Dry etching in the presence of physisorption of neutrals at lower temperatures
Dry etching in the presence of physisorption of neutrals at lower temperatures
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DOI：
10.1116/6.0002230
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发表时间：
2023-03-01
影响因子：
2.9
通讯作者：
Vahedi, Vahid
中科院分区：
文献类型：
--
作者：
Lill, Thorsten;Berry, Ivan L. L.;Vahedi, Vahid
在这篇文章中，我们概述了在较低的晶圆温度下蚀刻中起作用的化学和物理过程。传统上，等离子体蚀刻工艺依赖于自由基的形成，自由基容易在表面化学吸附。分子在低温下通过物理吸附进行吸附，但它们缺乏足够的能量来克服化学反应的能量势垒。在半导体制造中使用的典型等离子体中的自由基的密度比中性物的浓度低一到两个数量级。因此，在低温下中性物质的物理吸附有意义地增加了表面上的中性浓度，并且如果它们被化学活化则有助于蚀刻。在高纵横比功能的中性粒子的运输是在低温下增强，因为物理吸附的物种是移动的。低温蚀刻的温度窗口在低端被包括毛细管效应的冷凝和在高端减少的物理吸附包围。有用的温度窗口取决于化学。除了阐明使低温处理独特的基本效应外，本文还说明了其在半导体蚀刻应用中的实用性。
In this article, we give an overview about the chemical and physical processes that play a role in etching at lower wafer temperatures. Conventionally, plasma etching processes rely on the formation of radicals, which readily chemisorb at the surface. Molecules adsorb via physisorption at low temperatures, but they lack enough energy to overcome the energy barrier for a chemical reaction. The density of radicals in a typical plasma used in semiconductor manufacturing is one to two orders of magnitude lower than the concentration of the neutrals. Physisorption of neutrals at low temperatures, therefore, increases the neutral concentration on the surface meaningfully and contributes to etching if they are chemically activated. The transport of neutrals in high aspect ratio features is enhanced at low temperatures because physisorbed species are mobile. The temperature window of low temperature etching is bracketed at the low end by condensation including capillary effects and diminished physisorption at the high end. The useful temperature window is chemistry dependent. Besides illuminating the fundamental effects, which make low temperature processing unique, this article illustrates its utility for semiconductor etching applications.