Aspect ratio dependent etching lag reduction in deep silicon etch processes
Aspect ratio dependent etching lag reduction in deep silicon etch processes
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DOI：
10.1116/1.2172944
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发表时间：
2006-07-01
影响因子：
2.9
通讯作者：
Westerman, R.
中科院分区：
文献类型：
--
作者：
Lai, S. L.;Johnson, D.;Westerman, R.
微机电系统（MEMS）器件制造通常涉及具有高纵横比的三维结构。此外，MEMS设计需要具有不同尺寸和纵横比的结构共存于单个微芯片上。深硅刻蚀工艺中存在深宽比相关刻蚀（ARDE）效应。对于同时蚀刻不同尺寸的特征，ARDE效应导致以更快的速率蚀刻更大的特征。实际上，ARDE效应对MEMS器件制造具有许多不期望的复杂性。本文介绍了一种描述时分复用（TDM）等离子体刻蚀工艺的物理模型，以及减少ARDE滞后的实验结果。该模型将TDM等离子体蚀刻工艺中的单个等离子体蚀刻循环分解为聚合物沉积、聚合物去除和自发硅蚀刻阶段。从模型中获得的见解和钝化和蚀刻步骤的控制，它已被证明，ARDE滞后可以有效地控制。实验表明，正常的ARDE滞后可以改变为逆ARDE滞后。在优化条件下，对于宽度范围从2.5到100 μ m的沟槽，ARDE滞后被减小到低于2%-3%，同时在具有不同尺寸的沟槽中保持良好的蚀刻轮廓。这种结果是在蚀刻速率超过2 μ m/min时实现的。（c）2006年美国真空学会。
Microelectromechanical system (MEMS) device fabrication often involves three dimensional structures with high aspect ratios. Moreover, MEMS designs require structures with different dimensions and aspect ratios to coexist on a single microchip. There is a well-documented aspect ratio dependent etching (ARDE) effect in deep silicon etching processes. For features with different dimensions etched simultaneously, the ARDE effect causes bigger features to be etched at faster rates. In practice, ARDE effect has many undesired complications to MEMS device fabrication. This article presents a physical model to describe the time division multiplex (TDM) plasma etch processes and thereafter the experimental results on ARDE lag reduction. The model breaks individual plasma etch cycles in the TDM plasma etch processes into polymer deposition, polymer removal, and spontaneous silicon etching stages. With the insights gained from the model and control over the passivation and etch steps, it has been demonstrated that ARDE lag can be controlled effectively. Experiments have shown that a normal ARDE lag can be changed to an inverse ARDE lag. Under optimized conditions, the ARDE lag is reduced to below 2%-3% for trenches with widths ranging from 2.5 to 100 mu m, while maintaining good etch profile in trenches with different dimensions. Such results are achieved at etch rates exceeding 2 mu m/min. (c) 2006 American Vacuum Society.