Electron-Beam Induced Resistance CHange (EBIRCH) is a technique that makes use of the electron beam of a scanning electron microscope for defect localization. The beam has an effect on the sample, and the resistance changes resulting from that effect are mapped in the system. This paper explores the beam-based nature of the technique and uses understanding from another beam-based technique, Optical Beam Induced Resistance CHange (OBIRCH), to propose a dominant mechanism. This mechanism may explain the widely different success rates between different types of samples observed after six month’s use of the technique for isolations on large health of line structures in a failure analysis lab.

The timely and accurate imaging of problems in p/n junctions is increasingly important. Scanning Capacitance Microscopy is a current standard for precise 2D-mapping of carrier profiles, but care must be taken to choose the correct field of view because of the slow scan time. This paper provides commentary on the usefulness and possible pitfalls of a wide range of techniques available to the modern FA analyst, with examples from problem solving in a process development environment. SEM passive voltage contrast may provide imaging of junctions, but may be limited to N-well / P-well after special sample prep. OBIRCH provides reliable information on any current flows, but may not be selective specifically to those involving junction problems. Electron Beam Induced Current provides junction information at SEM resolution, but it may be hard for subtle problems to not be swamped out by massive signals. Multi-photon OBIC shows promise for high-resolution laser-based imaging, but may require highly special wiring. Photon Emission is an old standby. A case study is given which shows that one must be careful to match camera type and defect mechanism type in order to be able to see actual junction leakage.

Semiconductor Test Site structures were analyzed using an EBIRCH (Electron Beam Induced Resistance CHange) system. Localization of a RX (active area) to PC (gate) short was achieved with resolution that surpassed that of OBIRCH (Optical Beam Induced Resistance CHange). A voltage breakdown test structure at Metal 1 was stressed in the system, giving isolation to the specific contact. A five-fin diode macro was examined, and it is believed that the electrically active diffusions were imaged as individual fins from Metal 1. A series of ring oscillator devices were examined in steady state condition, and careful consideration of the image supports a hypothesis that Seebeck effect, from heating material interfaces in an EBIRCH system, is the reason for the “dipoles” reported in earlier literature.

The ring oscillator is an important tool for inline monitoring during technology development, as it contains the most important front end of line technology features, is testable at first metal, and generally shows a good correlation to SRAM yield. This work explores various failure analysis techniques for the ring oscillator, during the development of 14 nm FinFET technology. OBIRCH, which is typically a DC technique, was operated with voltages as low as 0.15 V to find multiple defect mechanisms affecting the yield of ring oscillators, which operate at a frequencies in the GHz range. In contrast to typical photon emission analysis of ring oscillators, examines the devices which are flipping on, it is here proposed that the OBIRCH spots which are generated are indications of the Ioff, or the leakage of devices in the inverter stages across the ring. The results from this failure analysis approach enabled a rapid improvement in yield not only of the ring oscillator itself but of the SRAM.