Study of Transmission Electron Microscope Sample Preparations Using Focused Ion Beam

Abstract

Focused ion beam has replaced conventional mechanical methods to prepare TEM sample, which is paramount in the industry for failure analysis. It reduces the turn-around time significantly, increasing the efficiency of the TEM and the overall failure analysis processes. FIB has drawback, however, in terms of the sample quality produced which becomes significant as feature size decreases. This thesis discusses low energy FIB for use in nanometer-scale technology. The normally used accelerating voltage, 30keV, produces too large amorphous layer at both sides of the sample in this small technology node, which degrades or even renders the image undecipherable for analysis. Some practical guidelines are derived for the real life applications. Besides, RC delay increases as technology node goes down. Low-k materials are used as dielectric isolation in order to reduce the capacitance, and thus the delay. Under the electron beam exposure, the low-k material becomes defective, i.e. it delaminates from the metal lines and shrinks. This phenomenon and the effect of sample thickness on it are also studied further in this thesis.