Optical characterization techniques real-time applications

Reflectance-based optical characterization techniques offer the advantages of high energy resolution and sensitivity to both macrostructural and microstructural effects while nondestructively providing real-time information with the sample in any transparent ambient. Experimental and analytical methods are discussed, and examples are given to illustrate representative applications to problems of current interest in semiconductor technology. 

Real Time Applications. Optical characterization techniques can provide unique information in real-time applications involving deposition or etching. Line-of-slght access to the sample by both Incident and reflected beams is required. The use of reflectance techniques to monitor material removal, e.g., in plasma reactors, is well known (28 1 the examples selected here will Illustrate less well explored possibilities in deposition. 

The refinement of other analytical methods, such as electrophoresis [34,36], the various techniques of optical spectroscopy [103-105], and nuclear magnetic resonance [201], is supplemented by the recent advances in real-time affinity measurements [152,202], contributing to the understanding of biomolecular reactivity. Taken together, the improvement of analytical methods will eventually allow a comprehensive characterization of the structure, topology, and properties of the nucleic acid-based supramolecular components under consideration for distinctive applications in nanobiotechnology. 

The application of laser light scattering techniques to molecular characterization of dielectric films offers the ability to directly probe chemical bonding within the film and at the film-substrate interface. Real-time measurements can be carried out under ambient conditions or in hostile environments allowing transient film stability studies to be conducted. Such laser-based techniques require only an optically clear line of sight between sample and analyzer and offer several advantages over the high vacuum surface analytical techniques commonly applied to film characterization. These include nondestructive measurement capability, rapid data acquisition time, and ability to use the optical properties of the sample to enhance the sensitivity of the measurement. 

---