OBIRCH based on differential imaging locating method

Optical Beam Induced Resistance Change (OBIRCH) is a common method to detect IC resistive/short failure based on the thermal effect stimulated by laser scanning. When the bias voltage is low, OBIRCH may face the problems of weak failure signal, poor quality of OBIRCH image influenced by the noise. To solve these problems and improve the precision of OBIRCH a signal-noise model of OBIRCH is established and a differential image locating algorithm is designed. First, two groups of image with different failure signal strength by adjusting bias voltage are acquired and mean difference image of these two group images is obtained by calculating. Then, mean filter and image binarized are performed and get a statistical image. Failure point can be effectively located according to the statistical image. The accuracy of OBIRCH based on differential imaging locating method has been proved by physical analysis.