MSE PhD Prospectus Defense: Abdulkadir Yurt

Boston University Division of Materials Science and Engineering PhD Prospectus Defense Abdulkadir Yurt Advisor: Professor M. Selim Unlu High resolution interferometric microscopy for integrated circuit inspection Abstract: In accordance with the Moore’s law, the semiconductor industry has proceeded to 22nm technology node and is currently devising the process framework for the smaller nodes. The circuit inspection tools that have had a critical role in the rapid advancement of the manufacturing technology have become relatively ineffective due to the new challenges arisen in recent years. Back‐side laser beam probing microscopy is one of the powerful circuit inspection tools to examine the circuit activity in a non‐destructive fashion. In this work, we develop a set of methods to improve the signal sensitivity and signal isolation capability of the back‐side laser beam probing methods to address the challenges associated with the inspection of the circuit activity at 22nm technology node and beyond. In the first part of the proposed research, we design and implement a dual‐phase interferometric method for improving the signal extraction efficiency of the microscope. We demonstrate the effectiveness of the method through presenting two case studies on the inverter chains in chips of 180nm bulk silicon and 32nm silicon‐on‐insulator technologies. The preliminary studies have showed up to an order of magnitude improvement in signal to noise ratio for the circuits operating at relatively low frequency regime (12.5MHz). Future efforts will focus on the implementation of the technique will be extended to the circuits operating at GHz regime. In the second part, we aim to improve spatial resolution of the microscope beyond the classical definition of diffraction limit of light in an imaging system through engineering the spatial amplitude and/or phase properties of the focused radially, circularly and linearly polarized beams. Our preliminary studies show that the radially polarized beam is in particular promising as its circular focal spot can be decreased down to 0.15λ0 in linewidth on the device layer by using annular amplitude filters. For linear and circular polarization illuminations, we will investigate spatial phase masks for realizing optimal focal spot size and morphology. The techniques developed in the first and second part of this study are implemented in the illumination and collection paths of the microscope, respectively. The combination of both techniques in the final phase will present the advantage of high signal detection sensitivity and spatial resolution on the same platform. Committee: Advisor/Committee Chair: CoE Associate Dean and ECE Professor Selim Unlu PHO Director and ME Professor Tom Bifano Physics and ECE Professor Bennett Goldberg ECE Professor Siddharth Ramachandran