본 연구에서는 플라즈마 화학 기상 증착(PCVD: Plasma Chemical Vapor Deposition)을 이용한 반도체 제조 공정 중에 생성되는 화학종들 및 입자들의 농도 분포를 공정변수 변화에 따라 모델식을 사용하여 고찰하였다. 화학종들에 대한 물질 수지식에는 플라즈마 화학반응, 유체대류, 확산 및 전기적 이동 등의 영향을 고려하였으며, 입자 거동에 대한 모델식에는 유체대류, 입자확산, 외부힘(이온항력, 정전기력, 중력) 등의 영향을 고려하였다. SiH_x⁺ 이온의 농도는 날카로운 최고점을 보이며 두 sheath 영역에서 0에 접근하였다. 두 sheath 영역에서 음이온의 농도는 0에 접근하였고, 대부분의 음이온들은 벌크 플라즈마 영역에 존재하였다. 유체대류의 영향으로 하류 sheath 근처에서의 음이온 농도가 상류 sheath 근처에서보다 높게 나타났다. 대부분의 입자들은 전기적인 반발력과 이온항력이 균형을 이루고 있는 두 sheath 경계 영역에 분포하여 두 sheath 영역과 벌크 플라즈마 영역에서의 입자 농도는 각각 0에 접근하였다. 유체대류의 영향으로 하류 sheath 경계 영역에서의 입자 농도가 상류 sheath 경계 영역에서 보다 높게 나타났다. 입자 크기가 0.1㎛에서 10㎛으로 증가함에 따라 유체대류의 영향에 의해 대부분의 입자들이 하류 sheath 경계 영역에 위치하였다. 양이온과 음이온의 거동은 SiH₄ PCVD에서 이온 항력이 입자 거동에 미치는 영향을 계산하는데 중요하게 작용하였다.

The distributions of chemical species and particles inside a silane plasma chemical vapor deposition (PCVD) reactor were theoretically investigated under various plasma conditions. We included the effects of chemical reactions, fluid convection, diffusion and electrical migration on the governing equations of chemical species. The effects of fluid convection, particle diffusion and external forces (ion drag, electrostatic and gravitational forces) on the movement of particles inside the plasma reactor were also examined. The SiH(x)(+) concentration profiles showed sharp peaks at the reactor center, but almost zero in the sheath regions. The concentrations of negative ions in the sheath region became almost zero and most of them were contained inside the bulk plasma. The concentrations of negative ions at the downstream sheath boundary were higher than those at the upstream sheath boundary due to the effect of fluid convection. Most of those particles were located in the region near the sheath boundaries by the balance between the ion drag and electrostatic forces, but the particle concentrations in the sheath region and in the bulk plasma were almost zero. The particle concentrations were greater at the downstream sheath boundary than at the upstream sheath boundary by the effect of fluid convection. As the particle size increased from 0.1 to 10 μm, most particles were located at the downstream sheath boundary by the effect of fluid convection. It was found that the movements of negative ions as well as the positive ions were also important for determining the ion drag force acting on particles in silane PCVD.

SiH4 PCVD Plasma Chemistry Particle Movement External Forces on Particles

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