Fabrication of junction field effect transistor with filled grooves

The method of fabricating a junction field effect transistor comprising

• providing a substrate of semiconductor material of one conductivity type of relatively low resistivity having a flat planar surface;
• growing an epitaxial layer of semiconductor material of the one conductivity type of relatively high resistivity on said surface of the substrate, said epitaxial layer having a flat planar surface parallel to the interface of the epitaxial layer and the substrate, said epitaxial layer and said substrate forming a body of semiconductor material;
• introducing conductivity type imparting material of the one conductivity type into said epitaxial layer from said surface to form a layer of semiconductor material of the one conductivity type of relatively low resistivity in said epitaxial layer adjacent to said surface;
• forming a layer of a first protective material on the surface of the body;
• removing portions of said layer of first protective material to expose a plurality of parallel areas of said surface;
• removing semiconductor material at the exposed areas to form a plurality of grooves in said body of semiconductor material providing interposed ridges of semiconductor material, said grooves extending through said layer of semiconductor material of the one conductivity type of relatively low resistivity into the underlying layer of the one conductivity type of relatively high resistivity, each of said grooves having side walls formed by the adjacent ridges of semiconductor material and an end wall;
• treating the body of semiconductor material to convert semiconductor material except at the surface of the ridges of semiconductor material protected by said first protective material to a second protective material thereby forming a layer of said second protective material at the side walls and end walls of said grooves;
• removing the layer of said second protective material from the end walls of said grooves to expose the underlying semiconductor material of the one conductivity type of relatively high resistivity while leaving the layers of said second protective material at the side walls of the grooves;
• introducing conductivity type imparting material of the opposite conductivity type into the exposed semiconductor material at the end walls of said grooves, said conductivity type imparting material of the opposite conductivity type extending laterally to convert zones of said semiconductor material of the one conductivity type of relatively high resistivity to said opposite conductivity type and to produce channel regions of the one conductivity type of relatively high resistivity between said converted zones, the width of said channel regions being less than the width of the semiconductor material of said ridges of semiconductor material;
• applying conductive material to the end walls of said grooves to form first electrical connections in ohmic contact with said zones of the opposite conductivity type;
• filling said grooves with an inert nonconductive filler material extending beyond the surface of said ridges of semiconductor material;
• applying filler material to provide a flat planar surface parallel to the surface of said ridges of semiconductor material;
• removing a uniform layer of materials from said surface of the filler material to a depth to expose semiconductor material of the one conductivity type of relatively low resistivity in said ridges of semiconductor material;
• and
• applying conductive material to form a second electrical connection in ohmic contact with the semiconductor material of the one conductivity type of relatively low resistivity in said ridges of semiconductor material.