Investigation of gate arrays or semi-customized LSI

The concept of prediffused networks has its origin in the fact that the synthesis of all logic schemes begin with a simple type of operator, a logic gate. A number of operators which are not interconnected can be constructed on the same silicon platelet. This platelet can then be used to produce a large variety of circuits by interconnecting on demand the gates of the networks thus constituted. This interconnection requires a supplementary metallic layer. The advantages of this principle are that the circuits thus constituted have only known operators. The action of the masks, relative to diffusion operations common to all circuits, are designed and constructed from the beginning. Since all the circuits are constructed from identical silicon platelets, the platelets can be diffused in advance, even before the interconnection scheme is defined. The mask of the prediffused nets appears as an imprinted microcircuit which interconnects components already etched in the silicon. Existing products having this technology are described.