C. Schmidt, C. Große, F. Altmann, Fraunhofer Institute for Mechanics of Materials, Halle, Germany; J. Schulz, Melexis GmbH, Erfurt, Germany

Summary: Ongoing miniaturization in combination with increased integration density, number of metal layers and functionality are facing more and more the limitations of front side failure localization methods, like emission microscopy, OBIRCH and Lock-in-Thermography (LIT). Furthermore image resolution has to be improved for deep sub micron technologies by application of solid immersion lenses (SIL). First approaches for backside SIL application for emission microscopy could be shown by [1,2] Lock-in Thermography (LIT) can be applied easily for thermal imaging from the IC backside, because silicon is transparent to the used IR-light with about 5µm wavelength. It could be shown that IC structures can be imaged through Si thicknesses of more than 500µm without any preparation steps. By application of SIL, resolution of thermal imaging can be significantly improved up to 1.1 µm. The application of SIL enhanced LIT for front side failure analysis was already demonstrated [3]. In addition to that we have developed an easy-to-use backside SIL approach for LIT using a resently developed SIL holding system. We could show that one and the same SIL can be applied for residual silicon thicknesses in a range from 0-200 µm also from the backside of the chip. The resulting changes in magnification and sensitivity related to the bulk silicon thickness are investigated.