DIELECTRIC STRIP ISOLATION FOR JFET OR MESFET DEPLETION-MODE BUCKET-BRIGADE CIRCUIT

Undesired coupling of JFET or MESFET bucket-brigade stages through the epitaxial layer in a monolithic integrated bucket-brigade circuit is prevented by isolating adjacent stages by strips of thick oxide dielectric material such as SiO2. The dielectric strips are formed by selective oxidation to obtain local conversion of the n-type silicon epitaxial layer to SiO2. In a second embodiment, elongated spaced-apart mesas of the SiO2 are formed on the substrate prior to forming the patterned n-type silicon epitaxial layer. The storage capacitors of the bucket-brigade stages are MOS devices formed by metal layers overlapping the drain electrode regions of the JFETs or MESFETs diffused in the epitaxial layer with the dielectric material being a SiO2 layer therebetween.