Impedance monitoring of a plasma chamber under plasma-off conditions for contamination control

Abstract Changes in the conditions of a plasma process chamber often cause process shifts during plasma processes. We studied the chamber impedance monitoring under off-plasma conditions. As the deposition process continues, film residues accumulate on the chamber showerhead and components, potentially altering the impedance in the process chamber. When measured by a vector network analyzer (VNA), the reactance component increases significantly in the negative region. Notably, a strong correlation ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow> <mml:mi>R</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> <mml:mo>=</mml:mo> <mml:mn>0.99</mml:mn> </mml:math> ) was observed between the height of the SiF 3 peak, indicative of the contamination level during the in situ dry cleaning (ISD) step. This correlation was attributed to an increase in the capacitance component within the chamber, as verified through equivalent circuit analysis. These results demonstrate the feasibility of monitoring chamber contamination even in the off-plasma state.