Abstract: The process employs ion implantation for precise dopant control. The implantation is performed into a thin layer of amorphous silicon covering the emitter and collector opening. The implantation energy is chosen so that the damage is confined to the amorphous layer. Since the deposited silicon layer is to be removed by subsequent processing, its thickness must be carefully controlled. The layer is preferably deposited by a sputtering technique which allows the necessary uniformity and reproducibility of the layer thickness. Furthermore, the sputtering process with its energetic ions provides a reproducible quality interface which is of critical importance for a diffusion source. With such a source, the diffusion into the single crystal silicon extends about the same distance in the horizontal as the vertical direction. This provides the greatest possible horizontal displacement of the junction under the passivating silicon dioxide layer.

Abstract: Disclosed is a method for fabricating very high performance semiconductor devices, particularly bipolar-type transistors having a heavily doped inactive base and a lightly doped narrow active base formed by ion implantation. In order to prevent the high dose boron implantation, for an NPN transistor, from getting into the active base region, a self-aligned mask covering the emitter contact i.e., active base region, is required for inactive base implantation. The self-aligned mask is anodically oxidized aluminum pads. The device wafer metallized with blanket aluminum film is immersed in a dilute H.sub.2 SO.sub.4 solution electrolytic cell which selectively anodizes only the aluminum lands situated over the Si.sub.3 N.sub.4 /SiO.sub.2 defined device contact windows. The aluminum oxide formed by anodization process is porous but may be sealed and densified. The aluminum film that is not anodized is then selectively etched off using either chemical solution or sputter etching.

Abstract: A method for making wide, deep recessed oxide isolation trenches in silicon semiconductor substrates. A semi-conductor substrate is selectively etched to produce a spaced succession of narrow, shallow trenches separated by narrow silicon mesas. Silicon oxide is chemical-vapor-deposited on the horizontal and vertical surfaces of the etched structure to a thickness equalling the width of a desired silicon oxide mask. The mask is used for etching multiple deep trenches in the substrate, the trenches being separated by thin walls of silicon. The thickness of the walls is uniformly equal to and determined by the thickness of the deposited silicon oxide mask.The deposited silicon oxide is reactively ion etched away from the horizontal surfaces, leaving the oxide only on the sidewalls of the shallow trenches. The silicon is deeply etched, using the remaining oxide as a mask.