Low-pressure nonequilibrium plasma for a top-down nanoprocess

The plasma microprocess has developed in cooperation with the miniaturization and high integration of devices in semiconductor manufacturing into a top-down nanoprocess over the last decade. In this paper we present or partly review our series of investigations on a two-frequency capacitively coupled radio frequency plasma (2f-CCP) for etching, sustained by a very-high-frequency source and biased by a low-frequency source in a collisional region. In particular, the velocity distributions of electrons in a bulk plasma, and ions incident on a structured wafer surface are discussed. The plasma surface process, being competitive with etching, deposition, and sometimes charging, has two critical phenomena in etching: plasma molding at a larger structure and microloading at a smaller size. It will be demonstrated that the modeling will be capable of predicting or designing a low-pressure plasma process for etching, after the modeling of the nonequilibrium plasma structure is smoothly coupled with the modeling of the feature profile evolution. Examples of the feature profile evolution of Si, SiO₂ and organic low-k material by using a 2f-CCP in each of the feed gases are shown.