In-Situ TEM Observation of Electromagnetic Field in Some Real Materials
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In-Situ TEM Observation of Electromagnetic Field in Some Real Materials Katsuhiro Sasaki1, Zhouguang Wang2, Keiichi Fukunaga2, Tsukasa Hirayama2, Kotaro Kuroda1 and Hiroyasu Saka1 1 Dept. of Quantum Engineering, Nagoya University, Nagoya, Japan 464-8603 2 Japan Fine Ceramics Center, Nagoya, Japan 456-8587 ABSTRACT Electromagnetic fields presents in some real materials have been observed using electron holography and a simlpe method named the Shadow Image Distortion (SID) method which we have developed. The in-situ electron holography observation of the electric field surrounding a ceramic particle showed the rapid degradation of dielectric properties of the particle at an elevated temperature. The cross sectional view of mean electrostatic potential distributions in a silicon device has been observed. In-situ electron holography and SID observations showed the electrostatic potential distribution across a reverse biased p-n junction in a compound semiconductor. The SID method using a dedicated tool allowed single-step imaging of 2D maps of electromagnetic field. INTRODUCTION In the semiconductor industry, transmission electron microscopy (TEM) has played an increasingly important role for characterizing electric and/or magnetic device structures with decreasing dimensions[1]. In particular, characterizing the dynamic behavior of electromagnetic fields in a device is important to understand and control its properties. Two well-known methods are often used to observe the electromagnetic field in a TEM. One is electron holography [2], the other one is Lorentz microscopy[3]. We have been developing a simple method named the Shadow Image Distortion (SID) method[4]. In the first part of this paper, we summarize our development of in-situ electron holography. As a test case of in-situ electron holography, we present the observation of the electric field surrounding a ceramic particle at an elevated temperature[6,5]. The electron holographic technique using a TEM has been used to map and characterize two-dimensional electrostatic potential distributions across p-n junctions in silicon devices[7,8]. Due to unique advantages such as high accurate position selectivity, high process uniformity and high removal rate, the focused ion beam (FIB) technique is now widely used to prepare TEM specimens. A silicon metal-oxide-semiconductor field-effect transistor (MOSFET) sample sectioned directly from a silicon integrated circuit wafer was fabricated using a FIB to produce a cross-section, and electrostatic potential distributions in the transistor were examined by electron holography. Recently, the combination of FIB preparation and electron holography was used to successfully observe a p-n junction under reverse-bias condition in a Si/Si p-n junction film [9,10]. We have used the same techniques to perform an in-situ observation of potential distributions at a p-n junction in a reverse-biased GaP light emitting diode (LED) [11]. The interference region in the image of the electron hologram is limited to a narrow bund
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