Analysis of data pad open failure

We have investigated pad open failure of data line. To verify the mechanism of DPO failure, we designed the new method included in CCD camera and driving circuit and successfully achieved the failure images. The DPO procedure was divided into three steps. First, side wall of Cu film was exposed to Cl plasma and then CuClx compounds formed on surface of Cu film. Subsequently, when it was rinsed by DI water, CuClx was decomposed into Cu and HCl. As a result, etch taper was changed to be abnormal because of re-etching of Cu surface due to HCl. Second, passivation layer was deposited on the data line with poor step coverage. Finally, the panel with poor step coverage was introduced to cleaning bath before module processing and residual water still remained on the data pad area by final operating inspection. Under these conditions, when the operating voltage was applied to the panel, migration of Cu was easily occurred. As a result, we successfully verified the mechanism of DPO in real time.