Subsurface damage

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. 

Fig. 11—Observation of subsurface damage, (a) Cross section HTEM images of surface undergoing collision for ten minutes, (b) Electron diffraction pattern from an amorphous area.

Some injected wastes are persistent health hazards that need to be isolated from the biosphere indefinitely. For this reason, and because of the environmental and operational problems posed by loss of permeability or formation caving, well operators seek to avoid deterioration of the formation accepting the wastes and its confining layers. When wastes are injected, they are commonly far from chemical equilibrium with the minerals in the formation and, therefore, can be expected to react extensively with them (Boulding, 1990). The potential for subsurface damage by chemical reaction, nonetheless, has seldom been considered in the design of injection wells. 

Wu, H.Z., Roberts, S.G. and Derby, B. Residual stress and subsurface damage in machined alumina and alumina/silicon carbide nanocomposite ceramics , Acta Mater. 49 (2001) 507-517. 

PCA CHARACTERIZATION OF RESIDUAL SUBSURFACE DAMAGE AFTER SILICON WAFER MIRROR POLISHING AND ITS REMOVAL... 

The indent size, the surface crack morphology, and the extent of subsurface damage are all influenced by the crystal structure, chemical composition, and micro-structural morphology of the material. 

B. J. Hockey, Observations by transmission electron microscopy on the subsurface damage produced in aluminum oxide by mechanical polishing and grinding, Proc. Br. Ceram. Soc. 1972,20,95-115. 

Texturing and removal of contact-machined directional surface finish and subsurface damage... 

In conclusion, crack size can be estimated theoretically by Equation 9.2 when the load exceeds a certain critical value, which can be determined by Equation 9.3. The important parameters for the critical loads to propagate subsurface damage are presented in Table 9.1 (Bandyopadhyay et al., 1999). In achieving the plastic deformation process, the grain load for SiC and Si3N4 should be less than 0.2 N and 0.7 N, respectively. SEM and AFM techniques permit to evaluate the surface and subsurface fracture damage. 

Critical Loads Required to Propagate Subsurface Damage... 

Ceramic materials are commonly brittle materials with varying degrees of brittleness. The aim of this research is to increase the ductility of HPSN ceramic materials by the aid of laser preheating process and in process. With this method, it will be possible to increase the depth of cut (productivity of the process) more than 20 times and at the same time, keep the process in the ductile mode (free of surface and subsurface damages). 

Future research will seek to increase the depth of cut while maintaining the ductile grinding model and minimizing surface roughness and subsurface damage. 

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