Effect of slit electrode structure on electron heating and sheath dynamics in capacitively RF discharges

In a capacitively coupled plasma (CCP), hollow structure showerheads are commonly used for the control of uniform gas distribution. In this study, we investigate the effect of a slit electrode structure on electron heating and transport in a CCP using a two-dimensional particle-in-cell simulation. As the streamlines of the electric fields near the slit structure are alternated, not only the sheath size but also the particle transport become asymmetric between the powered and the ground electrode. The conventional discharges with asymmetric electrode sizes show that sheath expansion and a negative DC bias occur in front of a smaller electrode. With the slit structure, however, it is possible to control the sheath size as well as the DC self-bias by varying the number of slits and the configuration. Furthermore, it is also possible to control the radial plasma uniformity.