Abstract of the Disclosure

Semiconductor devices are made by a modified planar process which permits ohmic contacts to be made to smaller geometries than heretofore possible. A semiconductor mesa structure is surrounded with an insulating layer having an exposed surface coplanar with the exposed surface of the mesa. The desired PN junction geometry is then formed in the mesa by selective diffusion, followed by metallization to provide ohmic contacts that extend beyond the periphery of the mesa, since the smallest contact geometry provided by the state of the art is too large to be accommodated wholly within such periphery.

• Figures 1a-1e are sectional views of a portion of a semiconductor substrate illustrating one embodiment of the mesa fabrication according to the invention.

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3,304,595  02/1967  Sato
3,345,222  10/1967  Nomura
2,972,092  02/1961  Nelson