A Method for Diagnosing the Process Chamber Prior to Plasma Processes

This paper presents a method to diagnose a process chamber prior to the plasma process. Although a variety of studies on plasma diagnostics have been implemented, they detect the states only during the plasma processes. In addition to the process states, it is essential to diagnose a process chamber itself before the process for proper preparation. For example, abnormal states such as hardware assembly issues and wafer shift should be monitored. The proposed method is based on the broadband $S_{11}$ that is measured through a viewport of the process chamber. Depending on the dimensions of the process chamber, resonance behaviors are observed at specific frequencies. For the multiple resonances, asymmetrical multiple resonance probes (MRP) were investigated through EM simulation. In addition, it was verified that the process chamber can be diagnosed with a similarity algorithm, comparing $S_{11}$ of the abnormal states with that of the normal state in terms of magnitude and phase.