Investigation of the Physical Properties of Plasma Enhanced Atomic Layer Deposited Silicon Nitride as Etch Stopper,ACS Applied Materials & Interfaces

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Investigation of the Physical Properties of Plasma Enhanced Atomic Layer Deposited Silicon Nitride as Etch Stopper
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2018-11-28 00:00:00 , DOI: 10.1021/acsami.8b15291
Harrison Sejoon Kim ₁ , Xin Meng ₂ , Si Joon Kim ₃ , Antonio T. Lucero ₁ , Lanxia Cheng ₁ , Young-Chul Byun ₁ , Joy S. Lee ₁ , Su Min Hwang ₁ , Aswin L. N. Kondusamy ₁ , Robert M. Wallace ₁ , Gary Goodman ₄ , Alan S. Wan ₄ , Michael Telgenhoff ₅ , Byung Keun Hwang ₅ , Jiyoung Kim _{1,

2}

Affiliation

Correlations between physical properties linking film quality with wet etch rate (WER), one of the leading figures of merit, in plasma-enhanced atomic layer deposition (PEALD) grown silicon nitride (SiN_x) films remain largely unresearched. Achieving a low WER of a SiN_x film is especially significant in its use as an etch stopper for technology beyond 7 nm node semiconductor processing. Herein, we explore the correlation between the hydrogen concentration, hydrogen bonding states, bulk film density, residual impurity concentration, and the WERs of PEALD SiN_x using Fourier transform infrared spectrometry, X-ray reflectivity, and spectroscopic ellipsometry, etc. PEALD SiN_x films for this study were deposited using hexachlorodisilane and hollow cathode plasma source under a range of process temperatures (270–360 °C) and plasma gas compositions (N₂/NH₃ or Ar/NH₃) to understand the influence of hydrogen concentration, hydrogen bonding states, bulk film density, and residual impurity concentration on the WER. Varying hydrogen concentration and differences in the hydrogen bonding states resulted in different bulk film densities and, accordingly, a variation in WER. We observe a linear relationship between hydrogen bonding concentration and WER as well as a reciprocal relationship between bulk film density and WER. Analogous to the PECVD SiN_x processes, a reduction in hydrogen bonding concentration arises from either (1) thermal activation or (2) plasma excited species. However, unlike the case with silane (SiH₄)-based PECVD SiN_x, PEALD SiN_x WERs are affected by residual impurities of Si precursors (i.e., chlorine impurity). Thus, possible wet etching mechanisms in HF in which the WER is affected by hydrogen bonding states or residual impurities are proposed. The shifts of amine basicity in SiN_x due to different hydrogen bonding states and the changes in Si electrophilicity due to Cl impurity content are suggested as the main mechanisms that influence WER in the PEALD processes.

中文翻译：

等离子体增强原子层沉积氮化硅作为刻蚀阻挡层的物理性能研究

在等离子体增强的原子层沉积（PEALD）生长的氮化硅（SiN _x）膜中，将膜质量与湿蚀刻率（WER）（一项优异的性能指标）联系在一起的物理性能之间的相关性尚待研究。实现SiN _x膜的低WER特别重要的是，将其用作7 nm节点半导体工艺以外的技术的蚀刻停止层。在此，我们探索中的氢浓度，氢结合状态，堆积膜密度，残留的杂质浓度，和PEALD的SiN的WERS之间的相关性_X使用傅里叶变换红外光谱法，X射线反射率，和椭圆偏振光谱法等PEALD的SiN _X使用六氯乙硅烷和空心阴极等离子体源在一系列工艺温度（270–360°C）和等离子体气体成分（N ₂ / NH ₃或Ar / NH ₃）下沉积用于本研究的膜，以了解氢浓度的影响，氢键状态，体膜密度和WER上的残留杂质浓度。氢浓度的变化和氢键合状态的差异会导致不同的体膜密度，从而导致WER的变化。我们观察到氢键浓度与WER之间的线性关系，以及体膜密度与WER之间的相互关系。类似于PECVD SiN _x在这些方法中，氢键浓度的降低是由于（1）热活化或（2）等离子体激发的物质引起的。但是，与基于硅烷（SiH ₄）的PECVD SiN _{x的情况不同}，PEALD SiN _x WER受Si前体的残留杂质（即氯杂质）影响。因此，提出了在HF中WER受氢键状态或残留杂质影响的HF中的可能的湿法蚀刻机制。在PEALD工艺中影响WER的主要机理被认为是由于不同氢键态引起的SiN _x中胺碱度的变化以及由于Cl杂质含量引起的Si亲电性的变化。

更新日期：2018-11-28

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