Thickness In Film

Thickness is one of the most important parameter of a thin film to be characterized since it plays an important role in the film properties unlike in bulk material. Microelectronic applications generally require the maintenance of precise and reproducible film metrology (i.e., thickness as well as lateral dimensions). Various techniques are available to characterize the film thickness which are basically divided into optical and mechanical methods, and are usually nondestructive. Film thickness may be measured either by in-sit monitoring of the rate of deposition or after the film deposition. Stylus profilometer is an advanced tool for thickness measurement of both thin and thick films after deposition (Fig. 3.10). It is capable of measuring

Pictorial view of the diffraction phenomenon is shown in figure 3.12. All the atoms in a lattice can be assumed to be as a part of set of planes characterized by three integers (h, k, l), referred to as the Miller indices. Within each set of defined planes the lattice points (atoms) are equally spaced throughout the plane. Equation (3.1) shows how the interplanar distances in a given crystal can be calculated from the measurements of the diffraction angles ‘θ’ and the known value of ‘λ’. After calculating the value of dhkl using equation (3.2) and applying certain rules (depending on the crystal strucuture) for determing the Miller indices h, k and l we can accurately find the lattice parameters of a crystal. For example the relation between the lattice parameters (a, b and c), Miller indices of (h, k and l) and the interplanar distance dhkl is for a simple cubic system is given

The electron beam passes through scan coils and objective lens that deflects the beam horizontally and vertically so that the beam scans the surface of the sample. As electrons penetrate the surface, a number of interactions occur that can result in the emission of electrons or photons from or through the surface. A reasonable fraction of the electrons emitted can be collected by appropriate detectors, and the output can be used to modulate the brightness of a cathode ray tube (CRT) whose x and y inputs are driven in synchronism with the x-y voltage rastering the electron beam. In this way an image is produced on the CRT; every point that the beam strikes on the sample is mapped directly on to a corresponding point on the screen. Linear magnification obtained can be calculated from the simple expression