Self-limiting character of the involved surface reactions is essential for highly uniform and conformal growth in atomic layer deposition (ALD). However, the poor conformal coverage (<75%) that is often reported with silicon nitride (SiN_x) plasma enhanced ALD (PEALD) processes using metalorganic Si-precursors is confounding. In this article, we report our study of the SiN_x PEALD process using the tris-dimethylamino silane (3DMAS) precursor and forming gas (5% H₂–95% N₂) reactant plasma. For the substrate temperature (T_sub) range of 50 °C ≤ T_sub ≤ 150 °C, growth per cycle (GPC) for SiN_x deposition was found to approach saturation at 0.034 ± 0.001 nm/cycle though higher T_sub required longer 3DMAS exposures (t_A) for saturation. However, for T_sub > 150 °C, SiN_x GPC was seen to increase with t_A, indicating nonself-limiting growth from potential chemical vapor deposition-like side reactions emerging at higher temperatures. The refractive index (n) of 2.097 ± 0.003 at 2 eV with an optical bandgap of ∼1.7 eV determined from in situ spectroscopic ellipsometry measurements, and peaks s1 and n1 with ΔBE = 295.42 eV in Si2p and N1s XPS spectra measured on the capped SiN_x sample were found to agree with the optical constants and chemical characteristics reported for the silicon nitride material. SiN_x films deposited at T_sub = 250 °C (nonself-limiting) were found to be more resistant to ambient oxidation as compared to SiN_x PEALD films grown at T_sub = 100 °C. Although an entire 30 nm thick SiN_x PEALD film was oxidized after an unavoidable long ambient exposure, a cross-sectional transmission electron microscope image showed a conformal coverage of 95%–98% in a 3D trench structure with an aspect ratio of 4.5. Furthermore, higher resistance to ambient oxidation in plasma treated of SiN_x PEALD films demonstrates a potential of postgrowth treatments to improve desirable material properties without resorting to high-temperature processes.

中文翻译：

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用三-二甲基氨基硅烷前体解决氮化硅等离子体中的自限生长增强原子层沉积

所涉及的表面反应的自限制特性对于原子层沉积（ALD）中高度均匀和共形的生长至关重要。但是，使用金属有机硅前驱体的氮化硅（SiN _x）等离子体增强ALD（PEALD）工艺经常报告的不良保形覆盖率（<75％）令人困惑。在本文中，我们报告了我们对使用三-二甲基氨基硅烷（3DMAS）前驱体和形成气体（5％H ₂ –95％N ₂）反应物等离子体的SiN _x PEALD工艺的研究。对于基片温度（T_子）的范围内50℃≤Ť_子 ≤150℃，为的SiN每个周期（GPC）生长_X尽管较高的T _sub需要更长的3DMAS曝光时间（t _A）来达到饱和，但发现沉积在0.034±0.001 nm /周达到饱和状态。但是，对于T _sub  > 150°C，SiN _x GPC随t _A的增加而增加，表明在更高的温度下，潜在的化学气相沉积样副反应产生的非自限性增长。根据原位光谱椭偏测量，在2 eV时的折射率（n）为2.097±0.003，光学带隙为1.7 eV，在加盖的SiN上测得的Si2p和N1s XPS光谱中的s1和n1的峰s1和n1（ΔBE= 295.42 eV）_X发现样品与报道的氮化硅材料的光学常数和化学特性一致。 发现与在T _sub  = 100°C下生长的SiN _x PEALD膜相比，在T _sub = 250°C（非限制性）下沉积的SiN _x膜对环境氧化的耐受性更高。尽管在不可避免的长时间环境暴露后会氧化整个30 nm厚的SiN _x PEALD膜，但截面透射电子显微镜图像显示在纵横比为4.5的3D沟槽结构中，保形覆盖率为95％–98％。此外，在用SiN _x进行等离子体处理后，对环境氧化的抵抗力更高 PEALD膜证明了在不借助高温工艺的情况下进行后生长处理以改善所需材料性能的潜力。