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Schottky-barrier Structure Employing Two Metal Alloys With Different Barrier Heights

IP.com Disclosure Number: IPCOM000061933D
Original Publication Date: 1986-Aug-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Hsieh, CM: AUTHOR [+2]

Abstract

The structure described consists of a Schottky-barrier diode (SBD) in a central area surrounded by a ring of higher-barrier metal forming another SBD in parallel electrically. The structure minimizes voids which are common in ordinary SBD processing. In addition, the wider depletion region of the high-barrier SBD acts as a guard ring to minimize fringe fields of the central SBD and minimize leakage.

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Schottky-barrier Structure Employing Two Metal Alloys With Different Barrier Heights

The structure described consists of a Schottky-barrier diode (SBD) in a central area surrounded by a ring of higher-barrier metal forming another SBD in parallel electrically. The structure minimizes voids which are common in ordinary SBD processing. In addition, the wider depletion region of the high-barrier SBD acts as a guard ring to minimize fringe fields of the central SBD and minimize leakage.

A common method of constructing an SBD starts with a silicon dioxide layer on a silicon substrate followed by a silicon nitride layer. After wet etching a hole through both layers to the substrate, the silicon nitride tends to etch with a smaller hole than the silicon dioxide underneath leaving an overhang of the nitride. Deposition by evaporation of the barrier metal through the nitride hole can leave mobile ions and other contaminants that are trapped below the overhang and on the sil surface. This condition can cause instability and excessive leakage.

The figure shows the new structure, which in the example described has an N+ buried layer 1, an N- epitaxial layer 2, a silicon dioxide layer 3 and a silicon nitride layer 4. After holes have been etched in the oxide 3 and nitride 4 layers, platinum 5 is deposited through the holes using a plasma deposition process. By this means the platinum is deposited to thickness of about 500 to 1,000 Angstroms on the exposed silicon surface and...