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针对晶圆边缘非垂直刻蚀剖面问题,对300mm双频容性耦合等离子体刻蚀机晶圆边缘离子平均入射角度的分布特性进行了数值模拟研究。采用流体动力学模型求解等离子体宏观特性,氩气作为工艺气体,以一个射频周期内平均离子通量的矢量方向近似为离子平均入射角度,研究发现:边缘效应导致的晶圆边缘鞘层畸变是引起离子平均入射角度偏斜垂直方向的主要原因;晶圆外伸量与可利用半径近似呈负相关关系,且只会影响晶圆边缘向内约10~15mm区域的离子平均入射角度分布;上接地板半径和喷淋头半径影响范围较大,在晶圆半径超过100mm外均有较大影响;适当增大上接地板半径有利于提高离子平均入射角度的垂直性和增大晶圆的有效利用面积,而喷淋头半径在略小于晶圆半径时较佳。
Aiming at the non-vertical etching profile of the wafer edge, the numerical simulation of the distribution of the average incident angle of the wafer edge in the 300mm dual-frequency capacitively coupled plasma etching machine is carried out. Using the fluid dynamics model to solve the macroscopic characteristics of the plasma, argon gas is used as the process gas, and the average ion flux angle is approximated by the vector direction of the ion flux in a radio frequency cycle. It is found that the edge distortion causes the wafer edge distortion Which leads to the main reason that the average angle of incidence of ions deviates in the vertical direction. The amount of wafer extension is approximately inversely related to the available radius, and it only affects the average angle of incidence of ions in the region of about 10-15 mm inward of the wafer edge. The influence of the radius of the ground plate and the radius of the shower head is large, which has a great influence on the wafer radius exceeding 100 mm. Properly increasing the radius of the upper ground plate is beneficial to increase the verticality of the average angle of the ions and increase the effective wafer Utilization area, and the showerhead radius is slightly less than the wafer radius is better.