| AVS 58th Annual International Symposium and Exhibition | |
| Applied Surface Science Division | Thursday Sessions |
| Session AS-ThM |
| Session: | Analysis of Insulators and Challenging Samples |
| Presenter: | Yoshinobu Kimura, Hitachi, Ltd., Japan |
| Authors: | Y. Kimura, Hitachi, Ltd., Japan H. Koyama, Hitachi, Ltd., Japan H. Makino, Hitachi, Ltd., Japan H. Shinada, Hitachi, Ltd., Japan Y. Mochizuki, Hitachi High-Technologies Corp., Japan H. Kazumi, Hitachi High-Technologies Corp., Japan |
| Correspondent: | Click to Email |
Electron emissions from poorly conductive specimen stimulated by photon and electron injections result in charging phenomena. These can cause distortion of data in electron spectroscopy and image artifacts in scanning electron microscopy because surface potential which influence the motion of emitted electron is modified by charging and change time dependently. Therefore, time dependence of electron emission yields are important for understanding of radiation induced charging of resistive materials.
In this study, we present the transient characteristics of electron emission from SiO2 using a new experimental facility (Pulsed Electron Microscope: PULSEM) built in the present work. Main feature of the PULSEM, as with electron beam testing system, is a beam blanking system attached below the condenser lens. The beam blanking pulses electron beam into the minimum number of 6 electrons under the condition of primary beam current Ip = 20 pA and beam-pulse-width tp = 50 ns. The Everhart-Thornley detector with high response scintillator, afterglow time of which is 0.5 ns, and with a photomultiplier is synchronized to the beam blanking system. Transient SE signal as a function of the number of injected electrons is obtained.
Time-dependent electron emission yield (σ) with the resolution of 30 ns is investigated as a function of the primary electron dose which is controlled by pulse duration (Δt) as well as primary energy (Ep). Quasi static emission yield, which assumed to be intrinsic electron emission in the absence of charging, is obtained under low dose condition of below 60 electrons with Ip = 20 pA and Δt = 500 ns. The maximum yield (σm) and its corresponding energy (Em) are 2.5 and 300 eV, respectively. With the increase in electron dose, s approaches unity due to a charging effect. Finally, we will present total electron emission yield curves in the range of Ep < 6 keV and 50 ns < Δt < 500 ms.