环境扫描电镜中电荷环境的测量

Evaluation of Charged Environments in Environment Scanning Electron Microscope

在环境扫描电镜(ESEM)中,采用高灵敏度的pA-表测试系统,测量法拉第杯,以及Cu-Zn合金、单晶Si、单晶Al2O3三种样品的样品电流(ISP)。ISP值反映出由电子流和离子流控制的ESEM样品室内的电荷环境。法拉第杯的ISP反映出入射电子和离子所控制的电荷环境;样品的ISP反映出入射电子、信号电子和离子所控制的电荷环境。由ISP值可确定ESEM在不同操作和环境条件下的离子化效率、离子化饱和程度,以及气体分子的散射作用。

The environment scanning electron microscope（ESEM） was modified, with a highly sensitive picoameter installed, to measure the current, Isp, of a Farad-cup and various samples,such as Cu-Zn alloy,Si and Al2O3. lsp was found to closely correlates to the charged state of the sample. ISp of charged Farad-cup originates from impinging of primary electrons and ions; whereas Isp of the charged sample results from primary electrons, signal electrons and ions. Moreover, lsp also provides interesting information related to ESEM, including ionization effcient and saturation, dectron scattering by gas molecules under different operating conditions.