Substrate influence in Young's modulus determination of thin films by indentation methods: Cubic boron nitride as an example
Substrate influence in Young's modulus determination of thin films by indentation methods: Cubic boron nitride as an example
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DOI：
10.1016/j.surfcoat.2006.08.124
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发表时间：
2006-12-04
影响因子：
5.4
通讯作者：
Ziemann, P.
中科院分区：
文献类型：
--
作者：
Richter, F.;Herrmann, M.;Ziemann, P.
本文以立方氮化硼（c-BN）为例，用压痕法测定了薄膜的杨氏模量。这是一个不平凡的任务，因为这种材料的杨氏模量接近金刚石压头。从文献结果的分析表明，杨氏模量的c-BN薄膜通常明显小于体材料值。我们给出的原因，这是至少在很大程度上由于测量问题，特别是没有适当的校正基板influence.In实验部分，我们已经使用纳米压痕与球形和三面锥体（Berkovich）压头获得的数据，并采用两个标准（奥利弗和法尔）和自己的理论方法（图像加载法，ILM）的数据评估。两组样品进行了研究：i）一个1.8 μ m厚的多晶c-BN薄膜的硅，这是很好的粘附由于一个梯度（B，C，N）夹层，和ii）异质外延c-BN薄膜的单晶金刚石。多晶c-BN膜具有使用ILM测定的800 +/-30GPa的杨氏模量。相比之下，上述标准方法对于1.3%的压痕深度与膜厚度之比提供了达到775 GPa的深度依赖性模量。对于金刚石上的456 nm异质外延膜，测得的模量为900 +/- 100 GPa，这非常接近c-BN块体材料的值。这表明，ILM提供了可靠的结果，没有明显的基板影响，也在一个复杂的情况下，超硬膜上的一个更柔顺的基板（硅），以及在更硬的金刚石基板。文章的最后，我们讨论了方法的局限性和克服它们的可能性。(c)2006 Elsevier B. V.保留所有权利。
This paper deals with the determination of Young's modulus of thin films by indentation methods using cubic boron nitride (c-BN) as an example. This is a non-trivial task because the Young's modulus of this material comes close to that of the diamond indenter. An analysis of results from literature revealed that Young's moduli of c-BN thin films are generally distinctly smaller than bulk material values. We give reasons that this is at least to a large extent due to measuring problems, in particular the absence of a proper correction of substrate influence.In the experimental part we have used nanoindentation with spherical and three-sided pyramidal (Berkovich) indenters to obtain the data, and employed both standard (Oliver and Pharr) and own theoretical methods (Image Load Method, ILM) for data evaluation. Two groups of samples were investigated: i) a 1.8-mu m thick polycrystalline c-BN film on silicon which was well-adherent thanks to a graded (B,C,N) interlayer, and ii) heteroepitaxial c-BN thin films on single-crystal diamond. The polycrystalline c-BN film had a Young's modulus of 800 +/- 30 GPa as determined using the ILM. In contrast the standard method mentioned above delivered a depth-dependent modulus reaching 775 GPa for a indentation depth to film thickness ratio of 1.3%. For the 456 nm heteroepitaxial film on diamond a modulus of 900 +/- 100 GPa was measured which is very close to c-BN bulk material values.It was demonstrated that the ILM delivers trustworthy results without noticeable substrate influence also in the complicated cases of a superhard film on a much more compliant substrate (silicon) as well as on the even stiffer diamond substrate. Concluding the article we discuss limits of the method and possibilities to overcome them. (c) 2006 Elsevier B.V. All rights reserved.