Thin Film Analysis

X-ray thin film analysis is an established technique for the determination of the film thickness, structural parameters, composition and strain.

Film thickness can range from sub-nanometer to millimeter.

According to the film type, different X-ray techniques will be used in order to determine the parameters of interest.

1. X-ray reflectivity

X-ray reflectivity is based on the constructive interference of X-rays scattered from the surface of the thin film and the different interfaces between the sublayers of the multilayer stacks. Measuring and fitting the XRR curves with proprietary Sirius-XRR state-of-the-art software analysis program will allow determination of:
  • Layer thickness of thin films and multilayers.
  • Layer and interface roughness.
  • Surface density gradients and layer density.
  • Interfacial structures.
  • Layers/Films uniformity across the wafer.

Technical Specifications:

  1. Minimum thickness ~ 1,5 nm
  2. Maximum thickness up to ~ 300 nm.
  3. Resolution ~ 1% of the measured thickness
  4. Lateral resolution (minimum spot size ~ 1 cm)
Example: Al2O3/InGaAs film on Si substrate

2. High Resolution X-ray Diffraction

High Resolution X-ray Diffraction (HRXRD) is used for the characterization and process development of epitaxial thin films and multilayers like: SiGe, SOI, epitaxial GaN on Si, photonics materials, III/ V in general, epitaxial complex oxides. Different HRXRD techniques are used:
Example: Rocking Curve of epitaxial layer
Example: Theta/2Theta scan of GaN layered structure

3. Reciprocal space maps

Two dimensional reciprocal space maps for a rapid determination of three dimensional structural parameters by measuring and analysing and area of the reciprocal space.

4. In-Plane Grazing incidence

In-plane grazing incidence diffraction* is a technique used for fast determination of in-plane lattice parameters of ultra-thin epitaxial films, structural registry of the layer with respect to the substrate, lateral crystalline film quality.

*Als-Nielsen, J. & McMorrow, D. (2011). Elements of Modern X-ray Physics (2 ed.). Wiley. ISBN 978-0470973950.

5. Grazing incidence powder diffraction. Structural Phase Identification of thin polycrystalline layer.

X-ray diffraction under grazing incidence reduces the penetration depth of the incoming X-rays and thus allows measurements of nanometer thin films excluding part of the signal coming from the substrate.

6. Semiconductor Wafer Mapping

Wafer homogeneity (composition, thickness, strain) maps can be performed up to 200mm in a R&D environment. No clean room.