Solid Immersion Microscopy

The Solid Immersion Microscope (SIM) is a new type of optical microscope that is built as an add-on to an existing microscope. By adding a single glass element, the "Solid Immersion Lens," to a standard or confocal optical microscope, transverse resolution improvements by a factor of two or more can be achieved. The SIM can be operated as a real-time near-field optical microscope and has demonstrated a transverse resolution of less than 100 nm using visible light. It can also be used to image inside transparent materials without aberration and with a numerical aperture (N.A.) of greater than 1. In this dissertation, the general principles of the solid immersion microscope and the experimental apparatus in our laboratory will be described. The theory for the microscope's transverse and depth responses will then be studied in more detail and experimental results will be shown to support this theory. The theoretical development will be general enough to predict the resolution of standard confocal microscopes, and to include the effects of thin transparent films on the object and aberrations in the optics. The theory will also show the effects of the air gap between the SIL and the object. The dissertation will conclude with a discussion of the potential applications of solid immersion techniques. These applications include semiconductor inspection and photolithography, in both cases using an N.A. of 1.6 or higher and with no need to immerse the sample in oil. The SIM could also be used in biology, and we have proposed a method to achieve an N.A. of 2.1, that would allow structures down to about 50 nm in size to be observed in their native environments. Finally, the SIM could also be used to inspect optical disks through the substrate with an N.A. of 1.2. These techniques could be used to make an optical head with an N.A. of 1.5 times the presently used heads and better tolerance to aberrations. This could result in an increase in storage density by more than a factor of 2.