Surface etched

A fonn of anisotropic etching that is of some importance is that of orientation-dependent etching, where one particular crystal face is etched at a faster rate than another crystal face. A connnonly used orientation-dependent wet etch for silicon surfaces is a mixture of KOH in water and isopropanol. At approximately 350 K, this etchant has an etch rate of 0.6 pm min for the Si(lOO) plane, 0.1 pm min for the Si(l 10) plane and 0.006 pm miiG for the Si(l 11) plane [24]. These different etch rates can be exploited to yield anisotropically etched surfaces. 

Etch Mechanisms. Most wet etches for the compound semiconductors employ oxidation of the semiconductor followed by dissolution of the oxide. For this reason, many wet etches contain the oxidant hydrogen peroxide, although nitric acid can also be used. One advantage of wet etching over dry is the absence of subsurface damage that is common with dry etching. Metal contacts placed on wet-etched surfaces exhibit more ideal characteristics than dry-etched surfaces. 

Surface modifications and surfiice roughness Cu, Mo, and Be laser mirrors atomic oxygen modified (corroded) surfaces and films, and chemically etched surfaces. 

Figure 8 SEM images of etched surfaces of blends with 50% stretching (a) sulfur cured (3000 x) and (b) peroxide cured (3000 X). Source Ref. 27.

This term is used both to describe designs that are etched or engraved in the mold surface and the process of inserting a printed film into the mold, to be produced as an integral component of the finished product. Etched surfaces can be drawn both parallel and perpendicular to a parting line of molds or postforming in an extrusion line.. However, be alert with molds to the fact that parallel to the parting line additional draft is required. A wide selection of patterns is available and new ones can be readily created. 

It was reported that high selectivity can be achieved with addition of small amount of O2, which increases the etch rate of metal electrode [4] while suppresses the etch rate of dielectrics [5]. Figure 2 shows the comparison of residues formation after etching between in (a) CI2 and (b) CI2/O2. Agglomerated residues were observed after etching in CI2/O2, indicating that addition of O2 (1%) enhances residues formation on the etched surface. 

Fig. 6. AFM images of etched surface of HfN films after 1% DHF dipping with the time (a) 5 s, (b) 15 s, (c) 40 s (d) SEM image of metal gate stack after etching 5min in 1% DFDF, showing HfN film is laterally etched.

The track density can be easily determined on a newly cut, polished, and etched surface by counting, under an optical microscope, the number of etched tracks in a measured area of the solid. The uranium concentration can be determined by a number of analytical techniques. Following these... 

FIG. 66. Auger spectra (A) freshly polished, oxidized, and contaminated (lll)Cd surface of a CdTe crystal (B) (lll)Cd surface after a 3-min etch in 1% Brj/CHjOH solution (C) Brj/CHjOH-etched surface after rinse in 1 mM H2SO4 at —0.1 V (D) (lll)Cd surface after electrochemical reduction at —2 V in mM H2SO4 for 10 min. (From Ref. 391.)... 

The reaction between A-chlorobenzotriazole and l-methyl-2-phenylindole involves formation of the indole radical cation and benzotriazole radical via an initial electron transfer <82JOC4895, 91JCS(P2)1779>. Chemical reactions of benzotriazole on a freshly etched surface of metallic copper are studied by surface-enhanced Raman scattering, x-ray photoelectron spectroscopy, and cyclic voltammetry. The surface product is (benzotriazolato)copper(-l-), which covers the surface in the shape of polymeric material and shows good anticorrosion effects for copper <91JPC7380>. 

Some of the modern surface analysis methods have been used to study the surface chemistry of both plasma etched surfaces and plasma polymerized thin films. Much of this work has involved exposure of these surfaces to air as the samples are transferred from the plasma system to the surface analysis system. However, in a few cases surface analysis has been performed in the plasma system after the plasma gas has been pumped away. This work will be discussed in more detail later in this chapter. 

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