Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
Oxford Instruments Plasma Technology, North End, Bristol BS49 4AP, U.K.
ACS Appl Mater Interfaces. 2017 Jan 18;9(2):1858-1869. doi: 10.1021/acsami.6b12267. Epub 2017 Jan 6.
The advent of three-dimensional (3D) finFET transistors and emergence of novel memory technologies place stringent requirements on the processing of silicon nitride (SiN) films used for a variety of applications in device manufacturing. In many cases, a low temperature (<400 °C) deposition process is desired that yields high quality SiN films that are etch resistant and also conformal when grown on 3D substrate topographies. In this work, we developed a novel plasma-enhanced atomic layer deposition (PEALD) process for SiN using a mono-aminosilane precursor, di(sec-butylamino)silane (DSBAS, SiHN(Bu)), and N plasma. Material properties have been analyzed over a wide stage temperature range (100-500 °C) and compared with those obtained in our previous work for SiN deposited using a bis-aminosilane precursor, bis(tert-butylamino)silane (BTBAS, SiH(NHBu)), and N plasma. Dense films (∼3.1 g/cm) with low C, O, and H contents at low substrate temperatures (<400 °C) were obtained on planar substrates for this process when compared to other processes reported in the literature. The developed process was also used for depositing SiN films on high aspect ratio (4.5:1) 3D trench nanostructures to investigate film conformality and wet-etch resistance (in dilute hydrofluoric acid, HF/HO = 1:100) relevant for state-of-the-art device architectures. Film conformality was below the desired levels of >95% and attributed to the combined role played by nitrogen plasma soft saturation, radical species recombination, and ion directionality during SiN deposition on 3D substrates. Yet, very low wet-etch rates (WER ≤ 2 nm/min) were observed at the top, sidewall, and bottom trench regions of the most conformal film deposited at low substrate temperature (<400 °C), which confirmed that the process is applicable for depositing high quality SiN films on both planar and 3D substrate topographies.
三维（3D）鳍式场效应晶体管（finFET）的出现和新型存储技术的涌现，对用于器件制造中各种应用的氮化硅（SiN）薄膜的处理提出了严格的要求。在许多情况下，需要低温（<400°C）沉积工艺，以获得高质量的 SiN 薄膜，该薄膜具有抗蚀刻性，并且在 3D 衬底形貌上生长时也具有保形性。在这项工作中，我们使用单氨硅烷前体二（仲丁基氨基）硅烷（DSBAS，SiHN（Bu））和 N 等离子体开发了一种用于 SiN 的新型等离子体增强原子层沉积（PEALD）工艺。已经在很宽的阶段温度范围内（100-500°C）分析了材料性能，并将其与我们之前使用双氨硅烷前体双（叔丁基氨基）硅烷（BTBAS，SiH（NHBu））和 N 等离子体沉积的 SiN 获得的性能进行了比较。与文献中报道的其他工艺相比，在平面衬底上，在低温（<400°C）下即可获得具有低 C、O 和 H 含量的致密膜（约 3.1 g/cm）。该工艺还用于在高纵横比（4.5:1）3D 沟槽纳米结构上沉积 SiN 薄膜，以研究与最先进的器件结构相关的薄膜保形性和湿法蚀刻抗性（在稀释氢氟酸中，HF/HO=1:100）。薄膜保形性低于>95%的所需水平，这归因于氮等离子体软饱和、自由基物种重组以及离子方向性在 3D 衬底上沉积 SiN 时共同作用的结果。然而，在低温（<400°C）下沉积的最保形的薄膜的顶部、侧壁和底部沟槽区域观察到非常低的湿法蚀刻速率（WER≤2nm/min），这证实了该工艺适用于在平面和 3D 衬底形貌上沉积高质量的 SiN 薄膜。
