Advanced technology for monitoring plasma sparking ESD damage using high frequency magnetic field sensors

In plasma processes, the sparking events inside the chamber of plasma instruments damage the advanced electron devices which are the new products with reduction patterns and are made on large diameter wafers. Recently, the monitoring technologies such as the power source noise, the RF reflected wave and the acoustic emission have begun to be used in order to detect the sparking events. This paper presents an advanced monitoring technology that detects mainly electromagnetic waves, which are emitted by the sparking events. It is characterized in that the technology monitors the high frequency magnetic flux emitted from the aperture (view port) of the chamber. Moreover, the magnetic field sensor that is shielded by a waveguide can differentiate the spark from the peripheral electromagnetic noise, which was a problem of the current monitoring technologies. The magnetic field sensor showed sufficient sensitivity, and the modifications of the chamber and the power circuit were hardly necessary. The sparking events and the operating sequences of the plasma instrument, by which some wafers were etched, were simultaneously plotted in the time series data on a computer display. The results showed that the sparking events damaged the wafers at some operating-timings. In addition, the time series data of the sparking events and the particle number, which was detected by a laser particle counter, were compared on the computer display. The results showed that the sparking had generated many particles that were larger than 80 nm.