METODO PARA REDUCIR EL RUIDO ELECTRICO Y LA RESISTENCIA DE CONTACTO ENTRE LA CAPA RESISTENCIA Y LAS CAPAS DE RECUBRI- MIENTO EN LA PRODUCCION DE CIRCUITOS INTEGRADOS DE PELICULA DELGADA SOBRE UN SUBSTRATO.

摘要

1,228,956. Printed circuit assemblies. WESTERN ELECTRIC CO. Inc. 8 April, 1968 [13 April, 1967], No. 16777/68. Heading H1R. A method of manufacturing a thin film integrated circuit comprises forming on a substrate a resistor layer, a metallic oxide protective layer, a capacitor electrode layer and a highly conductive layer, sequentially etching the layers to delineate circuit components and heating the etched assembly. A high-alumina ceramic or glass substrate 10 has a layer 12 of tantalum nitride deposited thereon followed by a sputtered layer 14 of tantalum pentoxide or alternatively the oxide layer may be formed by anodizing the nitride layer. Beta tantalum layer 16 is then deposited on the tantalum pentoxide and lastly a conductive layer of aluminium 18 is applied to layer 16. Contact pads 20, leads and capacitor areas 22 are delineated by a photoresist and the remaining areas are etched to the tantalum pentoxide layer 14. The entire area is then patterned with photoresist to delineate resistors and the tantalum pentoxide layer 14 and nitride layer 12 are etched to form resistor 24. Areas which serve as conductors or pads retain the beta-tantalum 16 and the aluminium 18 but the capacitor areas 22 are stripped of the aluminium for subsequent anodization. After anodizing to form the dielectric of the capacitor and trim-anodizing the resistor patterns counter electrodes are deposited on the capacitors and cross-overs are formed. The assembly is then heated in the range 300‹ to 600‹ C. so that the protective layer of oxide diffuses into the adjoining tantalum nitride and tantalum layers so that the whole layer is rendered conductive and noisegenerating pin holes become unimportant. In addition the heating eliminates back etching normally performed on Ta 2 O 5 dielectrics and effects temperature coefficient adjustment of the resistors. Instead of using aluminium as an overlay, a nickel chromium alloy gold overlay may be used or just gold. The nickel and gold layers may be deposited by an electroless process. Reference has been directed by the Comptroller to Specification 1,125,394.