Chemical etching gases

In the final chapter, Wei and Phillips tie together old and new results characterizing the processes of surface etching. They summarize evidence that chemical etching takes place by reactions of gas-phase free radicals. This subject pertains to catalyst redispersion and regeneration, and the chapter links the catalysis literature and literature less often consulted by catalytic scientists and engineers. 

The tin oxide thin film was patterned by reactive ion etching (RIE) using either SiCl or 1% H2 in N2 as the etch gas. The polysilicon contact holes were opened by wet-chemical etching in buffered hydrofluoric acid (BHF). A double-layer metallization (Cr -50 nm plus A1 -1 pm) was done by electron beam evaporation to form the electrical interconnection (Figure 1c). 

Raman spectra were measured on fresh, chemically etched surfaces in quasi-backscattering configuration using a triple DILOR XY spectrometer, a liquid nitrogen cooled CCD detector, and a 514.5-nm Ar-ion laser. The laser beam of power level 20 mW was focused on an area of 0.1 mm2 on the mirror-like plane (it was the (ab) plane of the single crystals). The measurements were performed in a cryostat with a helium gas atmosphere in the temperature range 5-295 K below temperature of metal-insulator phase transition. 

In reactive ion-beam etching (RIBE), the inert gas is replaced completely by a chemically reactive gas, so the sample is bombarded with a stream of ions that have a strong interaction with the substrate, and material removal can be very rapid. However, instrument corrosion can be a major concern. The ion gun, milling chamber, and pumping system are all exposed to large quantities of reactive gases and are prone to degradation. 

A technique that combines both physical and chemical etching mechanisms is chemically assisted ion beam etching (CAIBE). In CAIBE, an inert gas ion beam is directed at a sample which is situated in a... 

Commonly used adhesives for both PET and PBT substrates are isocyanate cured polyesters, epoxies, and urethanes. Surface treatments recommended specifically for PBT include mechanical abrasion and solvent cleaning with toluene. Gas plasma surface treatments and chemical etch have been used where maximum strength is necessary. 

The effectiveness of chemical etching is largely dependent on the volatility of fragmented species. For instance, oxygen plasma is an effective etching gas for most... 

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