Novel inspection technology for detecting via open using parallel e-beam scanning and graphic design system

Developing a viable in-line monitoring to detect via open defects in the back end of line (BEOL) has been challenging due to the complexity of multiple via structures connected to the metal line. Early in-line detection of these via open defects prior to the electrical die test is crucial for yield improvement. In this paper, we demonstrate a novel inspection technology to detect the critical BEOL via open defects and to separate the signals from the upper and lower metal interconnect layers using parallel e-beam scanning and the graphic design system. Parallel e-beam scanning is an inspection technique that can detect more electrons by adjusting the dwell time of electrons depending on the shape of the metal line pattern, which is controlled by landing energy and the scan direction of the electron beam. In addition, detecting locations of via open were restricted to a single via layout using a die to database inspection system to improve detectability, which is a technique utilized in the semiconductor manufacturing process that involves comparing a specific chip (die) against a reference database to detect defects. Herein, we show that this method can effectively capture the signals of via open defects compared to the conventional e-beam inspection in the complex high dense metal/via structures.