Use of ADC/RTC to trace intermittent and rare events causing yield limiting front-end defects in deep sub-micron CMOS processes

The ability to detect yield-limiting defects during processing reduces the number of learning cycles needed to solve problems. Traditional inspection equipment provide a distribution over a wide range of defect types. ADC (Automatic Defect Classification) and RTC (Real Time Classification) on bright field inspection tools help provide insight into the distribution of on-wafer defect types. In our particular case, ADC was used to track the severity of a yield limiting front-end defect on our 0.25 μm process line. Most semiconductor factories will trend random defects or added defects in their SPC system, but few have the capability to trend a specific defect type at an inspection point.