ABSTRACT

Two examples of cross-sectional samples that were prepared in an FEI FIB200 Workstation using the trench technique are shown in figure I. Figure la is a bright field image that demonstrates some of the high spatial selectivity with which samples can be

made on a routine basis. A number of different layers can be distinguished and it is apparent that only limited differential milling of the different phases has taken place. It is interesting to note that the columnar grained Ti and TiN making up the barrier layer are both fully continuous but that there is a thin band of oxide located at the interface between the lower part of the barrier layer and the underlying PtSi. The presence of this anomalous zone was found to be controlling the poor resistivity of the via. Figure I b gives a second example of an FIB prepared TEM slice and shows part of a Zr02 layer formed at the surface of a ZrNb alloy used in the nuclear power industry. Such interfaces are notoriously difficult to retain in samples prepared using broad beam Ar ion milling procedures partly because of the propensity of the metal to absorb H during the milling [14]. No such difficulties are encountered in the FIB , and figure lb shows part of a small nodule in the oxide that was found to be associated with a localised increase in the compressive stress of the oxide that has been relieved with the formation of a vertical crack (at A).