygen (O2+) or caesium (Cs+) primary ion beam to sputter the silicon surface and mass‑analyse emitted secondary ions (B isotopes or B–Si molecular ions).
- Reference materials: Calibration requires a CRM (ion‑implanted boron in Si, e.g., NIST SRM 2137 at time of publication) to derive an isotopic relative sensitivity factor (RSF) and laboratory bulk RMs (RM‑A, RM‑B, RM‑C for low/mid/high dopings and RM‑BG for background).
- Bulk RM requirements: Single‑crystal or epi silicon wafers (≈100 μm epitaxial layer if used), uniformly doped with natural‑isotopic boron and with boron gradient < 5 % per cm.
- Detected species: For O2+ primary beam detect 10B and 11B; for Cs+ detect 10B28Si+ and 11B28Si+. Silicon ion species are measured as reference signals.
- Calibration & calculation: Measure depth profiles of CRM (ISO 17560 procedures) and compute RSF (ISO 18114) from integrated ion intensity ratios and known implanted dose Φimp.
- Measurement practice: Mirror‑polished specimens, detector saturation avoidance (reduce primary current if B > 1×10^5 counts/s), multi‑cycle measurements at multiple positions, and use RM‑BG for background subtraction.
- Quality & performance: Annex C provides apparatus performance checks and linearity tests; Annex A/B cover resistivity → carrier density and isotope‑ratio considerations.
Practical applications
- Process control and doping verification in semiconductor wafer manufacturing.
- Metrology and calibration of SIMS instruments for accurate boron profiling.
- Failure analysis and R&D where precise boron concentration in silicon is required.
- Establishing lab‑level working reference materials for routine SIMS analyses.
Who should use this standard
- SIMS operators and surface analysis laboratories
- Semiconductor manufacturers and process engineers
- Materials metrology labs and calibration facilities
- R&D teams working on silicon doping and device fabrication
Related standards
- ISO 17560 - SIMS method for depth profiling of boron in silicon (referenced for depth‑profile practice)
- ISO 18114 - Determination of relative sensitivity factors from ion‑implanted reference materials (used for RSF calculation)
Keywords: ISO 14237:2010, SIMS, secondary‑ion mass spectrometry, boron concentration, silicon, calibrated reference materials, CRM, RSF, NIST SRM.
Open preview (PDF)Surface chemical analysis — Secondary-ion mass spectrometry — Determination of boron atomic concentration in silicon using uniformly doped materials
