Junction delineation

Etchants for defect and junction delineation are usually composed of HF and an oxidizing agent such as HN03 [Dal, Gr4, Ka4, Nel], K2Cr207 [Se5] or Cr03 [Sil, Jel, Sc7, Ya4, Me5]. Alkaline solutions are rarely used for defect delineation [Mal2], An etch pit will form on a silicon surface if the dissolution rate is enhanced locally. Enhancement of the etch rate may occur for various reasons ... 

The interest of metal deposition on silicon from fluoride solutions arises from several areas plating processes (usually as the activation step) [1], tools for silicon characterization (defect revealing, junction delineation) [2] or studies of the damaging effects due to metallic contaminants in cleaning solutions [3]. 

The very first studies of mesoporous silicon noted the different colors of anodized and so-called stain films (Uhlir 1956 Turner 1958 Archer 1960). Uhlir referred to his surfaces as having a matte black, brown or red deposif (Uhlir 1956). Turner commented that several orders of interference colors can be seen as the film thickens (Turner 1958). The first use of such colored silicon in the late 1950s was in p-n junction delineation (lies and Coppen 1958 Whoriskey 1958 Robbins 1962). Porous silicon, with its lower refractive index than solid silicon, induces optical interference effects as etched films on wafers. A colorimetric analysis for layer thicknesses below 500 nm, at quantified porosities, showed that interference color directly related to the optical thickness of anodized singlelayer structures (Lazarouk et al. 1997). Figure 1 shows examples for stain-etched p + wafers. The visual color of a given layer can be further changed by plasmonic effects of deposited metal nanoparticles (Lublow et al. 2012) or through controlled oxidation of the silicon skeleton. 

In order to describe any electrochemical cell a convention is required for writing down the cells, such as the concentration cell described above. This convention should establish clearly where the boundaries between the different phases exist and, also, what the overall cell reaction is. It is now standard to use vertical lines to delineate phase boundaries, such as those between a solid and a liquid or between two innniscible liquids. The junction between two miscible liquids, which might be maintained by the use of a porous glass frit, is represented by a single vertical dashed line, j, and two dashed lines, jj, are used to indicate two liquid phases... 

Let us attempt to delineate the permeability coefficients of the tight junction and lateral space. Reintroducing Eq. (51), the permeability coefficient of the lateral space is... 

The FIF-CrOs etching system is widely used for defect sensitive etching and delineation of junctions between silicon layers of different doping concentrations. The etch rate of silicon in pure FIF solution is very low due to the lack of holes at the OCR Addition of CrOs increases the etch rate due to the increase of surface hole concentration resulting from the reduction of Cr. CrOs dissolves in water to form... 

C. Spinella and G. D Arrigo, Electrochemical etching of silicon A powerful tool for delineating junction profiles in silicon devices by transmission electron microscopy, J. Vac. Sci. Technol. B 18i 576, 2000. 

Conversion as a Junction of space time at 530 K and a feed ratio of 0.4. Such a curve would be delineated in an isothermal study by individual experiments involving runs at a series of space velocities. The points show experimental results with scatter similar to that discussed in Chapter 2. 

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