Balancing the etching and passivation in time-multiplexed deep dry etching of silicon
Balancing the etching and passivation in time-multiplexed deep dry etching of silicon
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DOI：
10.1116/1.1415511
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发表时间：
2001-11-01
影响因子：
1.4
通讯作者：
van der Drift, E
中科院分区：
文献类型：
--
作者：
Blaw, MA;Zijlstra, T;van der Drift, E
针对采用SF6-C4F8的博世深硅干法刻蚀工艺，提出了一种定量方法。揭示了高深宽比结构中等离子体表面的基本相互作用以及离子和自由基的输运性质。平衡蚀刻和钝化脉冲期间的相互作用对于最大限度地控制轮廓至关重要。在各向异性区域，刻蚀速率主要取决于长宽比，这主要是由于氟自由基的耗尽，以及一定程度的钝化聚合物再沉积。由于沟槽底部聚合物钝化的去除不当，各向异性过程往往在极限长宽比处停止。更高的离子通量和离子能量被发现是推动博世工艺达到更高可实现长径比的关键。讨论了实际过程中的影响。原位椭圆偏振测量表明，聚合物钝化过程是一个含有离子诱导组分的复杂过程。通过调整等离子体化学成分来更有效地去除沟槽底部的钝化层，可以进一步改善博世等离子体刻蚀工艺。(C)2001年美国真空协会。
For the Bosch deep silicon dry etch process with SF6-C4F8 a quantitative approach is developed. Essential plasma surface interactions and the transport properties of ions and radicals in high aspect ratio structures are unravelled. Balancing the interactions during etching and passivation pulses is essential for maximal profile control. In the anisotropic regime the etch rate is aspect ratio dependent largely due to depletion of fluorine radicals and with some involvement of passivation polymer redeposition. The anisotropic process tends to stop at a limiting aspect ratio because of improper removal of polymer passivation at the trench bottom. Both higher ion flux and ion energy are found to be crucial to push the Bosch process to higher achievable aspect ratios. Practical process implications are discussed. In situ ellipsometry shows that the polymer passivation step is a complex process with an ion induced component. More efficient removal of the passivation layer at the trench bottom by adjusting the plasma chemistry could further improve the Bosch plasma etch process. (C) 2001 American Vacuum Society.