Effect of high-frequency variation on the etch characteristics of ArF photoresist and silicon nitride layers in dual frequency superimposed capacitively coupled plasma

Abstract

In this work, the deformation of ArF photoresist (PR) and etch characteristics of the ArF PR and Si3N4 layers were investigated in the dual frequency superimposed capacitively coupled plasmas under different frequency combinations by varying the process parameters such as dc self-bias voltage (Vdc), CF4∕CHF3 flow ratio, and O2 flow rate in the CF4∕CHF3∕O2∕Ar chemistry. Surface roughness measurements and morphological investigation of the line and space patterns after etching by atomic force microscopy and scanning electron microscopy, respectively, showed increased surface roughness and deformation with increasing the Vdc, the high-frequency source frequency (fHF), the CHF3 flow percentage, and the O2 flow rate. The etch rates of the ArF PR and silicon nitride layers were also increased significantly with the Vdc and fHF increased. The Si3N4∕PR etch selectivity was increased most significantly by an increase in the CHF3 flow percentage.