Process Control of Chrome Dry Etching by Complete Characterizationof the RF Power Delivery

摘要

In order to fulfil the upcoming requirements for photomasks there is a need for improving the process stability(reproducibility) of the unit processes in photomask fabrication. In order to understand and minimize the etchcontribution to the CD stability impedance sensors integrated into the capacitively coupled radio frequency (RF) circuit(bias circuit) have shown a big potential''. The last step towards a full characterization of the RF properties is the integration of impedance sensors in theinductively coupled RF circuit (source). This kind of sensor measures voltage, current and phase angle for thefundamental (13.56 MHz) and higher harmonics (up to the 5~(th)harmonic). In this paper we are describing the integration of the Z-Scan sensors into the source RF matchbox and its impact on theRF and CD characteristics of the mask etcher. The central point is the correlation of impedance data to CD data. We willalso compare the responses for bias and source impedance measurements.