Secondary Ion Mass Spectrometry (SIMS)

Secondary Ion Mass Spectrometry (SIMS) is an analytical technique in which the composition of a surface is analyzed using a focused ion beam. When a solid sample is irradiated by an energetic ion beam, the sample surface fragments (atoms and molecules in both neutral or ionic forms) are ejected. The secondary ions (ions among the ejected particles) are analyzed by various mass-spectrometric techniques, which is used to classify the type of the SIMS analysis.

The type of SIMS are:

Time-of-Flight SIMS (ToF-SIMS) separates the ions in a field-free drift path according to their velocity. Since all ions possess the same kinetic energy, the velocity and therefore time-of-flight varies according to the mass of each ionic species. This measurement is achieved by using pulsed ion beams. As it is the only analyzer type that can detect all generated secondary ionic species simultaneously, ToF-SIMS is used for applications that require thorough analysis.
Magnetic sector SIMS (M-SIMS) uses a magnetic sector field to separate the secondary ions by their mass-to-charge ratio. It is usually used in high-speed dynamic mode for selected species. Non-selected elements are not analyzed since they do not reach the detector.
Quadrupole mass analyzer SIMS separates the masses by resonant electric fields which allow only the selected masses to pass through the quadrupole.

To read more on SIMS, you can read our Key Tech brochure.

Services

Surface analysis: To understand the components on the surface area using ToF-SIMS.
Depth profiling: For dopant type identification and profile, diffusion profile, and trace element analysis. M-SIMS is used for relatively thick sample (0.5 ~ 10 um), while ToF-SIMS is used for shallow depth analysis (0.01 ~ 1 um).
Large molecule (such as polymers) identification: Principal Component Analysis (PCA) method using ToF-SIMS.
3D Bio-imaging: For cells of an organ using PCA assisted ToF-SIMS.

Pricing

Pricing for SIMS and other Materials Analysis services are provided on our Pricing Table

FAQ

Q: What are common applications of SIMS?: A: In the semiconductor industry SIMS is used to analyze dopant species and profiles, diffusion profiles, and for trace element analysis. With LEDs, it is used for compositional and structural analysis of p-n layer stack, and analysis of interface and polymer contaminant identification in packaging. It also has applications in Geoscience and Bioscience.
Q: What are the strengths and limitations of SIMS?: A: Strengths: strong lateral and vertical sensitivity, very low detection limit which can go down to ppb level and allows the analysis of isotopic ratios, in-situ analysis that eliminates the need for complex sample preparation, one of the few metrologies that can analyze hydrogen.

Limitations: As SIMS only analyzes ion species from the ejected particles, whose ratios depend on many parameters such as primary beam type, ionization probability of components, and surface's electronic states, the elemental ratio detected doesn’t reflect the actual composition of the sample. Therefore, SIMS results can’t be quantitative and can only be used for the relative comparison of samples within a batch or for the trace element profile analysis.

Equipment

CAMECA IMS 7F-Auto

The Cameca IMS 7F-Auto is designed to for precision elemental and isotopic analyses, and optimized for applications such as glass, metals, ceramics, Si-based, III-V and II-VI devices, bulk materials, thin films, and more.

Read more about the Cameca IMS 7F-Auto here.