Innovative Measurement Technology for the Semiconductor Device Industry: The Acoustic Microscope - A New Instrument for Viewing Integrated Circuits

摘要

Developments in acoustic microscopy are reported. The operating frequency of scanning acoustic microscopes has been increased from 350 MHz to above 2 GHz, with a resulting improvement in resolution approximating that of the best optical microscopy. An instrument operating in the reflection mode was developed and its design and construction technology were transferred to a group working at the Hughes Research Laboratories on a related program. The utility of the instrument for examination of integrated circuits was demonstrated. The mechanisms by which contrast is produced in the acoustic microscope have been explained theoretically and verified experimentally. The theory has been used to understand the details of the 'signature' response of the instrument as the distance from the lens to the specimen is varied. These responses differ markedly for different specimen materials and for layered structures of varying layer thickness, and may have considerable value for materials analysis studies.