Ion velocity distributions in helicon wave plasmas: Magnetic field and pressure effects
Ion velocity distributions in helicon wave plasmas: Magnetic field and pressure effects
复制标题
螺旋波等离子体中的离子速度分布：磁场和压力效应
DOI：
10.1116/1.586541
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发表时间：
1993
影响因子：
1.4
通讯作者：
N. Sadeghi
中科院分区：
文献类型：
--
作者：
T. Nakano;K. Giapis;R. Gottscho;T. C. Lee;N. Sadeghi
考虑高密度、低压等离子体系统中的离子传输对于满足超大规模集成电路制造的工艺要求非常重要。等离子体和晶片之间的边界处的离子能量和角度分布、鞘层影响蚀刻选择性、线宽控制、等离子体引起的损伤和微观蚀刻均匀性。反过来，这些分布很容易通过改变磁场分布和/或中性气体压力来改变。使用多普勒频移激光诱导荧光，测量了螺旋波激发的 Ar 等离子体中的亚稳态离子速度分布函数。研究了两种磁场配置。对于磁“镜”，其中场在源中表现出最大值和鞍点，观察到等离子体是不对称和不均匀的：这导致速度分布变宽以及从等离子体的一个区域到另一个区域的显着离子漂移。当镜场配置中的压力增加时，横向离子“温度”呈现出作为压力的函数的最大值，并且当蚀刻受到离子通量限制时，减少或增加压力将导致改进的线宽控制。当磁场在源中反转并在下游再次反转时，等离子体更加对称。通过这种双尖点配置，横向离子温度随压力单调降低，并且通过在较高压力下操作将获得离子通量限制中改进的线宽控制。
Consideration of ion transport in high density, low pressure plasma systems is important for meeting process requirements in the manufacturing of ultra-large-scale integrated circuits. The ion energy and angular distributions at the boundary between the plasma and the wafer, the sheath, influence etching selectivity, linewidth control, plasma-induced damage, and microscopic etching uniformity. These distributions, in turn, are easily altered by changing the magnetic field profile and/or the neutral gas pressure. Using Doppler-shifted laser-induced fluorescence, metastable ion velocity distribution functions in helicon-wave-excited Ar plasmas are measured. Two magnetic field configurations are examined. For a magnetic "mirror," where the field exhibits a maximum and a saddle point in the source, the plasma is observed to be asymmetric and nonuniform: this leads to broadened velocity distributions and significant ion drift from one region of the plasma to another. As the pressure is increased in the mirror field configuration, the transverse ion "temperature" exhibits a maximum as a function of pressure and, when etching is ion-flux limited, either decreasing or increasing the pressure should result in improved linewidth control. The plasma is more symmetric when the magnetic field is reversed in the source and again downstream. With this double cusp configuration, the transverse ion temperature decreases monotonically with pressure, and improved linewidth control in the ion-flux limit would be obtained by operating at higher pressure.