Faculty of Electrical Engineering and Information Technology, Technical University Dresden, Helmholtz Straße 18, D-01069 Dresden, Germany.
Nanotechnology. 2013 Sep 6;24(35):355703. doi: 10.1088/0957-4484/24/35/355703. Epub 2013 Aug 12.
We have used the atomic force acoustic microscopy (AFAM) method to determine the indentation modulus of nanoporous thin-film materials with ultralow values of dielectric permittivity (dielectric constant k < 2.4). The AFAM method is based on the contact mode of atomic force microscopy (AFM) and as such is able to characterize materials with high spatial resolution. The tested material was porous organosilicate glass with nominal porosity ranging from 27% to 40%. The values obtained for the indentation modulus varied from 4 to 7 GPa depending on the pore concentration. The values obtained for the indentation modulus by use of the AFAM method were in very good agreement with those determined by nanoindentation. In addition, a part of the AFAM results obtained for the sample with the highest porosity content showed dependence of the effective indentation modulus on the applied load. Preliminary data analysis suggests that the stress rate is the critical factor in triggering this particular mechanical response of the porous material.
我们使用原子力声显微镜（AFAM）方法来确定具有超低介电常数（介电常数 k<2.4）的纳米多孔薄膜材料的压痕模量。AFAM 方法基于原子力显微镜（AFM）的接触模式，因此能够具有高空间分辨率来表征材料。测试材料为具有标称孔隙率为 27%至 40%的多孔有机硅玻璃。压痕模量的测量值根据孔浓度的不同而在 4 到 7 GPa 之间变化。使用 AFAM 方法获得的压痕模量值与纳米压痕法确定的值非常吻合。此外，对于具有最高孔隙含量的样品的一部分 AFAM 结果显示，有效压痕模量取决于施加的负载。初步数据分析表明，应力率是引发多孔材料这种特殊力学响应的关键因素。
