Impacts of inorganic fluoride on plasma etching process

The plasma resistant materials, such as yttrium oxide (Y
₂
O
₃
), are synthesized as a coating to protect the surface of the key components, such as showerhead (SH), for the plasma etching chamber. When the F contained plasma is used in the etching process, the inorganic fluoride, such as YF
₃
deposition, is usually formed over Y
₂
O
₃
coating on the SH surface and may induce the particle while the thickness of the deposition is increased along the process time. The present work identified the structural features of inorganic fluoride depositions with the correlation of the plasma etching processes. It was found that the dense inorganic fluoride with the good adhesion on Y
₂
O
₃
coating may not induce the particle in the etching process. However, some geometric features on SH could help to accumulate the inorganic fluoride deposition, which leads to the local crack and peeling of the deposition, and induce the particle contamination into the process. It has been concluded that the control and reduction of the particle can be reached by the modification of the SH design and the wet cleaning process, which helps to stabilize the plasma etching process and increases the lifetime of Y
₂
O
₃
coated SH.