A failure incurred in the front-end is typically a bottleneck to production due the need for physical failure analysis (PFA). Often the challenge is to perform timely localization of the front-end defect, or finding the exact physical defect for process improvement. Many process parameters affect the device behaviour and cause the front-end defect. Simply, the failures are of two types: high-resistance and leakage. A leakage mode defect is the most difficult to inspect. Although conductive atomic force microscopy and six probes nano-probing are popular tools for front-end failure inspection, some specific defects still need more effort. The electrical phenomenon and analysis of a crystalline defect will be demonstrated in this paper. The details will be discussed below.

Focused ion beam (FIB) is a popular tool for physical failure analysis (FA), especially for circuit repair. FIB is especially useful on advanced technology where the FIB is used to modify the circuit for new layout verification or electrical measurement. The samples are prepared till inter-metal dielectric (IMD), then a hole is dug or a metal is deposited or oxide is deposited by FIB. A common assumption is made that metal under oxide can not be seen by FIB. But a metal ion image is desired for further action. Dual beam, FIB and Scanning Electron Microscope (SEM), tools have a special advantage. When switching back and forth from SEM to FIB the observation has been made that the metal lines can be imaged. The details of this technique will be discussed below.

Emission microscopy have been used for failure analysis (FA) defect isolation. But for advanced products, the working voltage of chip is getting smaller, thus many emission spots from normal transistors will be observed, which indeed affects the judgment on the emission spots from killer defects and increases the FA difficulty. Laser scanning microscope (LSM)-based techniques have been powerful defect isolation methods for many years. In this study, Checkpoint Infrascan 200TD, a laser-based tool, is used to perform defect localization. Here, thermally induced voltage alteration and optical beam induced resistance change are used to get defect locations. The study demonstrates three FA cases with 80nm/90nm technologies; metal direct short, poly leakage, and contact high resistance are also found in these cases. It is concluded that, by the selection of control parameters, Infrascan 200TD provides several capabilities of failure site localization and can be applied to different failure modes.