点击次数：

论文类型：期刊论文

发表时间：2011-02-01

发表刊物：PLASMA SCIENCE & TECHNOLOGY

收录刊物：Scopus、SCIE、EI

卷号：13

期号：1

页面范围：50-54

ISSN号：1009-0630

关键字：plasma sheath; fluid model; RF; circular trench

摘要：Since processed substrates usually exhibit nonplanar surface structures in micro-electro-mechanical-systems (MEMS) etching, a two-dimensional (2D) fluid model is developed to simulate the characteristics of the sheath near a conductive substrate with a circular trench, which is placed in an argon discharge powered by a radio-frequency (RF) current source. The model consists of 2D time-dependent fluid equations, the Poisson equation, and a current balance equation that can self-consistently determine the instantaneous voltage on the substrate placed on a powered electrode. The erects of both the aspect ratio (depth/width) and the structure of the trench on the characteristics of the sheath are simulated. The time-averaged potential and electric field in the sheath are calculated and compared for different discharge parameters. The results show that the radial sheath profile is not uniform and always tends to adapt to the contour of the substrate, which is believed to be the moulding effect. Affected by the structure of the substrate surface, the potential and electric field near the inner and outer side walls of the trench exhibit obvious non-uniformity, which will inevitably lead to non-uniformity in etching, such as notching. Furthermore, with a fixed amplitude of the RF current source, the potential drops and the sheath thickness decrease with an increase in aspect ratio.