Forming interconnections for multilevel interconnection metallurgy systems

Claim 1

A method for making a connective system for electrically connecting regions of a semiconductor substrate, the method comprising the steps of: a. forming a patterned composite metal film at select regions of the substrate, the composite metal film being formed with a first metallic layer in contact with the substrate, a second metallic layer overlaying the first layer and a third metallic layer overlaying the second layer, the metal of the second layer having an etch rate substantially less than the etch rate of the third layer when reactive ion etched in a gas mixture including argon and chlorine; b. forming a positive patterning composition reactive ion etch mask at select regions of the composite metal film, the composite mask including a first mask layer of Novolak-resin-based photoresist of predetermined thickness overlaying the composite metal film, a second masking layer of methylsiloxane resin of predetermined thickness overlaying the first masking layer and a third masking layer of radiation sensitive material overlaying the second masking layer; c. patterning the composite etch mask by selectively exposing the third layer thereof to radiation in accordance with the pattern desired, developing the third layer, patterning the mask second layer with a reactive ion etch in a gas mixture including fluorine and oxygen in accordance with the pattern of the third layer; and thereafter patterning the mask first layer with a reactive ion etch of oxygen in accordance with the pattern of the second layer so that the second layer does not overhang the first layer; d. patterning the third metallic layer of the composite metal film by reactive ion etching with a gas mixture including argon and chlorine so that the predetermined thickness of the etch mask second and third layer sustains a residual thickness after etch which is sufficient to assure formation of a metallic stud in the third layer substantially in conformity with the mask pattern, the second metallic layer of the metal film acting as an etch stop; e. removing the residual composite reactive ion etch mask; f. depositing a nonconducting film over the patterned composite metal film and the substrate; and g. etching the nonconductive film to expose at least a portion of the stud formed in the third layer of the composite metal film.

Claim 2

A method for making a connective system for electrically connecting regions of a semiconductor substrate, the method comprising the steps of: a. forming a patterned composite metal film at select regions of the substrate, the composite metal film being formed with a first metallic layer in contact with the substrate, a second metallic layer overlaying the first layer and a third metallic layer overlaying the second layer, the metal of the second layer having an etch rate substantially less than the etch rate of the third layer when reactive ion etched in a gas mixture including argon and chlorine; b. forming a positive patterning composition reactive ion etch mask at select regions of the composite metal film, the composite mask including a first mask layer of Novolak-resin-based photoresist of predetermined thickness overlaying the composite metal film, a second masking layer of methylsiloxane resin of predetermined thickness overlaying the first masking layer and a third masking layer of radiation sensitive material overlaying the second masking layer; c. patterning the composite etch mask by selectively exposing the third layer thereof to radiation in accordance with the pattern desired, developing the third layer, patterning the mask second layer with a reactive ion etch in a gas mixture including fluorine and oxygen in accordance with the pattern of the third layer; and thereafter patterning the mask first layer with a reactive ion etch of oxygen in accordance with the pattern of the second layer so that the second layer does not overhang the first layer; d. patterning the third metallic layer of the composite metal film by reactive ion etching with a gas mixture including argon and chlorine so that the predetermined thickness of the etch mask second and third layer sustains a residual thickness after etch which is sufficient to assure formation of a metallic stud in the third layer substantially in conformity with the mask pattern, the second metallic layer of the metal film acting as an etch stop; e. removing the residual composite reactive ion etch mask; f. depositing a nonconducting film over the patterned composite metal film and the substrate; and g. etching the nonconductive film to expose at least a portion of the stud formed in the third layer of the composite metal film.