Si nanocone structure fabricated by a relatively high-pressure hydrogen plasma in the range of 3.3–27 kPa

Abstract

In this study, we prepared a silicon nanocone structure using a relatively high-pressure H2 plasma in the range of 3.3–27 kPa. The silicon sample with the prepared nanocone structure exhibited a black surface. We investigated the dependence of the silicon nanocone formation behavior on various experimental parameters such as H2 pressure, processing time, substrate temperature, input power, and substrate bias. A small amount of air feed and a thin native oxide layer are desirable for the nanocone formation. Furthermore, the silicon temperature during plasma exposure plays an important role in increasing the silicon nanocone height. In addition, the polarity of the substrate bias drastically changes the surface structure from the nanocone in the case of a negative bias to a low-aspect-ratio pyramidal structure in that of a positive bias. This result implies that the anisotropic ion incidence is important for nanocone formation, despite the relatively high process pressure.