NOR solid state circuit

Photolithographic techniques have been applied to fabrication of an NOR solid circuit containing four resistors and a transistor. The two dimensional circuit is layed out on diffused base germanium in a .1 inch square. Photographic slides of individual components are combined on a single slide by a photomicrographic camera with .25 mil indexing accuracy in X - Y directions. Several such composite slides successively expose the germanium wafer coated with photo resist. The first slide exposes for the A1 alloy-emitter bar of the transistor. A second has the pattern for the gold alloy ohmic contacts on resistors and base of transistor. A third contains the etch-moat pattern for isolating resistors and transistor. The last slide images the nickel masking plate for evaporated A1 leads interconnecting components (after a previous pattern exposes resist for an insulating layer under the leads). In summary, solid state diffusion and photolithographic techniques are combined to yield the electronic properties and topological control necessary for active and passive elements in solid state circuits on semiconductor wafers.