Abstract: A double level metal interconnection structure and process for making same are disclosed, wherein an etch-stop layer is formed on the first metal layer to prevent over-etching thereof when forming the second level metal line in a via hole in an insulating layer thereover, by means of reactive plasma etching. The etch-stop layer is composed of chromium and the reactive plasma etching is carried out with a halocarbon gas.

Abstract: A device and method are disclosed for incorporating on a single semiconductor chip, integrated injection logic (I.sup.2 L) circuits operating at low signal voltages and off chip driver devices operating at relatively high signal voltages. The vertical NPN transistor operated in an upward injection mode as is conventionally employed in I.sup.2 L circuitry, is formed with a thinner epitaxial layer between the buried subemitter and the base region than is the thicker epitaxial layer separating the buried subcollector from the base region in the downward injecting NPN vertical transistors employed as the off chip drivers and receivers on the same semiconductor chip. A method is disclosed for forming this structure which employs the technique of introducing damage in the epitaxial region above the buried subemitter of the I.sup.2 L vertical transistor so as to enhance the reactivity of the epitaxial surface to a subsequent oxidation reaction step.

Abstract: An improved merged transistor logic (I.sup.2 L) process is disclosed which provides a practical technique for forming micron to sub-micron window size devices. In a single step, the process forms all of the contact and guard ring windows in the passivation layer and then by use of selective blocking of various combinations of these windows, the various ion-implanted regions of the devices are formed with a minimum number of hot processing steps. A second embodiment of the method forms a double diffused lateral PNP device having an asymmetrically placed emitter within the base so as to enhance the injection efficiency in the vicinity of the collector. A micron to sub-micron window for the formation of all contacts and guard ring permits a merged transistor logic structure to be formed having a reduced upward NPN collector-base capacitance, lower PNP emitter-base diffusion capacitance, a lower PNP base series resistance, and an increased probability of avoiding collector-emitter pipe defects.