A technique for preparation of a pillar shaped sample and its multi-directional observation of the sample using a focused ion beam (FIB) / scanning transmission electron microscopy (STEM) system has been developed. The system employs an FIB/STEM compatible sample rotation holder with a specially designed rotation mechanism, which allows the sample to be rotated 360 degrees [1-3]. This technique was used for the three dimensional (3D) elemental mapping of a contact plug of a Si device in 90 nm technology. A specimen containing a contact plug was shaped to a pillar sample with a cross section of 200 nm x 200 nm and a 5 um length. Elemental analysis was performed with a 200 kV HD-2300 STEM equipped with the EDAX genesis Energy dispersive X-ray spectroscopy (EDX) system. Spectrum imaging combined with multivariate statistical analysis (MSA) [4, 5] was used to enhance the weak X-ray signals of the doped area, which contain a low concentration of As-K. The distributions of elements, especially the dopant As, were successfully enhanced by MSA. The elemental maps were reconstructed from the maps.

A novel technique for three-dimensional structural and elemental analyses using a dedicated focused ion beam (FIB) and scanning transmission electron microscope (STEM) has been developed. The system employs an FIB-STEM compatible sample holder with sample stage rotation mechanism. A piece of sample (micro sample) is extracted from the area to be characterized by the micro-sampling technique [1-3]. The micro sample is then transferred onto the tip of the stage (needle stage) and bonded by FIB assisted metal deposition. STEM observation of the micro sample is carried out after trimming the sample into a micro-pillar 2-5 micron squared in cross-section and 10 -15 micron in length (micro-pillar sample). High angle annular dark field (HAADF) STEM, bright field STEM and secondary electron microscopy (SEM) images are obtained at 200kV resulting in threedimensional and cross sectional representations of the microsample. The geometry of the sample and the needle stage allows observation of the sample from all directions. The specific site can be located for further FIB milling whenever it is required. Since the operator can choose materials for the needle stage, the geometry of the original specimen is not a limiting factor for quantitative energy dispersive X-ray (EDX) analysis.

A new focused-ion-beam (FIB) micro(μ)-sampling technique has recently been developed to facilitate transmission electron microscope (TEM) specimen preparation, while allowing chips or wafer samples to remain intact. A deep trench is FIB-milled to dig out a small, wedge-shaped portion of the sample (or a microwedge) from the samples area of interest, leaving a small, brige-shaped portion (or a microbridge) to support the microwedge. A metal needle is then manipulated into position for lifting the microwedge, i.e., the μ-sample. FIB-assisted deposition (AD) is used to bond the needle to the μ-sample. FIB-milling of the microbridge then separates the μ-sample from the chip or wafer. The separated μ-sample is mounted onto a TEM grid and secured using FIB-AD. The μ-sample is then FIB-thinned further, to a strip of about 0.1 μm thick. All of the above steps are accomplished under vacuum in the FIB system. This design permits a reliable and user-friendly environment for TEM specimen preparation, while keeping chips or wafer samples intact. It also permits operators to repeat TEM inspection and FIB-milling so that precise areas of interest may be made available for TEM inspection. Both cross-sectional and plan view TEM μ-sampling are feasible.