School of Advanced Materials Science and Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do 16419, Republic of Korea.
Plasma Research Laboratory, School of Physical Sciences and NCPST, Dublin City University, Dublin D9, Ireland.
ACS Appl Mater Interfaces. 2023 Jun 14;15(23):28763-28771. doi: 10.1021/acsami.3c02950. Epub 2023 Jun 3.
Plasma enhanced atomic layer deposition (PEALD) of silicon nitride (SiN) using very high frequency (VHF, 162 MHz) plasma source was investigated at the process temperatures of 100, 200, and 300 °C. Two aminosilane precursors having different numbers of amino ligands, bis(-butylamino)silane (BTBAS) and di(-butylamino)silane (DSBAS), were used as Si precursors. A comparative study was also conducted to verify the effect of the number of amino ligands on the properties of SiN film. At all process temperatures, DSBAS, having one amino ligand, performed better than BTBAS in various aspects. SiN films deposited using DSBAS had lower surface roughness, higher film density, lower wet etch rate, improved electrical characteristics, and higher growth rate than those deposited using BTBAS. With the combination of a VHF plasma source and DSBAS with one amino ligand, the SiN films grown at 300 °C exhibited low wet etch rates (≤2 nm/min) in a dilute HF solution (100:1 of deionized water:HF) as well as low C content below the XPS detection limit. Also, excellent step coverage close to 100% on high aspect ratio (30:1) trench structures was obtained by using VHF plasma, which could provide sufficient flux of plasma species inside the trenches in conjunction with DSBAS having fewer amino ligands than BTBAS.
采用甚高频（VHF，162 MHz）等离子体源，在 100、200 和 300°C 的工艺温度下，研究了氮化硅（SiN）的等离子体增强原子层沉积（PEALD）。使用两种具有不同氨基配体数的氨硅烷前体，即双（正丁基氨基）硅烷（BTBAS）和二（正丁基氨基）硅烷（DSBAS）作为 Si 前体。还进行了对比研究，以验证氨基配体数对 SiN 薄膜性能的影响。在所有工艺温度下，具有一个氨基配体的 DSBAS 在各个方面都优于具有两个氨基配体的 BTBAS。使用 DSBAS 沉积的 SiN 薄膜具有较低的表面粗糙度、较高的薄膜密度、较低的湿法蚀刻速率、改善的电特性和较高的生长速率，优于使用 BTBAS 沉积的 SiN 薄膜。通过使用 VHF 等离子体源和具有一个氨基配体的 DSBAS 的组合，在 300°C 下生长的 SiN 薄膜在稀 HF 溶液（去离子水：HF 的 100:1）中具有较低的湿法蚀刻速率（≤2nm/min）以及低于 XPS 检测限的低 C 含量。此外，通过使用 VHF 等离子体，在高纵横比（30:1）沟槽结构上获得了接近 100%的优异台阶覆盖度，这是因为 VHF 等离子体与 BTBAS 相比，具有更少的氨基配体的 DSBAS 能够为沟槽内部提供足够的等离子体物种通量。
