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Composite Monocrystalline Semiconductor Resistor

IP.com Disclosure Number: IPCOM000096986D
Original Publication Date: 1962-Mar-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Marinace, JC: AUTHOR

Abstract

Resistors for microelectronic circuits are conventionally made by vacuum evaporation of a metal through a carefully dimensioned mask onto a very high resistivity substrate. The mask provides control of the length and the width dimensions. However, the thickness dimension is controlled only by the deposition rate of the metal and the duration of the deposition. These latter two variables are not easy to control, especially for high values of resistance, because of the non-continuity of very thin films. An improvement is effected by depositing into a shallow depression and then removing the excess metal to the level of the lands. However, the high conductivity of metals would require that a very carefully controlled, very shallow depression be made. No technology known today permits this.

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Composite Monocrystalline Semiconductor Resistor

Resistors for microelectronic circuits are conventionally made by vacuum evaporation of a metal through a carefully dimensioned mask onto a very high resistivity substrate. The mask provides control of the length and the width dimensions. However, the thickness dimension is controlled only by the deposition rate of the metal and the duration of the deposition. These latter two variables are not easy to control, especially for high values of resistance, because of the non-continuity of very thin films. An improvement is effected by depositing into a shallow depression and then removing the excess metal to the level of the lands. However, the high conductivity of metals would require that a very carefully controlled, very shallow depression be made. No technology known today permits this.

The substitution of a degenerately doped semiconductor, having a small temperature coefficient of resistance, overcomes this difficulty. This is by virtue of the fact that the conductivity of a degenerate semiconductor is approximately
0.001 that of metals. However, vacuumevaporated semiconductors are notorious in their lack of reproducibility of electrical properties because of their polycrystallinity.

Epitaxial monocrystalline degenerate semiconductors are grown by a vapor- growth technique, or some other technique, on unmasked regions of, or in depressions in, monocrystalline, high-resistivity substrates of the same material or e...