Vapor etching

A method was reported whereby CDC was produced from TiC and SiC and then subsequently treated in a water/argon mixture at 900°C [78,79], This activation was found to increase the pore size, surface area, and capacitance. Even though there is more complexity to the synthesis, this was a desirable method to increase the capacitance due to the fact that TiC and SiC are the least expensive carbides. Another method of pore widening involves inhitrating the pores with water and rapidly heating the infiltrated carbon above the temperature where water vapor etches carbon [80], The objective of this method was to selectively widen only the smallest pores. 

Anguita, J. Briones, F. HF/H2O vapor etching of Si02 sacrificial layer for large-area surface-micromachined membranes. Sens. Actuators A 1998, 64 (3), 247-251. 

Midgley and Dharmadhikari (1964) described methods of point counting polished sections of clinkers, using an HF vapor etch and 1000 to 2000 points. These authors stated that the standard deviation of the alite and belite weight percentages were estimated at 1.0 and 1.5, respectively, and that the microscopical method is as accurate as that obtained from Bogue calculations and better than that from X-ray diffraction. 

Agekyan VF, Stepanov YA, Emtsev VV, Lebedev AA, Poloskin DS, Remenjmk AD (1999) Effect of y irradiation on the photoluminescence kinetics of porous silicon. Semiconductors 33 1315-1317 Aouida S, Saadoun M, Ben Saad K, Bessais B (2006) UV photooxidation induced structural and photoluminescence behaviors in vapor-etching based porous silicon. Mater Sci Eng C 26 495 99... 

Porous Silicon Formation by HNO3/HF Vapor Etching... 

Fig. 1 Setup scheme of the HNO3/HF vapor-etching technique (Saadoun et al. 2002)...

Figure 3 illustrates SEM front views of HNO3/HF vapor-etched Si substrates, which in turn show the electrochemical heterogeneity of vapor etching. 

Figure 5 shows SEM view of (NH4)2Sip6 prepared at different HNO3/HF vapor-etching conditions. As has been previously said, the HNO3/HF volume ratio (Fig. 2) could be adjusted to favor either the formation of PS or a (NH4)2SiF6 (WP). In order to obtain the WP as a majority part, p-type silicon wafers were vapor-etched at a HNO3/HF volume ratio > 1/4. 

Fig. 6 SEM cross-sectional views of two grooved structures (a) hemispherical grooves made from monocrystalline silicon, (b) flow channels produced from poly- and monocrystalline siUcon (Ben Jaballah et al. 2005), and (c) UNO3/HF vapor-etched NaOH-textured c-Si wafer (Saadoun et al. 2011)...

The use of HNO3/HF vapor etching as an intermediate step to control the thinning and the surface smoothening of silicon nanopillars (Kalem et al. 2009). 

HNO3/HF vapor etching can be advantageous for biosensor fabrication due to reduction in cost and easy scalability (large-area PS layers can be easily fabricated) (Maia et al. 2007). 

Ben Rabha M, Hajjaji A, Bessais B (2012) Improvement of multicrystalline silicon solar cell performance via chemical vapor etching method-based porous silicon nanostructures. Sol Energy 86 1411... 

Fig. 1 (a) EE-based nanoporous pyramidal plane applied in pyramidal-textured Si solar cells (Kim et al. 2009). (b) SEM cross-sectional view of a gold-coated thin PS film prepared from HNO3/HF vapor etching (Ben Jaballah et al. 2005). (c) Cross-sectional SEM image of porous nanocrystalline (pnc) Si membrane imaged on the surface of a metalized silicon wafer revealing the cylindrical nature of the pores (Kavalenka et al. 2012)... 

Ben Jaballah A, Hassen M, Hajji M, Saadoun M, Bessais B, Ezzaouia H (2005) Chemical vapor etching of silicon and porous silicon silicon solar cells and micromachining applications. Phys Stat Sol (a) 202(8) 1606... 

As shown in Fig. 5.11, there are many different methods that could be used for Si porosification. It was established that, besides conventional electrochemical etching, chemical stain etching, chemical vapor etching, spark processing, laser-induced etching, and reactive ion etching could be used. 

Anodic Etching Chemical Stain Etching Chemical Vapor Etching Laser-Induced Etching Metal-Assisted Etching Spark Processing Reactive Ion (Plasma) Etching... 

Chemical etching (cleaning) The removal of material by chemical reaction with a fluid (wet chemical etching) or vapor (vapor etching) to produce a soluble or volatile reaction product. The etch rate is affected by the density, porosity, and composition of the film. 

Plasma etcher (semiconductor processing) A vapor etching system that uses a plasma to... 

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