A Newly Developed Fib System For Tem Specimen Preparation

Abstract

In the materials characterization using transmission electron microscope(TEM), FIB technique is demanding more and more as the method to prepare electron transparent specimen 1) . We have developed a dedicated FIB system FB-2000A employing FIB-TEM(STEM) compatible specimen stage 2) and an FIB micro-sampling tehnique [3][4][5] . The FIB-TEM(STEM) compatible specimen stage allowed site specific TEM specimen preparation with a positional accuracy of 0.1µm or better 2) . The FIB micro-sampling allowed extraction of TEM specimen directly from bulk sample without any pre-FIB preparation. Recently, an FIB system FB-2100 with a newly designed 40kV ion optics has been developed to perform high-speed TEM specimen preparation. Accelerating voltage is variable from 10kV to 40kV at a minimum step of 5kV. The maximum ion beam current and maximum ion beam current density of the new ion optics are 30nA and 25A/cm 2 , respectively. The ion milling speed in TEM specimen preparation is approximately twice as high as that of previous model (FB-2000A). No noticeable increase of beam damage for the TEM specimen preparation at 40kV has been confirmed. Figure 1 shows a high resolution TEM image of Si single crystal specimen prepared at 40kV. Crystal lattice and the dumb-bell structure with the spacing of 0.136nm are clearly observed. The requirements for a high-speed TEM specimen preparation are rapidly increasing. One of solutions is employment of automatic fabrication for rough milling of a TEM specimen. We have developed a new automatic fabrication system employing a new marker detection unit based on a phase only correlation(POC) method. The marker detection unit worked for various brightness and sharpness of the images. Figure 2 shows a series of test marker images observed at various images brightness. Images 2-8 were allowable in the marker detection. Figure3 shows a series of test images observed at various Z-position. All markers in these images were identified as the memorized marker. The newly designed ion optics allowed reduction of ion beam diameter together with increase of ion beam current. Minimum probe size and the probe current for the milling are 12nm and 0.02nA, respectively. Additionally, some optimization have been made in settings of voltages, lens for various sizes and accelerating voltages. Those improvements were effectively worked out to improve scanning ion microscopy(SIM) image quality. The SIM image resolution is 6nm or better at 40kV.

Transmission electron microtomography without the “missing wedge” for quantitative structural analysis

“…5 Â 5 Â 5 mm 3 ) trimmed from the bulk material was fixed on the top of a modified molybdenum grid mesh (called hereafter the ''mesh-pillar'') as shown by the arrow in Fig. 1(a) by the FIB microsampling technique [14]. The cubic specimen was carefully shaped by the FIB into a rod-form, as schematically shown in Fig.…”

FIB Damage in Silicon: Amorphization or Redeposition?

“…The specimen was removed from the FIB and sputter-coated with Cr to preserve the FIB milled damage layers. The specimen was put back into the FIB and the trenches were filled with CVD Pt deposition using a beam current of 100 pA. A cross-section TEM specimen was prepared across the trenches using the in-situ FIB lift-out method [10]. The specimen was observed using a Philips EM430 operating at 300 keV.…”

FIB Micro-Pillar Sampling Technique For 3D Stem Observation And Its Application

“…The rotation mechanism of the holder allows 360°turning of the conic stage around the ion beam axis of the FIB system and 360°turning perpendicular to the electron beam in the STEM. In this method, a piece of sample in a shape of pillar is extracted from the site to be characterized by the FIB micro-sampling method [1][2] . The extracted micro-pillar sample is transferred and mounted on the conical stage.…”