低压扫描电镜电介质二次电子MCP收集特性  

Secondary Electron MCP Collection Characteristics of the Dielectric in LVSEM

作　　者：汪春华[1] 李维勤[2] 

机构地区：[1]西安航空学院电气学院,西安710077 [2]西安理工大学自动化与信息工程学院,西安710048

出　　处：《微纳电子技术》2015年第3期191-196,共6页Micronanoelectronic Technology

基　　金：国家自然科学基金资助项目(11175140)

摘　　要：采用数值仿真和实验测量相结合的方法,研究了低压扫描电镜(LVSEM)检测电介质样品过程中二次电子的出射规律,获得了二次电子的出射特性和微通道板(MCP)收集器的接收特性。结果表明,二次电子的出射角度近似余弦分布;由于电子的散射、输运和积累电荷的作用,绝缘的电介质样品表面上方产生了空间负电位分布,沿法线方向电位先下降到最小值,然后又回升,并逐渐趋于零电位。在这种空间负电位分布所形成的表面电场的作用下,部分较低出射能量的二次电子会返回积累于样品表面。在收集器正电场的作用下,能够脱离样品表面局部正电场束缚且具有较大出射角度的二次电子更容易被收集,电介质样品MCP收集器的收集效率约为21%;降低收集电压可以有效提高收集效率。The emission law of the secondary electron in the process of the dielectric sample detec- ted by the low-voltage scanning electron microscope （LVSEM） was researched with the com- bined method of the numerical simulation and experimental measurement, and the emission charac- teristic of the secondary electron and the collection characteristic of the micro-channel plate （MCP） collector were obtained. The results show that the emitted angle of the secondary electron is ap- proximative cosine distribution. Due to the effects of the electron scattering, transport and stored charges, the negative space potential distribution can be generated above the insulating dielectric sample surface. The space potential decreases to the minimum value along the normal direction, and then increases and fina will return to and store on lly te the s tive space potential distribution. nds to zero. Some secondary electrons with lower emitted energy ample surface under the surface electric field formed by the nega- The secondary electrons with higher emitted angle and ability of escaping the bound of the local positive electric field from the sample surface are collected easily under the effect of the positive electric field for the collector. The collection efficiency of the die- lectric sample MCP collector is about 21%, and the decrease of the collection voltage can effec- tively increase the collection efficiency.

关 键 词：电介质 二次电子 收集效率 微通道板(MCP) 扫描电镜(SEM) 

分 类 号：TN407[电子电信—微电子学与固体电子学]