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Home > Other Testing Service > Failure Analysis Experiments > OBRIRCH Fault Detection
OBRIRCH Fault Detection
OBIRCH Principle:

When a laser beam, finely focused by an objective lens, irradiates a sample surface, various kinds of signals are emitted as result of interaction between the incident laser beam and the sample. Visualization of these phenomena can be made by detecting these various photo effects caused by the interaction and by displaying them on a vewing screen synchronized with the scanning of the laser beam.

When the laser beam with energy higher than the band gap energy of the pn junction irradiates semiconductor devices, electron-hall pairs are generated and they flow in the semiconductor to make electron current. Detecting this current and displaying on a viewing screen, we obtain OBIC image, and they are used for failure analysis of semiconductor devices. Applying a bias voltage to the wire in the wiring area of semiconductor, we can detect a current change due to the resistance change by scanning the focused laser beam over the surface. This is the Optical Beam Induced Resistance Change (OBIRCH).

     Optical Beam Induced Resistance Change (OBIRCH) is mainly achieved by using the laser beam to scan the device surface while some of the laser energy converted into heat. If some defects / holes existed in the interconnecting wire where the heat conduction nearby is different with the intact one, there will be local temperature changes caused, which will correspondingly cause resistance to change ΔR. If constant voltage is imposed to the interconnecting wires, there will be a current change relationship expressed by formula ΔI=(ΔR/V)I2, which links the resistance changes & current changes caused by heat together. Based on the principle that the image pixel brightness is the reflection corresponding to current changes while the pixel location corresponding to the laser scanned location for current changes, the defect locations can be detected through OBIRCH this way.

        OBIRCH is commonly applied to the chip internal high impedance & low impedance analysis, circuit leakage path analysis etc. It's not only an effective way to locate the defects in the circuits such as holes in the wire, holes under through-hole & high impedance area of through-hole bottom etc, but also a powerful supplement of  light microscopy technologies for effective short-circuit & leakage checking.

Obirch leakage path analysis