5 June 2001 High-resolution IC inspection technique
Author Affiliations +
Proceedings Volume 4275, Metrology-based Control for Micro-Manufacturing; (2001) https://doi.org/10.1117/12.429355
Event: Photonics West 2001 - LASE, 2001, San Jose, CA, United States
We demonstrate a through the substrate, numerical aperture increasing lens (NAIL) technique for high-resolution inspection of silicon devices. We experimentally demonstrate a resolution of 0.2 micrometers , with the ultimate diffraction limit of 0.14 micrometers . Absorption limits inspection in silicon to wavelengths greater than 1 micrometers , placing an ultimate limit of 0.5 micrometers resolution on standard subsurface microscopy techniques. Our numerical aperture increasing lens reduces this limit to 0.14 micrometers , a significant improvement for device visual inspection (patent pending). The NAIL technique yields a resolution improvement over standard optical microscopy of at least a factor of n, the refractive index of the substrate material, and up to a factor of n 2. In silicon, this constitutes a resolution improvement between 3.6 and 13. This is accomplished by increasing the numerical aperture of the imaging system, without introducing any spherical aberration to the collected light. A specialized lens made of the same material as the substrate is placed on the back surface of the substrate. The convex surface of this lens is spherical with a radius of curvature, R. The vertical thickness of the lens, D, should be selected according to D equals $ (1 + 1/n)-X and the substrate thickness X.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Stephen Bradley Ippolito, Stephen Bradley Ippolito, Anna K. Swan, Anna K. Swan, Bennett B. Goldberg, Bennett B. Goldberg, M. Selim Unlu, M. Selim Unlu, } "High-resolution IC inspection technique", Proc. SPIE 4275, Metrology-based Control for Micro-Manufacturing, (5 June 2001); doi: 10.1117/12.429355; https://doi.org/10.1117/12.429355

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