Damage effects in Pyrex by CF4 reactive ion etching in dual RF-microwave plasmas

The bonding disruption and thermal damage induced on Pyrex substrates during the reactive ion etching in CF₄/Ar and CF ₄/O₂ dual RF-microwave plasmas is reported. Energy dispersive X-ray and scanning probe analyses indicate that metallic impurities aggregate in clusters of different atomic abundance. These clusters are shown to disrupt the homogeneity and contribute to a non-uniform etching of the substrates. The surface morphology, chemical composition and etching rate are shown to vary with the substrate impedance. Furthermore, the edge effects, local elemental composition, free radical permeation and extended exposure to microwave power are believed to induce substantial thermal damage