Grace的進修雜記:)

Abstract
A Focused Ion Beam (also know as FIB) uses gallium (Ga) as an ion gas source. A negative electric field applied to the gallium source causes Ga ions to be released. These ions are focused into a small beam by two electric fields that act as lenses. Manipulation of the first lens’s pore size determines the size of the ion beam, while the secondary lens focuses on the surface of the specimen. A finely controlled beam of positive ions is shot onto the surface of a material, and then measures the electrons that are knocked from the surface. By mapping the electrons, the user can produce an image of the surface. The FIB is a great machine, which can cut and deposit materials and etch through metals.
Introduction
The purpose of this experiment is to cut and etch patterns on a silicon sample. Before using FEI FIB 611, students may want to understand how a FIB works. In short, the first word, “Focused,” means that the ion beam is focused. The second word, “ Ion,” refers to the ionized gallium, and the third word, “ Beam,” refers to stream of ions moving in the same direction. Lens one controls the beam current, and lens two focuses the ion beam. The FIB combines an ion column focused ion gun, a vacuum system, and a control system. The control system includes a stage, coordination systems, and a user interface for a controlling the auxiliary gas and the rest of the machine. Because the FIB operates in a high vacuum, the sample size type has certain limitations. The vacuum is necessary because, as the number of air molecules decreases, so does the interference on the ion beam. The mean free path for the ion increases with a higher vacuum. When there are fewer air molecules, there is less interference on the ion beam. A FIB is the use of an electric field to accelerate the ion beam through the electrostatic lens to focus the high-energy ion bombardment on the surface of the test sample. According to the type of reaction gas and the purpose of etching and deposition, whereby the FIB can detect the secondary electron imaging.
FIB 611 can produce a high brightness Ga ion source, and the ion beam travels at very high speed to impact the surface of the sample; as a result, this action disrupts the latticework of the atom formations, and the surface can sputter or form defects.