Abstract Disclosed is an improved method for forming corrosion resistant beam lead connectors on semiconductor devices such as integrated circuits. A barrier layer of a titanium and tungsten alloy is deposited over the surface of the integrated circuit. A layer of gold is then deposited over the barrier layer. The layer of gold is patterned to define interconnection paths between the various devices of the integrated circuit and beam lead connection geometries, using photoresist and a gold etchant. The titaniumtungsten barrier layer is left intact during this step. The photoresist pattern is removed and a second pattern is applied to cover all areas of the integrated circuit except those areas where beam leads are desired. An additional layer of gold is plated to the appropriate thickness to form the beam leads, the photoresist pattern effecting a plating stop-off and the titanium-tungsten layer providing electrical continuity across the slice. Electrical separation between beam lead connectors and device interconnection paths is effected by etching the titaniumtungsten alloy with an etchant that attacks only the alloy, leaving the gold geometries intact.
The method in accordance with claim 1 wherein platinum silicide is formed in the exposed portions of the oxide mask to make good ohmic contact to the exposed circuit components prior to The step of depositing the layer of titanium:tungsten.
Claim 2
Dependent Claim
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The method in accordance with claim 2 wherein the titanium-tungsten etchant is selected from the group consisting of hydrogen peroxide, sodium peroxide, and alkali potassium fericyanide followed by hydrochloric acid.
Claim 3
Dependent Claim
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The method in accordance with claim 2 wherein said titanium: tungsten etchant is hydrogen peroxide, having a concentration in the range of from 5 to 35 percent.
Claim 4
Dependent Claim
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The method in accordance with claim 4 wherein said hydrogen peroxide has a concentration in the range of 30-35 percent.
Claim 5
Dependent Claim
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The method in accordance with claim 5 wherein said layer of titanium:tungsten is formed to a thickness in the range of 1,000-4,000 A, said first gold layer is formed to have a thickness in the range of from 3,000-10,000 A and said second layer of gold is formed to have a thickness in the range of 10,000-100,000 A.