Nano-Pattern Recognition and Correlation Technique for Sub-Nanometer In-Plane Displacement Measurement

An experimental technique to measure sub-nanometer scale in-plane deformations on a micron scale region of interest is proposed. The proposed Nano-Pattern Recognition and Correlation Technique (N-PRCT) utilizes regularly oriented patterns. Displacements are obtained by tracking the movement of each pattern on the images before and after loading through pattern recognition and correlation. The regularity offers a special benefit, relative to the random markings used in the existing techniques, which makes the proposed technique less sensitive to the random noise inherent in digital images at extreme magnifications (a region of interest less than 10 µm). The method is implemented to document thermally-induced deformations of a microelectronics circuit. E-beam lithography is implemented using a standard SEM to fabricate regularly oriented patterns required for N-PRCT. The patterns are produced on a polished cross-section of a flip-chip package, and the package is subsequently subjected to a temperature excursion inside the SEM chamber. Thermal deformations are obtained in a region of interest of approximately 7 × 6 µm.