A composition for selectively etching inorganic oxides with respect to titanium includes an oxidizing agent, a buffered aqueous solution of hydrofluoric acid, a tetrazolium salt and sufficient organic solvent to make a stable solution. During the etching process, tetrazolium cations are reduced to form an etch insoluble formazan dye which deposits upon negatively charged(cathodic)sites, thereby suppressing galvanic corrosion.
Thin films of reactive metals in contact with layers of more noble metals, are etched by an etchant including a reactive cathodic inhibitor. The etchant is a hydrofluroric acid-based composition with hydrogen peroxide, a water soluble tetrazolium compound (the inhibitor) and a surface modifier, such as an alcohol or a more complex surfactant. For exemplary compositions, the undercutting of masking layers of noble metals or photolithographic materials is limited to the same order as the reactive metal film thickness.
The present invention is directed to a novel etching process for a semiconductor material which inhibits corrosion of metal comprised of pretreating the material, preferably with a surfactant, and then exposing the material to a mixture comprising salt, a buffered oxide etch, and optionally a surfactant.
Semiconductor substrates are treated in a treating solution consisting of hydrofluoric acid, hydrogen peroxide and a purified water or in a treating solution consisting of hydrofluoric acid, ammonium fluoride, hydrogen peroxide and a purified water, wherein the treating solution preferably has a hydrofluoric acid concentration of 0.1 to 10 wt % and a hydrogen peroxide concentration of 0.1 to 15 wt %. A process for treating semiconductor substrates is provided according to this invention, which allows less inclusion of metallic impurities from the treating solution and has excellent ability of removing metallic impurities with a very small amount of microparticles deposited on the substrate. The number of microparticles deposited on the semiconductor substrates can be reduced to about 1/10 the level in the conventional process.
The present invention is directed to a novel etching process for a semiconductor material which inhibits corrosion of metal comprised of pretreating the material, preferably with a surfactant, and then exposing the material to a mixture comprising salt, a buffered oxide etch, and optionally a surfactant.
A method for controlling corrosion of metals, particularly ferrous-based metals in contact with aqueous systems is disclosed, which includes treating industrial waters with a tetrazolium salt of the general formula: ##STR1## wherein R.sub.1, R.sub.2 and R.sub.3 may be various organic or inorganic substituents, including monomers or oligomers of the above structure.
