纳米压入法测试薄膜力学性能的若干关键影响因素分析

纳米压入法是目前薄膜等小体积MEMS(micro-electro-mechanical system)材料力学性能评定广为使用的方法,其测试可靠性严重依赖于仪器校准及对各种误差影响因素的消除和修正.文中以Oliver-Pharr数学评定模型为基础,对包括仪器柔度、压尖几何形状偏差、初始接触点位移、尺寸效应、基底、堆积和凹陷、蠕变、表面粗糙度等在内的薄膜弹性模量和硬度纳米压入测试时的若干关键影响因素进行分析.在此基础上,分别给出相应的处理办法和数据修正措施.研究表明,只有综合考虑这些因素的影响,方能获得准确的薄膜本征力学性能参数.

INVESTIGATION ON SEVERAL CRUCIAL FACTORS INFLUENCING THE MEASUREMENT OF MECHANICAL PROPERTIES OF THIN FILMS BY NANOINDENTATION TECHNIQUE

Nanoindentation technique is now widely used in evaluating the mechanical properties of small volume materials including thin films for MEMS(micro-electro-mechanical system) applications.However,the reliability of the evaluated results depends seriously on the observance of special measurement conditions and the elimination of undesired influences.Several crucial influencing factors relating to the errors in the measurements of hardness and elastic modulus by Oliver and Pharr method were investigated,such as instrument compliance,tip blunting,initial depth of penetration,size effect,substrate,material pile-up/sink-in,creep and suface roughness,etc.Then,the corresponding steps to avoid these problems in experiments and the correcting methods in data processing were presented separately.The results show that it is a key to obtain the accurate mechanical properties of thin films that the different influencing factors are of systemic consideration in nanoindentation measurements.