Abstract of the Disclosure

A monolithic integrated circuit structure is provided comprising first and second monocrystalline epitaxial semiconductor layers of a first conductivity type on a monocrystalline substrate of opposite conductivity type. Electrically isolated device regions are provided by a deep diffusion pattern extending through both epitaxial layers and having the same conductivity type as the substrate. A suitable technique for the fabrication of the structure of the invention includes the step of depositing the first epitaxial layer on a substrate surface crystallographically oriented at a small angle from the (111) plane.

• Figure 1 is a pictorial view in section of a semiconductor integrated circuit of the double epitaxy type which may be fabricated in accordance with the principles of this invention.
• Figure 2 is a schematic diagram of the NOR logic circuit embodied in the device of Figure 1.
• Figure 3 is an elevational view in section taken along the lines 3-3 in Figure 1.
• Figures 4 through 10 are schematic sectional views in elevation illustrating sequential steps in forming a wafer having a single epitaxial layer overlying a substrate with a single simple diffusion region in it.
• Figure 11 is an analogous view to Figure 10 and illustrates structure formed by the same steps as used in forming the structure of Figure 10, except that the substrate face is prepared to lie at a critical angle with the (111) plane, in accordance with the present invention.

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