Optical beam induced resistance change (OBIRCH): overview and recent results

The OBIRCH is an indispensable failure analysis tool in the semiconductor industry. It is useful not only for test structures but also for final products. It is useful for field failures and the failures in manufacturing processes at development phase and mass-production phase. The IR-OBIRCH can detect defects and current paths from the backside of Si chips because of small attenuation of 1.3-um-wavelength laser in Si. The sensitivity of defect detection using the OBIRCH has been improved in various ways. the use of a near-field optical probe instead of the laser (NF-OBIRCH) and the use of the combination of laser-modulation and lock-in amplifier made it possible to get a OBIRCH image and a OBIC (optical beam induced current) image with highest spatial resolution of 50 nm. For the future applications of the OBIRCH, two different approaches are promising: specially designed test structures and solid immersion lens.