Abstract: A high density circuit package includes a pair of planar packages, the planar packages exhibiting front and back surfaces and positioned back-to-back in the high density circuit package. Each planar package includes a flexible circuit carrier having a plurality of circuit chips mounted thereon. Front and back planar metallic heat sinks sandwich the circuit carriers, at least one of the heat sinks contacting a surface of the chips mounted on the sandwiched circuit carriers. Each heat sink is provided with air flow apertures formed in its planar surface and adjacent to each circuit chip. A circuit card interconnects with the circuit carriers in an interconnection region and is pluggable into a female connector. The planar metallic heat sinks and circuit carriers are mechanically packaged so as to provide a planar arrangement which aligns the apertures in both the front and rear heat sinks.

Abstract: A vertical ballistic transistor is described. Base metallic contacts of reliable thickness are deposited on a carrier depletable layer and diffuse into the base. A depletion region forms in the depletable layer. The depletion region electrically isolates the base contact from the emitter. The thickness of the depletable layer prevents the generation of usual depletion regions in the base that tend to cut off base current.

Abstract: A process for the fabrication of a vertically differentiated semiconductor structure is disclosed. In this process the semiconductor structure is covered with a vertical erosion control mask. The control mask covering at least one horizontal surface of the semiconductor structure is removed leaving the vertical surface covering intact. An isotropic etching of the uncovered horizontal surface next occurs. Finally, the control mask covering of the vertical surface of the semiconductor structure is removed. This process permits etching treatment of horizontal surface defects without adverse effect on the vertical surface of the semiconductor structure.