Effects of Coating Thickness and Atomic Number on Backscattering Electron Signals in Metallic and Ceramic Substrates

• Main Authors: JimmyHuang, 黃俊銘
• Other Authors: Jui-Chao Kuo
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/07665745500883161716

碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 101 === This thesis will propose some methods to solve the oxidation problem on metals and charging problem on ceramics.We deposited a thin conductive film on the surface of substrates, then it would separate the directly contact with atmosphere for metals and conduct the electrons out of the surface for ceramics.But the coating thin film will interfere the incident electrons and block the backscattering electrons out of substrates, so we will discuss the relationship between the atmoic number, film thickness and electron signals. In the experiment, we chose the Al,Cu,Ag as metal substrates, Al2O3 ,ZrO2 ,CeO2 as ceramic substrates, and Al,Ni,Pt as coating materials. After sample preparation, we used e-beam deposition to coat thin film from 0 to 8 nm with 2nm a step. Then used FE-SEM to do EBSD mapping, and analyzed with TSL OIM Analysis 6, Image J. Furthermore, using CASIO 4.2 software to simulate the condition in SEM scanning to compete the result with experiment. According to the results, no matter what the metals or ceramics are, when increasing the substrate atomic number, the backscattering electron signals is stronger than small atomic number materials, and the signal descendant rate is slow. Additionally, we also discussd the effect of thin film thickness and their atomic number. First, we found that the thicker coating film, the faster signals decay rate. Second, the larger atomic number of coating materials, the higher descendant rate for backscattering electron signals. But we found a exception for Pt coating. Based on the Pt physical properties, the adhesion force for Pt is not quiet well when depositing on substrates, so it is easy to peel off or form the island structure. Owing to the film morphology, the cross-section area for inelastic collide is shrinking, then the interference on elastic backscattering electrons is also reduced. So compare with the rule of larger coating atomic number, larger signals decay rate, it is not suitable for Pt materials. Last but also the more important,the best condition for solving charging problme and oxidation problem is coating a thin film under 2nm. Even though the coating film will also dimish the backscattering electorn signals, it is still under the acceptable range for resolving by TSL OIM Analysis 6 software.