| abstract |
A method is provided for creating self-aligned integrated circuit structures using the different oxidation characteristics of lightly doped and heavily doped semiconductor material. By forming heavily doped polycrystalline silicon on the surface of a lightly doped silicon epitaxial layer, and then oxidizing the resulting structure, a thin layer of oxide will be created on the lightly doped epitaxial layer and a thicker layer of oxide on the heavily doped polycrystalline silicon. The structure may then be uniformly etched to remove the oxide from the substrate, but not from the polycrystalline silicon. Impurities are then introduced into the substrate between the regions of polycrystalline silicon and from the regions of polycrystalline silicon to create desired regions in the substrate. The invention is useful for producing more compact transistor structures, and in particular, for producing integrated injection logic structures in which fewer processing steps are needed than in prior art structures. |