In-line failure analysis on productive wafers with dual-beam SEM/FIB systems

Modern dual beam SEM/FIB tools will allow physical failure analysis on productive wafers in the cleanroom if contamination of wafer and production equipment can be controlled. In this study we show that the risks of Ga- diffusion and -desorption as well as heavy metal contamination can be overcome. The reentry of analyzed wafers into the production flow results in lower overall costs and a dramatically shortened feedback loop to production engineers, leading to reduced down times of production tools etc. Most FIB-applications (i.e. highlight etch of cross sections) can be processed with appropriate gas chemistry. Ion Beam deposition of an insulating material to refill the crater created by the sputtering process is also investigated. If either resolution is not sufficient or more complex analyses have to be applied a sample lift-out technique was developed making it obsolete to sacrifice wafers also in these cases. The fixed sample can be analyzed off-line with all PFA- methods, even plasma etching or lift-off in HF is possible. The benefits of this quantum leap for physical failure analysis are reduction of wafer costs and the possibility to reduce analysis cycle time as well as the number of learning cycles in technology development.