ICP-MS：Inductively Coupled Plasma - Mass Spectrometry
Features
Because ICP-MS analyses solutions, solidstate samples that are otherwise difficult to prepare as standards can be analysed relatively easily, for example, inorganic trace elements.
- The possible low mass concentrations, parts per trillion (ppt) or sub-ppt levels, are detectable due the high sensitivity and low background signal
- Small uncertainty in quantitative analysis thanks to flexibility in preparation of the reference solution
- Qualitative analysis possible because many elements in the periodic table can be measured simultaneously
- Wide dynamic range allows simultaneous analysis of both major and minor components
Application Examples
- Metal contamination on Si wafer surfaces
- Quantitative analysis of metal impurities in thin films such as SiOx
- Contamination assessment of clean rooms
- Quantitative analysis of impurities in solutions (ultra-pure water, high-purity reagents)
- Quantitative analysis of elemental impurities in powders and bulk (e.g., Si, quartz)
- Compositional analysis of thin films (oxide films, metal films, etc.)
- Compositional evaluation of alloys
Principle
ICP-MS measures the ionic strength of a particular mass/charge ratio (m/z). Argon plasma is generally used as the ion source. Argon plasma is obtained by passing argon through a quartz triple tube wound with induction coils through which high-frequency currents flow. Because of the very high gas and electron temperatures (about 6000-10000 K) , the plasma can ionize more than 90% for many elements. After ionization, the mass/charge ratio is measured by a quadrupole mass spectrometer. Many metals are introduced into the mass spectrometer as +1 valent ions.
Since naturally occurring elements have a constant isotopic composition, a qualitative analysis of the contained elements can be performed by scanning the ionic strength of each m/z. Since the ionic strength is proportional to the amount of contained elements, quantitative analysis can be performed by comparing the ionic strength with a standard solution of known concentration.
Data examples
Further features:
- Monitoring of constituent element ratios in thin-films for growth process optimization
- In-plane distribution evaluation of constituent element ratios by spatial sampling
Data delivery format
Portable Document Format (PDF) file
Specifications
Items for enquiries
- Sample information
- Number of samples, and availability of preliminary samples
- Shape and morphology (size, bulk, thin film, liquid, etc.), layer structure and film
thickness (for thin film samples), element of interest, expected concentration, and unit
of data to be submitted (wt%, at%, g/g, g/cm2, atoms/cm2, etc)
- Handling instructions
- Details on delivery
- Preferred due date for preliminary analysis report
- Due date for delivery of final report
- Priority in the case of a large number of samples
- Any other issues
Caution
- Preliminary samples may be required
- There are elements that are difficult to pre-treat/measure depending on the condition of the compound
- If it cannot be dissolved, the assay is not possible
- The reported value of qualitative analysis is a guide to the content
- Quantitative analysis is appropriate when handling values strictly
［ICP-MS］誘導結合プラズマ質量分析法の分析事例はこちらからご覧ください。