Abstract The dependence of substrate temperatures (50 to −20 °C) on etch rate in two kinds of PECVD SiN films were investigated by a CF4/H2 mixture plasma. The XRR and XPS results indicate that the chemical composition and film density were almost identical for the films. The FTIR shows that the ratio of N H and Si H groups were found to be significantly different in the SiN films. The N H rich films exhibited a lower etch rate at −20 °C than that observed at room temperature or higher, whereas the Si H rich films showed a higher etch rate at −20 °C. We found that the fluorocarbon thickness was thicker in the Si H rich samples than N H rich samples. The fact suggests that hydrogen originated from the broken Si H bonds enhanced the polymerization, which causes the decrease of etch rate. A thinner fluorocarbon thickness was found in the Si H rich samples at low temperature, which results in the higher etch rate. Angular-resolved XPS indicates that N H bonding formed easier on film surface at −20 °C. These results indicate that the bonding structure and substrate temperature affected the fluorocarbon thickness, fluorine reaction probability and hydrogen dissociation during the SiN etching.

中文翻译：

---

衬底温度对 CF4/H2 等离子体 PECVD-SiN 薄膜刻蚀速率的影响

摘要 通过CF4/H2 混合等离子体研究了两种PECVD SiN 薄膜中衬底温度（50 至-20 °C）对蚀刻速率的依赖性。XRR 和 XPS 结果表明薄膜的化学成分和薄膜密度几乎相同。FTIR 表明，NH 和 Si H 基团的比例在 SiN 薄膜中存在显着差异。富含 NH 的薄膜在 -20 °C 下的蚀刻速率低于在室温或更高温度下观察到的蚀刻速率，而富含 Si H 的薄膜在 -20 °C 时显示出更高的蚀刻速率。我们发现富含 Si H 的样品中的碳氟化合物厚度比富含 NH 的样品更厚。事实表明，来自断裂的 Si H 键的氢增强了聚合，从而导致蚀刻速率下降。在低温下，在富含 Si H 的样品中发现更薄的碳氟化合物厚度，这导致更高的蚀刻速率。角分辨 XPS 表明在 -20 °C 时，NH 键更容易在薄膜表面形成。这些结果表明键合结构和衬底温度影响了 SiN 蚀刻过程中的碳氟化合物厚度、氟反应概率和氢解离。