Photo Emission Microscopy
Photo emission microscopy or light emission microscopy e.g., Hot Spot Inspection is an advance failure analysis technique for detecting photonic radiation from a defective site due to excessive heat generated at the defective site. The emission light are not visible to the naked eye. Photo emission microscopy uses powerful imaging equipment to intensify low emitted lights that can be visible through a CCD camera. The emitted light location coincides with the precise location of the defect on the die surface image. The following are two different techniques used in this analysis:
EMMI (Emission Microscopy)
EMMI is non-invasive and can be performed from either the back or front of the specimen. The sample is electrically powered and compared to a known good device under the emission microscope. Emitted photons are detected by highly-sensitive CCD camera. EMMI is capable of detecting light wavelength between 350 nm ~ 1100 nm. MMI is used for detecting leakage current resulting from device defects, e.g., Gate oxide defects / Leakage, Latch Up, ESD Failure, junction Leakage, etc.
InGaAs EMMI (Indium Gallium Arsenide Emission Microscopy)
InGaAs EMMI is similar to EMMI technique. However, InGaAs EMMI uses InAgAs detectors for detection of emitted photons at the defect site. This technique shifts the detection of InGaAs to a longer wavelength range, between 900 and 1700 nm (infrared). InGaAs EMMI is 5 to 10 times faster and is more sensitive than EMMI.
OBRICH (Optical Beam Induced Resistance Change)
A laser beam is used to induce a thermal change in the device-under-test (DUT). Thermal characteristics between defect and non-defect sites are stimulated by the laser. A metal line carrying a current heats by the laser, resulting an impedance change that is detected by monitoring the input current to the DUT. OBIRCH is useful for detecting electromigration effects resulting in open metal lines.