Thin Film Analysis
- Multi-element detection for chemical information across a surface or for depth profiling through layers
- High speed detection
- High mass resolution allowing you to separate interfering ions
Thin Film Analysis and Characterization
Thin films are part of our daily life and are used in a wide variety of applications, such as special glass coatings for light emitting devices and optical mirrors, electronic devices in computers, memory storage devices, and solar cells. Thin films are a layered material manufactured at the nanometer to micron scale.
Femtosecond laser ablation inductively coupled plasma time-of-flight mass spectrometry (fs-LA-ICP-TOFMS) can be used for the determination of the stoichiometry of thin films with high spatial and depth resolution. This analytical technique combines the advantages of femtosecond lasers for precise removal of material with the fast and multi-element detection capabilities of TOFWERK’s icpTOF, yielding chemical information across a surface or for depth profiling through layers.
Secondary ion mass spectrometry has been used for the analysis of thin films since the technique became widely used in the 1970’s. The TOFWERK fibTOF can resolve layers of about 10 nm thickness, and even thinner layers in favorable conditions. The strengths of an imaging SIMS instrument such as the fibTOF for investigating thin films include:
- Small areas within a film can be analyzed, such as defects or device -scale depositions.
- An image obtained in addition to the depth profile – important if the thin film even on small scales is not homogenous.
- The FIB beam can be used to prepare the sample e.g., to remove layers that are bot of interest, or to prepare a complementary cross-sectional view or even full SEM tomography (optionally combined with SIMS information).
For nm depth resolution profiling of inorganic layers plasma profiling time-of-flight mass spectrometry (PP-TOFMS) uses a fast glow discharge plasma sputtering source to erode the surface and generate the depth profiles. Thanks to its high throughput, speed, ease of operation, high dynamic range, full mass coverage and uniform elemental sensitivity, PP-TOFMS is a valuable characterization tool for any process engineer and material scientist.
Depth Profiling of Thin Films Using the fibTOF for FIB-SIMS Measurements
- High speed -all secondary ions, ensuring accurate signal ratios between species
- Depth profiling resolution <10 nm
- High resolution chemical imaging (3D or 2D images, or a depth profile from a region of interest)
- Unambiguous elemental identification with high mass resolving power
- Detection of both negative and positive secondary ions
Results of a FIB-SIMS analysis of a thin film stack using the fibTOF. The figure shows a partial depth profile from a Vertical Cavity Surface Emitting Laser (VCSEL) semiconductor device. The fine structure within the five repeated features between 400 and 2000 rasters of the FIB beam (this axis corresponds to depth) is from material layers less than 10 nm thick.
Close-to-Process Elemental Depth Profiling Using the PP-TOFMS
- High depth resolution. Nanometer thin layers can be resolved.
- High throughput and and ease of use. Without the need to transfer sample in UHV and sputtering rates as high as 40 nm/s, analysis only takes few minutes.
- Semi-quantification in one click/without reference sample. Sputtering and gas phase ionization yield only slightly vary over elements in the periodic table. The ion beam ratio method allows estimation of atomic concentration with an accuracy of a 2-3 factor for most elements.
- Full elemental coverage and high sensitivity. Major elements and dopants can be detected at any point of the depth profile. Identification of fully unknown layers and the detection of unexpected contamination becomes easy.
For more information about the PP-TOFMS, please contact our partner:
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Plasma Profiling Time-Of-Flight Mass Spectrometry (PP-TOFMS)
Plasma Profiling TOFMS
Nolot et al. Accelerating the development of phase-change random access memory with in-fab plasma profiling time-of-flight mass spectrometry. Surface and Interface Analysis, 2020. DOI: 10.1002/sia.6823
Torrengo et al. Quantitative depth-profile analysis of transition metal nitride materials with combined grazing-incidence X-ray fluorescence and X-ray reflectometry analysis. Spectrochimica Acta, 2020. DOI: 10.1016/j.sab.2020.105926
Spende et al. Plasma profiling time-of-flight mass spectrometry for fast elemental analysis of semiconductor structures with depth resolution in the nanometer range. Semiconductor Science and Technology, 2020. DOI: 10.1088/1361-6641/ab6ac0
Mazel et al. Multitechnique elemental depth profiling of InAlGaN and InAlN films. Journal of Vacuum Science & Technology, 2018. DOI: 10.1116/1.5019635
High Resolution Depth Profiling by fs-LA Using the icpTOF
- All the elements. All the time. The icpTOF always records complete mass spectra, so you never miss an analyte or interference signal.
- High mass resolution. The icpTOF 2R has a mass resolving power of 6000 allowing you to separate interfering ions.
- Precise isotope ratios. The icpTOF simultaneously measures all isotopes, thus eliminating the susceptibility of your measurements to source and sample fluctuations. Precision approaches statistical limits.
- High speed detection. The icpTOF records a complete mass spectrum every 12-50 µs making it the optimum detector for fast transient signals such laser ablation pulses.
- Compatibility with major laser companies
- Dedicated workflow for laser ablation