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Fabrication of Tunnel Diodes

IP.com Disclosure Number: IPCOM000096525D
Original Publication Date: 1963-Jul-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Logan, JS: AUTHOR

Abstract

For optimum performance at high-switching speeds, the size of the PN junction of a tunnel diode must be very small. This means that the cross-sectional dimensions or diameter of the junction must be but a few microns for values of peak current of 100 milliamperes or less. Since most tunnel diodes today are made by alloying to assure the necessary abrupt junction, an etching operation is then required to reduce the size of the junction to the particular dimensions needed for establishing the desired or rated peak current. In reducing the diameter of the junction to a few microns, it is necessary to provide adequate mechanical support for the semiconductor material about the junction.

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Fabrication of Tunnel Diodes

For optimum performance at high-switching speeds, the size of the PN junction of a tunnel diode must be very small. This means that the cross- sectional dimensions or diameter of the junction must be but a few microns for values of peak current of 100 milliamperes or less. Since most tunnel diodes today are made by alloying to assure the necessary abrupt junction, an etching operation is then required to reduce the size of the junction to the particular dimensions needed for establishing the desired or rated peak current. In reducing the diameter of the junction to a few microns, it is necessary to provide adequate mechanical support for the semiconductor material about the junction.

This fabrication technique permits the tunnel diode to be made by an alloying operation. It makes it unnecessary to perform any etching for reducing the diameter of the junction to establish the rated peak current for the device. It provides adequate mechanical support for the resulting junction.

Thin impervious insulating film 10 of a material such as silicon dioxide is deposited on a degeneratively doped starting wafer 11 of semiconductor material of one conductivity type by techniques such as the thermal decomposition of an organo-oxy-silane. Using a known etch-resistant mask and procedures, two small holes 12 and 13 having a predetermined diameter are etched in film 10. Then alloy material 14 comprising a carrier metal and an impurity of a conductivity-directing type opposite to that in wafer 11 is deposited in aperture 12 and over a small area of the film about the aperture.

Then, the unit is introd...