Nanoscale chemical structure variations in nano-patterned and nano-porous low-k dielectrics: A comparative photothermal induced resonance and infrared spectroscopy investigation
Nanoscale chemical structure variations in nano-patterned and nano-porous low-k dielectrics: A comparative photothermal induced resonance and infrared spectroscopy investigation
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DOI：
10.1016/j.vibspec.2016.07.013
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发表时间：
2016-09-01
影响因子：
2.5
通讯作者：
King, Sean W.
中科院分区：
文献类型：
--
作者：
Hu, Qichi;Kjoller, Kevin;King, Sean W.
光热诱导共振(PTIR)技术的发展使基于原子力显微镜的红外(AFM-IR)光谱和成像技术在纳米尺度上得以实现。然而，由于瑞利衍射的限制，PTIR/AFM-IR与更传统的傅里叶变换红外(FTIR)光谱之间的直接对应对于纳米尺度的特征来说是被禁止的，后者被限制在几个微米的空间分辨率。在这方面，我们已经克服了这一挑战，通过使用标准的纳米电子制造技术在纳米多孔性低介电常数(即Low-k)非晶态无机-有机硅酸盐材料中制备了1 cm(2)90 nm宽的翅片阵列。利用这些结构，我们展示了AFM-IR、FTIR和GATR红外光谱之间的一般对应关系，以及这些技术对纳米方法在低k介电材料中诱导的化学结构纳米级变化的灵敏度的差异。为了进一步说明AFM-IR对纳米分辨率的化学结构变化的敏感性，将纳米级的低k介电材料暴露在额外的氧化等离子体灰尘清洗后的图案中。AFM-IR、FTIR和GATR测量结果都表明，随着等离子体灰清洗氧化电势的增加，低k介质中的端甲基浓度明显降低。这些结果进一步确立了AFM-IR进行纳米级红外光谱的能力，并表明AFM-IR与著名的微米级红外光谱技术如FTIR和GATR具有更强的一致性。(C)2016爱思唯尔B.V.保留所有权利。
The recent development of the photothermal induced resonance (PTIR) technique has enabled atomic force microscope based infrared (AFM-IR) spectroscopy and imaging to be achieved at the nanometer scale. However, a direct correspondance between PTIR/AFM-IR and more traditional Fourier transform IR (FTIR) spectroscopy has been prohibited for nanometer scale features due to Rayleigh diffraction constraints that limit the latter to few micron spatial resolution. In this regard, we have overcome this challenge by fabricating 1 cm(2) arrays of 90 nm wide fins in a nano-porous low dielectric constant (i.e. low-k) amorphous hybrid inorganic-organic silicate material using standard nano-electronic fabrication techniques. With these structures, we demonstrate both a general correspondance between AFM-IR, FTIR, and Germanium attenuated total reflection (GATR) IR spectroscopy, as well as differences in the sensitivities that these techniques exhibit to the nanoscale variations in chemical structure induced in the low-k dielectric by the nanopatterning method. To further illustrate the sensitivity of AFM-IR to changes in chemical structure with nanometer resolution, the nanopatterned low-k dielectric was exposed to additional oxidizing plasma ash cleans post patterning. Focusing on the Si-CH3 deformation band at similar to 1275 cm(-1), both the AFM-IR, FTIR and GATR measurements show a clear reduction in the concentration of terminal methyl groups in the low-k dielectric as the oxidation potential of the plasma ash clean increased. These results further establish the power of AFM-IR to perform nanoscale IR spectroscopy and demonstrates a stronger correspondance between AFM-IR and well-known micron scale IR techniques such as FTIR and GATR. (C) 2016 Elsevier B.V. All rights reserved.