HWAHAK KONGHAK, Vol.29, No.5, 614-621, October, 1991
저압화학증착공정에서 미세선폭 도랑내의 박박 형성에 대한 전산모사
Simulation of Film Growth in Narrow Deep Trench Low Pressure CVD
초록
저압화학증착에 의해 좁고 깊은 도랑내에 증착되는 박막의 층덮힘 특성을 모델링 및 전산모사를 통하여 관찰하였다. 반응물의 표면충돌빈도수가 박막의 성장속도를 결정한다고 가정한 가시각 모델과 반응물이 Knudsen 확산기구에 의해 도랑내로 확산되어 들어간다고 가정한 Knudsen 확산 모델을 기초모델로 하여 전산모사를 수행하였으며, 실제의 증착공정을 모사하기 위해 위의 두 모델을 적절히 배합한 모델로도 전산모사하였다. 이 모델들을 바닥은 실리콘이고 벽면은 산화규소은 가늘고 긴 원통형도랑내에서 텅스텐의 화학증착이 일어나는 경우에 대해 적용하여 다음의 결과를 얻었다. 층덮힘은 도랑이 좁고 깊을수록 나빠지며, 이를 개선하기 위해선 H2/WF6의 비를 낮추거나 온도와 압력을 높여야 한다. 또한, 도랑의 벽면에 약간의 경사를 주는 기하학적 구조를 변화시키는 방법으로도 층덮힘을 크게 개선시킬 수 있다.
A few basic models have been suggested to smiulate the film growth contour in narrow deep trench by low pressure chemical vaoir deposition(LPCVD). Among them, the arrival-angle model assumes that the film growth rate depends on the collision frequency of reactant molecules with the substrate surface, and Knudsen-diffusion model assumes that the reactant diffuse into the trench volume by the Knudsen-diffu-sion mechanism. A third model combines the algorithm of the above two models in the computation process. For demonstration, these models have been applied for simulation of tungsten film deposition and the follow-ing results are obtained. The step coverage is poor when the aspect ratio of trench increases, but is improved when the H2/WF6 ratio decreases and the process temperature and pressure increase. The step coverage by tungsten film is improved when the trench is slightly tapered on both sides.
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