Method for assessing the effects of plasma treatments on wafers of semicondutor material

摘要

The method described provides for the following operations: forming cells of EEPROM type on a wafer with source (S), drain (D) and control gate (G) surface terminals (pads), subjecting the cells to UV radiation so as to erase them thereby fixing a reference threshold voltage, applying programming voltages of preset value to one of the cells and measuring the corresponding threshold voltages, subjecting this cell to UV radiation so as to restore its threshold to the reference value, subjecting the wafer to the plasma treatment to be assessed, measuring the threshold voltages of the cells and comparing them with the reference threshold voltage so as to derive from the comparison information on the alterations induced on the dielectrics formed on the wafer and on the distribution of the plasma potential. The method guarantees high sensitivity of measurement, great reliability and reproducibility of the measurements and can be used with advantage both in the design of equipment for plasma treatments and in the fabrication of semiconductor devices in order to increase production yield.