NOVELTY - Printing paste for etching and optionally doping silicon dioxide or silicon nitride layers on silicon substrates comprises an etchant, a solvent, polymer or inorganic particles, and optionally an organic thickener, an acid and/or additives.    USE - The printing paste is useful in an etching process in which the paste is applied to a surface and then removed after 10 seconds to 15 minutes; in photovoltaics, semiconductor technology, high-power electronics, mineralogy, the glass industry, for producing photodiodes, viewing windows for instruments, glass supports for external use, for producing etched glass surfaces in the medical, decorative and sanitary sectors, for producing etched glass containers for cosmetics, foods and beverages, for marking containers, in sheet glass manufacture, for structuring glass for flat screens; in screen printing, stenciling, padding, stamping, inkjet printing and manual printing processes; for producing glass for solar cells or heat collectors; for etching glass articles or layers containing silicon dioxide or silicon nitride; for removing silicon dioxide or silicon nitride layers, for selectively opening passivating layers of silicon dioxide or silicon nitride to produce two-stage selective emitters and/or local p+ back surface fields; for opening passivating layers of silicon dioxide or silicon nitride in the manufacture of semiconductor components and circuits; for opening passivating layers of silicon dioxide or silicon nitride in the manufacture of components for high-power electronics; for mineralogical, geological and microstructural investigations (all claimed).    ADVANTAGE - Silicon dioxide or silicon nitride layers on silicon solar cells can be etched with fine structures, e.g. lines narrower than 100 microns    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for etching inorganic vitreous or crystalline surfaces by applying a printing paste as above and washing it off with a solvent or burning it off.