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Forming Low Metal to Metal Contact Resistance in Multilevel Metallization on Integrated Circuit Semiconductor Devices

IP.com Disclosure Number: IPCOM000085773D
Original Publication Date: 1976-Jun-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Hildick, WK: AUTHOR

Abstract

Semiconductor devices having two or more layers of contact metallurgy having separating insulating layers require low-resistance contact areas between layers. Contact areas are accomplished by etching via holes in the insulating layer prior to the deposition or formation of the second level of metallurgy.

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Forming Low Metal to Metal Contact Resistance in Multilevel Metallization on Integrated Circuit Semiconductor Devices

Semiconductor devices having two or more layers of contact metallurgy having separating insulating layers require low-resistance contact areas between layers. Contact areas are accomplished by etching via holes in the insulating layer prior to the deposition or formation of the second level of metallurgy.

Especially where aluminum and aluminum alloys are used for the first level of metallurgy, a zinc coating of the clean metal surface in vias accomplishes the aforesaid result.

The method comprises first cleaning the aluminum metal, using any conventional method to remove contaminants and oxide formed on the surface of the metal. Sputter cleaning, chemical reactive cleaning and plasma cleaning are examples of techniques to be used.

After via holes are etched in the wafers, the above cleaning step is undertaken utilizing proper rinsing procedures well known in the art.

The zinc immersion then immediately follows by dipping, or other suitable techniques, the wafers in a solution of zinc sulfate/hydrofluric acid at room temperature.

An example of this solution is an aqueous mixture of: a) 5.0N ZnSO(4) 7 H(2)O (718.9 grams per liter), and b) 1.0N HF (35 ml/1 - 48% acid).

The immersion should be approximately 20 seconds followed by an overflow water rinse for about 5 minutes.

Wafers are then heated to approximately 200-250 degrees C and the desired meta...