In this work, we optimize a CH₃F/O₂/He/SiCl₄ chemistry to etch silicon nitride gate spacers for 3D CMOS devices in a 300 mm inductively coupled plasma reactor. The chemistry has high directivity and high selectivity to Si and SiO₂. A cyclic approach, which alternates this chemistry with a CH₂F₂/O₂/CH₄/He plasma, is investigated. Using quasi in situ x-ray photoelectron spectroscopy and ellipsometry measurements, etching mechanisms are proposed to explain the results obtained. As a result of process optimization, silicon nitride spacers with vertical profile and a small critical dimension loss of 3 nm as well as complete spacers removal on sidewalls of the active area are obtained on 3D patterns, confirming the advantages of this approach.

中文翻译：

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使用3D CMOS器件的循环方法刻蚀Si3N4的栅极隔离层

在这项工作中，我们优化了CH ₃ F / O ₂ / He / SiCl _4的化学性质，以在300 mm电感耦合等离子体反应器中蚀刻3D CMOS器件的氮化硅栅隔离层。该化学物质对Si和SiO ₂具有高的方向性和高的选择性。研究了一种循环方法，该方法将这种化学反应与CH ₂ F ₂ / O ₂ / CH ₄ / He等离子体交替出现。利用原位准X射线光电子能谱和椭圆光度法测量，蚀刻机制被提出来解释所获得的结果。作为过程优化的结果，在3D图案上获得了具有垂直轮廓和3nm的小临界尺寸损失以及在有源区域的侧壁上完全去除了隔离层的氮化硅隔离层，从而证实了该方法的优势。