VERFAHREN ZUR HERSTELLUNG EINES DOTIERUNGSMITTELS FUER HALBLEITER

1485484 Semi-conductor devices TEXAS INSTRUMENTS Inc 13 Sept 1974 [19 Sept 1973] 40047/74 Heading H1K A conductivity type determining dopant is diffused into a semi-conductive wafer by applying to a surface of the wafer a composition comprising tetraethyl orthosilicate, acetic acid or acetic anhydride, and the dopant in a solvent, which composition has been refluxed to reach equilibrium, and heating the coated substrate to a temperature at which a silicon oxide layer containing the dopant is formed, and then heating to a diffusion temperature. The equilibrium mixture is stated to include ethyl acetate, diethoxysilicondiacetate and triethoxysilicon acetate. The solvent is preferably ethylalcohol. The composition may be applied by spinning, spraying or dipping. For a silicon wafer the dopant may be B, P, As or Au, the latter for lifetime control, included in the composition as boron oxide, orthophosphorio acid or P 2 O 5 , orthoarsenic acid or gold chloride respectively. For a gallium arsenide wafer, zinc may be included as zinc chloride.