We show that thermal wave detection and analysis can be performed, in a noncontact and highly sensitive manner, through the dependence of sample optical reflectance on temperature. Applications to the study of microelectronic materials are illustrated by an example of measuring the thickness of thin metal films.

A new technique has been developed that employs highly focused laser beams for both generating and detecting thermal waves in the megahertz frequency regime. This technique includes a comprehensive 3-D depth-profiling theoretical model; it has been used to measure the thickness of both transparent and opaque thin films with high spatial resolution. Thickness sensitivities of +2% over the 500-25,000-A range have been obtained for Al and SiO 2 films on Si substrates.

A new method, based on thermal wave technology, is used to monitor the ion implantation process in silicon. It is a noncontact, nondestructive technique that requires no special sample preparation or processing, has high sensitivity even at low dose, and provides a one-micron spatial resolution capability. This method allows, for the first time, the ability to monitor the critical ion implantation process directly on the patterned product integrated circuit wafers as well as on the usual test wafers.

We describe a new technique for measuring the thickness and optical constants of dielectric, semiconducting, and thin metal films. Beam profile reflectometry provides excellent precision for films as thin as 30 Å and as thick as 20 000 Å. The technique is also capable of simultaneous 2 and 3 parameter measurements and it performs all measurements with a submicron spot size.

Beam-profile reflectometry is a new technique for measuring the thickness and optical constants of dielectric, semiconducting, and thin metal films. The technique consists of measuring the intensity profile of a highly focused beam reflected from the sample. By using a linearly polarized light source and a tightly focussed beam, the S-and P-polarization reflectivities of the film are simultaneously obtained over a wide range of angles. The focusing also provides a submicrometer spot, thus allowing these measurements to be performed in very small geometries. How the information present in the reflectivity profiles can reveal information about as many as three unknown film parameters simultaneously is described, and results from film samples for which the multiparameter fitting capability was essential to the success of the measurement are also presented.