Uniformity thickness

Dielectric Film Deposition. Dielectric films are found in all VLSI circuits to provide insulation between conducting layers, as diffusion and ion implantation (qv) masks, for diffusion from doped oxides, to cap doped films to prevent outdiffusion, and for passivating devices as a measure of protection against external contamination, moisture, and scratches. Properties that define the nature and function of dielectric films are the dielectric constant, the process temperature, and specific fabrication characteristics such as step coverage, gap-filling capabihties, density stress, contamination, thickness uniformity, deposition rate, and moisture resistance (2). Several processes are used to deposit dielectric films including atmospheric pressure CVD (APCVD), low pressure CVD (LPCVD), or plasma-enhanced CVD (PECVD) (see Plasma technology). 

Standard of deposition such as thickness uniformity, or defined thickness variation and coating defects. 

Figure 23. improvement of the relative thickness uniformity of a coating layer with the mask device shown in Fig. 22. Bottom curve without ma.sk. Top curves thickness uniromiiiy with several mask conligu-rations.

Wood chip quality (size and thickness uniformity)... 

Ellipsometry and profilometry Thickness, refractive index, and consolidation behavior during drying and crystallization. Thickness uniformity. 

Background on Spin Casting. As early as 1958, Emslie, et al. (A) proposed a theoretical treatment of spin casting for nonvolatile Newtonian fluids. This theory predicted that films formed on a flat rotating disc would have radial thickness uniformity. They predicted that the final film thickness would depend on spin speed (w) and viscosity (ij) as well as other variables such as liquid density and initial film thickness. The dependence of thickness on u> and ij was also recognized by many of the other authors reviewed in this paper, and their proposed relationships are compared in Table I. Acrivos, et al. (5) extended the Emslie treatment to the general case of non-Newtonian fluids, a category into which most polymers fall. Acrivos predicted that non-Newtonian fluids would yield films with non-uniform radial thickness. 

For epitaxial silicon wafers, product design focuses on optimizing the geometry of the plasma-enhanced, chemical-vapor-deposition (PECVD) reactor. To increase productivity, and maintain acceptable thickness uniformity, on the order of 5%, a simple optimization strategy locates a design that completes the deposition in 62 s. Then, for a standard manufacturing process, the economics are driven by the wafer costs, which are provided by a vendor at 206/wafer. At a sales price of 260/epitaxial wafer, the investor s rate of return is 18.3% and the return on investment is 25.3%. 

Recent results were able to demonstrate that the coatings produced by electrodeposition display the same coherence and layer thickness uniformity as those of composition-modulated alloys produced by vacuum evaporation or sputter deposition. 

For the ILD process, it is less feasible to continue measuring over field oxide, because multiple oxide layers are present (also see Fig. 6). The true thickness and thickness uniformity of the particular level of an ILD proeess can be confounded by the presence of the underlying previous layers. Thus, after the first metal process, it is preferable to measure the oxide thickness directly on a metal line. 

Last, but by no means least, reference should be made to the use of proteins in nano-fabrication [492]. One approach is illustrated by the fabrication of a 1-nm-thick metal film with 15-nm-diameters holes, periodically arranged on a triangular protein lattice [493]. Advantage was taken of the 10-nm-thick, uniformly porous surface (or S) layer of the crystalline protein obtained from the thermophilic bacterium Sulfolobus acidocaldarius. The protein was adsorbed from a dilute solution onto a molecularly smooth carbon-film surface, metal coated by evaporation, and ion milled to give spatial ordering of holes with the same nanometer periodicity as the protein lattice [493]. 

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