Optical thickness determination on transparent granulates

01.07.2010 - 30.06.2013
Research funding project
Intermediate layers with thicknesses in the nanometer range (0.5 - 100 nm) play a crucial role in several technological processes as e. g. microelectronic multilayer systems and magnetic storage. In these cases the determination of the layer thickness, which controls the physical properties of the coatings to a high degree, is, although not trivial, well established. On the other hand interlayers are applied to an increasing extent to modify the surface properties of fibrous, granular and other irregularly shaped bodies. Here the determination of the thickness of the modifying layer is much more complicated and reliable methods of thickness measurement are rare. Prominent examples in this respect are copper diamond composites with their extremely high thermal conductivities of more than 600 W/mK in combination with a Coefficient of Thermal Expansion (CTE) which can be matched to the CTE of commonly used electronic materials (4 - 8 ppm/K). The weak point of this material is the Thermal Contact Resistance (TCR) at the interface between the Copper matrix and the diamond particles dispersed therein. A method to influence the TCR is the introduction of an intermediate layer which improves the thermal transfer between the constituents. The thickness of this layer is of crucial importance. It has to be thick enough to significantly alter the physical properties of the interface and thin enough not to act as a contamination of the composite. These requirements lead to interlayer thicknesses in the range of 100 nm and below which means that also metallic layers become optically transparent. It is the aim of this project to exploit the fact that both, the granulate (diamond particles) and the surface modification layer are transparent to electromagnetic radiation in the vilsible range. The aim of the project is to develop a fast, cost effective method to determine film thicknesses on a large number of diamond particles with high spatial resolution. The optical density of the coated diamond particles is dependent on the thickness of the surface modification layer and can be quantifued with high spatial resolution (as low as 8 µm) with a high quality optical scanner. Starting from existing pattern recognition techniques for the characterization of granular and fibrous materials algorithms shall be developed which not only yield information on the coating thickness on single diamond grains but also on statistically significant ensembles of grains which allow for the determination of e. g. coating uniformity. Based on these results also the thickness of transparent coatings on spherical and fibrous transparent particles will be investigated for statistically significant particle ensembles.

People

Project leader

Project personnel

Institute

Grant funds

  • FWF - Österr. Wissenschaftsfonds (National) Austrian Science Fund (FWF)

Research focus

  • Surfaces and Interfaces: 50%
  • Materials Characterization: 50%

Keywords

GermanEnglish
SchichtdickeLayer thickness
Optische TransmissionTransmission optic
Kupfer Diamant KompositCopper Diamond Composite
Transparentes GranulatTransparent granulate
MustererkennungPattern recognition

Publications