Edge-Controllable Capacitively Coupled Plasma via Segmented Bias Electrodes

Material and field discontinuities at the wafer edge perturb the plasma sheath in capacitively coupled plasmas (CCPs), producing local distortions in plasma density and potential that translate into non-uniform film deposition and etch profiles. Conventional hardware remedies such as focus or edge rings alleviate these effects only partially; ring erosion and imperfect mechanical integration narrow the allowable process window. Here, we present an actively controlled radio-frequency CCP that uses a segmented bias electrode to compensate edge fields in situ. The independently driven, buried electrodes were integrated around the periphery of the bottom electrode via an external power circuit. This approach enables remote, electrical compensation (tuning) of the field and sheath near the wafer edge without altering the relevant parts, improving the process uniformity and parts lifespan. Plasma parameters are monitored in real time by using optical emission spectroscopy; specifically, the line-ratio method and continuum radiation provided electron density and temperature, linking control parameters and plasma response. We believe that this advanced plasma-shaping strategy widens the operating margin, improves edge uniformity, and prolongs component lifetime in CCP-based microelectronics manufacturing.