A method for improving the measurement of semiconductor wafers is
disclosed. In the past, the repeatability of measurements was adversely
affected due to the unpredictable growth of a layer of contamination over
the intentionally deposited dielectric layers. Repeatability can be
enhanced by removing this contamination layer prior to measurement. This
contamination layer can be effectively removed in a non-destructive
fashion by subjecting the wafer to a cleaning step. In one embodiment, the
cleaning is performed by exposing the wafer to microwave radiation.
Alternatively, the wafer can be cleaned with a radiant heat source. These
two cleaning modalities can be used alone or in combination with each
other or in combination with other cleaning modalities. The cleaning step
may be carried out in air, an inert atmosphere or a vacuum. Once the
cleaning has been performed, the wafer can be measured using any number of
known optical measurement systems.
