Optical properties of semiconductors and ultra thin dielectric layers

Ellipsometry as a characterisation technique for thin films has been seen traditionally as a technique used for the estimation of thin films thickness and optical constraints.

Professor S Hall and Dr I Mitrovic

The recent developments in both hardware, particularly variable angles and the extended spectral range, together with data assessment software, introduce new capability to so-called spectro-ellipsometry. In particular, the characterisation of ultra-thin high-k dielectric films for CMOS application, pose a series of challenges most notably:

  1. Ultra thin films (<4nm thickness) with a structure dependent on the growth or deposition technique used.
  2. Multi-stack structures, due to the presence of a transition layer at the interface between substrate and the metal oxide film and a possible variation in the layer composition.
  3. The lack of reliable information on optical constants for most ultra-thin, novel materials.

The group also has access to advanced FTIR capability.

We are pursuing research into new analytical approaches to the application of spectro-ellipsometry to these ultimate challenges. The techniques are also applied to the study of biological materials through collaboration with the bionanoengineering group.

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