Influence of the RF-power on the etching yields and surface morphology in reactive ion beam etching of Si and photoresist

The change in ion energy distribution and composition of a reactive ion beam produced by an RF-excited ion beam source and operation with a mixture of CHF3 and O2 was investigated and correlated with the etching behavior. To this end, measurements were performed with an energy-selective mass spectrometer to determine ion energy distributions, current density measurements for the measurement of current density distributions of the ion beam, and tactile measurements to determine the etching rates of Si and photoresist. The morphology of the photoresist was measured with a scanning force microscope. In particular, alterations in the etching yield and surface morphology of the photoresist can be observed in response to changes in the applied RF-power. An increase in plasma density leads to an increase in fragmentation processes of the injected reactive gases, resulting in the formation of smaller fragments. These smaller fragments have a chemical impact on the substrate surface, which affects the etching performance. These effects can have significant consequences in the context of long-time reactive ion beam processing for patterning applications.