Fibxtem— Focussed Ion Beam Milling for TEM Sample Preparation

Abstract

In the semiconductor industry, shrinking geometries and increasing process complexity have greatly increased the demand for TEM analysis of specific submicron regions. Until recently, samples of this nature have been difficult if not impossible to prepare. We have combined cross-sectional TEM sample preparation (XTEM) and the precise material sputtering of focussed ion beam milling (FIB) to thin samples to electron transparency. We call this sample preparation technique FIBXTEM.Three advantages of this technique are: 1) The area of interest can be analyzed in the scanning electron microscope before final thinning; 2) Any specific defect area becomes a candidate for TEM analysis, including failed sub-micron structures; and 3) Samples are generally artifact-free and of uniform thickness.Key elements of the FIBXTEM technique include precision planar polishing, unique holders for mounting and transferring samples between systems, and the FIB-induced deposition of a sacrificial protective layer over the area of interest during ion thinning.This technique extends the use of TEM analysis into new areas of semiconductor process development and failure analysis. Recent applications for materials problem solving and failure analysis are discussed.

Applications of the FIB lift-out technique for TEM specimen preparation

“…As a result, the application of this analytical technique continues to expand. One of the most valuable areas of interaction has been the preparation of specimens for transmission electron microscopy (TEM) (Assayag et al, 1993a,b;Basile et al, 1992;Black et al, 1992;Dickson et al, 1992;Hull et al, 1993Hull et al, , 1994Kirk et al, 1989;Lange and Czapski, 1991;Sandborn and Meyers, 1992;Stevie et al, 1995;Szot et al, 1992;Tarutani et al, 1992;Tomikawa and Shikata, 1993;Mendez et al, 1992;Nakajima et al, 1993;Overwijk et al, 1993;Yamaguchi et al, 1993). The concept of a lift-out method was first discussed by a group from Philips for semiconductor applications (Overwijk et al, 1993).…”

Focused ion beams techniques for nanomaterials characterization

“…Preparation of P-V Specimens P-V specimens have been made from a wide range of materials usually using methods based on the H-bar and the lift-out techniques (Tsutsumi et al, 1999;Basile et al, 1992;Rai et al, 2000). A cleaved or polished sample is mounted end-on in the FIB system and the P-V specimen is prepared at the edge of the sample.…”

Influence of material properties on TEM specimen preparation of thin films

“…However, only a small specimen transparent area is available and therefore tilts will be limited. Gas-assisted etching is most often used, which allows faster etching rates thereby increasing the size of the thin area, which, in turn, reduces the problems associated with limited tilts (Basile et al, 1992;Young et al, 1990).…”