Characterization of highly selective SiO2/Si3N4 etching of high-aspect-ratio holes
Characterization of highly selective SiO2/Si3N4 etching of high-aspect-ratio holes
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DOI：
10.1143/jjap.35.2488
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发表时间：
1996-04-01
期刊：
影响因子：
--
通讯作者：
Sekine, M
中科院分区：
文献类型：
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作者：
Hayashi, H;Kurihara, K;Sekine, M
研究了C4F8 + CO等离子体中SiO2和Si3N4接触孔蚀刻速率（RIE-lag）与图案尺寸的关系。发现这些蚀刻速率可以用纵横比来表征，而与图案尺寸无关。SiO2腐蚀速率随长径比的增大而减小，在长径比为6时变为0。Si3N4腐蚀速率也有所下降；然而，蚀刻仍然发生在宽高比为30。通过毛细管板（CPs）的离子电流测量，推断出离子电流的减小会导致腐蚀速率的降低。XPS分析显示，沉积在孔底部的氮化硅表面上的氟碳膜比沉积在平坦的氮化硅表面上的氟碳膜更富f。这解释了为什么即使在高纵横比的孔中也可以蚀刻氮化硅。在C4F8 + CO等离子体中加入少量O-2可解决rie滞后问题。结果表明，随着O-2的加入，高长径比下的离子电流密度增加，有利于SiO2的刻蚀，抑制RIE-lag。
The pattern size dependence of SiO2 and Si3N4 etch rates of contact holes (RIE-lag) in C4F8 + CO plasma was studied. It was found that these etch rates can be characterized by the aspect ratio, regardless of the pattern size. SiO2 etch rate decreased with increasing aspect ratio and became 0 at an aspect ratio of 6. Si3N4 etch rate also decreased; however, etching still occurred at an aspect ratio of 30. From ion current measurements through capillary plates (CPs), it was deduced that etch rates decreased because of decreasing ion current. XPS analyses revealed that fluorocarbon film deposited on the Si3N4 surface at the bottom of a hole was more F-rich than that deposited on a flat Si3N4 surface. This explained why Si3N4 is etched even in high-aspect-ratio holes. A small amount of O-2 addition to the C4F8 + CO plasma resolved the RIE-lag. It was found that the ion current density at high aspect ratio increased with O-2 addition, which would enhance SiO2 etching and contribute to suppressing RIE-lag.