Abstract:
A planar monolithic integrated circuit chip containing an isolation region of one conductivity type extending completely around the edge or periphery of the chip in order to insure that there are no exposed P-N junctions on an edge surface of the chip. Such an isolation region extends for at least a minimum distance from the edge of the chip, said distance being determined so as to minimize the risk of any edge defects in the chip resulting from dicing and handling from extending beyond the isolation region into the body of the chip. An insulative layer over the planar surface of the chip supports a metallization pattern for interconnecting the devices in the integrated circuit and for distributing a plurality of voltage supplys at different levels to the devices. The metallization pattern is arranged so that only metallization connected to the voltage supply at the same level as the peripheral isolation region is located on the portion of the insulative layer between the chip edge and the minimum distance of the isolation junction from the edge.
Abstract:
In the fabrication of integrated circuits, a method of forming openings through an insulative layer wherein a plurality of openings being formed through said insulative layer are subjected to two separate etching steps in order to insure that the opening is made. In the method, a layer of electrically insulative material is formed on a substrate. The layer is covered with a first photoresist mask having a plurality of openings. Then, a plurality of openings through the insulative layer coincident with the mask openings is made by applying a chemical etchant through the photoresist mask. The second photoresist mask having a plurality of openings coincident with the openings in the insulative layer is then formed on said layer; these openings in the second photoresist mask have smaller lateral dimensions than the openings in the insulative layer. Thus, the sides of the openings in the insulative layer are masked by photoresist. The chemical etchant is reapplied through the second photoresist mask. In this reapplication, any openings which may not have been fully etched through the insulative layer in the first etching step are now made. On the other hand, because the sides of completed openings are already masked by photoresist, there is no possibility of the reapplied etchant etching through the sides of such completed holes to overetch such holes.