Enhancement of raman scattering intensity of thin film contaminants on substrates

摘要

In the present invention the enhanced Raman spectra of a substance is obtained by depositing a metallic layer upon the surface of the substance. The Raman spectrographic laser is directed to and through the metallic layer, and the Raman scattered energy passes back through the metallic layer and is analyzed by the spectrographic detector. The metallic layer is therefore thin enough to permit passage of the laser energy and scattered energy without significant attenuation. In a preferred embodiment, the spectrographic laser is an argon ion laser and the metallic layer is composed of silver with a thickness of from approximately 1 nm to approximately 20 nm. The present invention is particularly adapted for the analysis of thin film smears deposed upon substrates, such as hard disks. In this application a smear having a thickness of approximately several nm to 30 nm is analyzed by depositing a metallic layer on the smear having a thickness of from approximately 1 nm to approximately 20 nm, and preferably approximately 1 to 8 nm. The preferred metallic layer deposition method is to deposit the metal in a plurality of islands having a diameter from approximately 50 &mgr;m to approximately 60 &mgr;m. The enhanced Raman spectrographic method of the present invention is thus suitable for identifying contaminating smears on the surface of substrates, as well as providing spectrographic information regarding substrate surfaces upon which the thin film metallic layer is deposited.