The Dualbeam (FIB/SEM) and its Applications - Nanoscale Sample Preparation and Modification

Abstract

Summary form only given. The ability to modify samples and create structures at the `nano' level (<100 nm) is now a very well established science. However, the tools required to facilitate this technology are going through a constant evolution in order to keep up with the high demands of new applications. One such tool is the Dualbeam, which combines a field emission SEM column with a gallium source focussed ion beam (FIB) column. Previously used only in the semiconductor or `nano-electronics' industry, it is now a vital tool in creating, modifying, imaging and analysing structures at the nano scale. In fact Dualbeams systems are now used regularly in semiconductors, data-storage, research, industry and even biology. Having two beams offers tremendous advantages to the user. A SEM column is the ideal tool for sample inspection and for imaging at high resolution of specific features without the risk of sample damage. By aligning the SEM and FIB at a reference point the sample can be inspected non-destructively and a certain area of interest determined. Software patterns are used to control where and how the ion beam is scanning on the sample and therefore where material is being removed. The milled area can be imaged in real time by the electron beam while the milling is in progress. This `simultaneous patterning and imaging' can be very useful to carefully control the milling process, using the ion beam only for material removal and the electron beam for non-destructive observation. An extension of the imaging and milling capability is called Slice and View. This allows an image to be recorded each time a `slice' of material is removed by the ion beam. The result is a stack of images taken through a selected area of a sample, showing information in x, y and z dimensions. However, true 3D information can be seen if the images are processed using reconstruction software. One of the most important applications of a dualbeam is that of quality TEM sample preparation. With the aid of the electron beam - the ion beam can be placed very accurately and site specific TEM sample preparation is possible. Recently the development of Cs corrected TEM systems has meant that TEM sample quality is now of high importance if quality data is to be gained. Using low kV ion beam energies the sample damage often associated with high kV preparation can be virtually eliminated. In situ lift out techniques, such as the Omniprobe, allow the sample to be removed and attached to a grid inside the chamber, allowing for further thinning and polishing of the sample wherever necessary. The ion beam can also be used to modify or produce tools for use in a variety of applications. Examples might be the production of super fine needles in the medical field, for producing micro-indenters for materials research, or for creating/modifying an AFM tip. In many cases the combination of beams may produce the best results. For example, the AFM tip may be further enhanced by depositing a super fine tip of material on the end with the electron beam. Similarly, emitters for field ion microscopes can be prepared at site specific locations using FIB milling. An important application in the field of semiconductor development is that of device modification. Electronic circuits are shrinking at an incredible rate and in order to test or modify these circuits FIB and Dualbeam systems are indispensable. Device edit makes use of all the Dualbeams capabilities, ion beam milling, etching, deposition and even circuit testing. The Dualbeam is proving an indispensable tool in many nanotechnology applications. With the flexibility to choose either the ion or electron beam and the different properties that these beams have, many applications can be achieved in a single tool. In fact the Dualbeam can be considered a true nano-laboratory