Rutherford Backscattering Spectrometry
Rutherford Backscattering Spectrometry (RBS) is an ion scattering technique used for compositional thin film analysis. RBS is unique in that it allows quantification without the use of reference standards. During an RBS analysis, high-energy (MeV) He2+ ions (i.e. alpha particles) are directed onto the sample, and the energy distribution and yield of the backscattered He2+ ions at a given angle is measured. Since the backscattering cross section for each element is known, it is possible to obtain a quantitative compositional depth profile from the RBS spectrum obtained for films that are less than 1 μm thick.
In addition to elemental composition, RBS can be used to obtain information on the crystalline quality of single crystal samples. This technique, called “channeling,” can probe the degree of damage in a crystal or determine the amount of substitutional or interstitial species in a lattice.
Atomic Echo Labs has world-class experience in analyzing thin films using Rutherford Backscattering Spectrometry, with both pelletron and tandetron instrumentation. Atomic Echo Labs experience in the analysis of all types of thin films (oxides, nitrides, silicides, high and low-K dielectrics, metal films, compound semiconductors and dopants) enables fast turnaround times, accurate data, and high quality person-to-person service.
This icon represents Rutherford Backscattering Spectrometry (RBS) performed by scientists at Atomic Echo Labs
Ideal Uses of Rutherford Backscattering Spectrometry
- Thin film composition/thickness
- Determine areal concentrations (atoms/cm2)
- Determine film density (when thickness is known)
Strengths
- Non-destructive compositional analysis
- Quantitative without standards
- Conductor and insulator analysis
- Hydrogen measurements (in HFS mode)
- Low-Z element sensitivity (in NRA mode)
Limitations
- Large analysis area (~2 mm)
- Useful information limited to top ~1 μm of samples
Rutherford Backscattering Spectrometry Technical Specifications
- Signal Detected: Backscattered He atoms
- Elements Detected: B-U
- Detection Limits: 0.001-10 at%
- Depth Resolution: 100-200 Å
- Imaging/Mapping: No
- Lateral Resolution/Probe Size: ≥ 2 mm