二次离子质谱法
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Secondary Ion Mass Spectrometry (SIMS) Analysis
Technical Principle
SIMS enables detection of dopants and impurities at ultra-trace concentrations. This technique provides elemental depth profiling with resolution ranging from angstroms (Å) to tens of micrometers (μm). The sample surface is sputtered by a primary ion beam (typically O₂⁺ or Cs⁺), and the secondary ions generated during sputtering are collected and analyzed using mass spectrometers (quadrupole, magnetic sector, or time-of-flight). The detectable concentration range spans from matrix levels to sub-ppm trace levels.
Key Applications
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Dopant and impurity depth profiling
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Composition and impurity measurement in thin films (metals, dielectrics, SiGe, III-V, and II-VI materials)
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Ultra-high depth resolution profiling for shallow implants and ultrathin films (ultra-low energy implants and gate oxides)
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Bulk concentration analysis including B, C, O in Si
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High-precision matching of process tools (e.g., ion implanters)
Advantages of SIMS
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ppm-level or better detection sensitivity for dopants/impurities
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Excellent detection limits and depth resolution for profiling
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Small-area analysis capability (≥5μm)
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Detection of all elements and isotopes including hydrogen
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Outstanding dynamic range (up to 6 orders of magnitude)
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Applicable for stoichiometric and compositional analysis
Limitations
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Destructive analysis method
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No chemical bonding information
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Samples must be vacuum-compatible solids
Technical Specifications
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Primary ions: O₂⁺ or Cs⁺
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Depth resolution: Å to μm scale
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Detection limits: Sub-ppm to matrix levels
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Mass analyzers: Quadrupole/Magnetic Sector/Time-of-Flight
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Lateral resolution: ≥5μm