Alternate pad structures/passivation integration schemes to reduce or eliminate imc cracking in post wire bonded dies during cu/low-k beol processing

Abstract

Passivation integration schemes and pad structures to reduce the stress gradients and/or improve the contact surface existing between the Al in the pad and the gold wire bond. One of the pad structures provides a plurality of recessed pad areas which are formed in a single aluminum pad. An oxide mesa can he provided under the aluminum pad. Another pad structure provides a single recessed pad area which is formed in a single aluminum pad, and the aluminum pad is disposed above a copper pad and a plurality of trench/via pads. Still another pad structure provides a single recessed pad area which is formed in a single aluminum pad, and the aluminum pad is disposed above a portion of a copper pad, such that the aluminum pad and the copper pad are staggered relative to each other.

What is claimed is: 
     
         1 . A pad structure comprising: a copper pad; a single aluminum pad above the copper pad; at least one recessed pad area formed in the aluminum pad, said aluminum pad being disposed above trench/via pads which are disposed proximate the copper pad; a first layer along an entire bottom surface of the aluminum pad and in contact with a top surface of each trench/via pad; and a second layer along an entire top surface of the copper pad and in contact with both the trench/via pads and portions of the first layer. 
     
     
         2 . A pad structure comprising: at least one copper pad; an aluminum pad above the copper pad; at least one recessed pad area formed in the aluminum pad, wherein the copper pad and the aluminum pad are staggered relative to each other; a first layer along an entire bottom surface of the aluminum pad and in contact with a top surface of each recessed pad area; and a second layer along an entire top surface of the copper pad and in contact with both the recessed pad areas and portions of the first layer. 
     
     
         3 . A pad structure as recited in  claim 2 , wherein the aluminum pad is above a single copper pad, as opposed to a plurality of copper pads being disposed below the aluminum pad. 
     
     
         4 . A passivation scheme for forming a pad structure which includes at least one copper pad, an aluminum pad above the copper pad, and a plurality of recessed pad areas formed in the aluminum pad, said passivation scheme comprising: providing a multiple-layer stack which includes the copper pad and a dielectric layer above the copper pad; masking the stack; etching the stack such that a plurality of slots are formed in the dielectric layer, above the copper pad; depositing aluminum in the slots; and masking and etching the stack to form a plurality of recessed pad areas in the aluminum, wherein the pad structure comprises at least one copper pad; an aluminum pad above the copper pad; at least one recessed pad area formed in the aluminum pad, wherein the copper pad and the aluminum pad are staggered relative to each other; a first layer along an entire bottom surface of the aluminum pad and in contact with a top surface of each recessed pad area; and a second layer along an entire top surface of the copper pad and in contact with both the recessed pad areas and portions of the first layer. 
     
     
         5 . A passivation scheme as recited in  claim 4 , further comprising forming and oxide mesa between the copper pad and the aluminum pad, wherein the oxide mesa is disposed between two of the recessed pad areas formed in the aluminum pad. 
     
     
         6 . A passivation scheme as recited in  claim 4 , further comprising providing a dielectric layer between the copper pad and the aluminum pad, wherein the dielectric layer is disposed between two of the recessed pad areas formed in the aluminum pad. 
     
     
         7 . A passivation scheme as recited in  claim 4 , further comprising providing that the aluminum pad is above a single copper pad, as opposed to a plurality of copper pads being disposed below the aluminum pad. 
     
     
         8 . A passivation scheme for forming a pad structure which includes an oxide mesa, a single aluminum pad above the oxide mesa, trench/via pads disposed proximate the oxide mesa, and at least one recessed pad area formed in the aluminum pad, said passivation scheme comprising: providing a multiple-layer stack which includes the oxide mesa, the trench/via pads disposed proximate the copper pad, and a dielectric layer above, the oxide mesa; masking the stack; etching the stack such that at least one slot is formed in the dielectric layer, above the oxide mesa; depositing aluminum in the at least one slot; and masking and etching the stack to form at least one recessed pad area in the aluminum, Wherein the pad structure comprises a copper pad; a single aluminum pad above the copper pad; at least one recessed pad area formed in the aluminum pad, said aluminum pad being disposed above trench/via pads which are disposed proximate the copper pad; a first layer along an entire bottom surface of the aluminum pad and in contact with a top surface of each trench/via pad; and a second layer along an entire top surface of the copper pad and in contact with both the trench/via pads and portions of the first layer. 
     
     
         9 . A passivation scheme for forming a pad structure which includes at least one copper pad; an aluminum pad above the copper pad, and at least one recessed pad area formed in the aluminum pad, wherein the copper pad and the aluminum pad are staggered relative to each other, said passivation scheme comprising: providing a multiple-layer stack which includes the copper pad and a dielectric layer above the copper pad; masking the stack; etching the stack such that at least one slot is formed in the dielectric layer, above the copper pad; depositing aluminum in the at least one slot; and masking and etching the stack to form at least one recessed pad area in the aluminum, wherein the pad structure comprises at least one copper pad; an aluminum pad above the copper pad; at least one recessed pad area formed in the aluminum pad, wherein the copper pad and the aluminum pad are staggered relative to each other; a first layer along an entire bottom surface of the aluminum pad and in contact with a top surface of each recessed pad area; and a second layer along an entire top surface of the copper pad and in contact with both the recessed pad areas and portions of the first layer. 
     
     
         10 . A passivation scheme as recited in  claim 9 , further comprising providing that the aluminum pad is above a single copper pad, as opposed to a plurality of copper pads being disposed below the aluminum pad. 
     
     
         11 . A pad structure as recited in  claim 1 , further comprising an oxide mesa disposed between two of the trench/via pads and being disposed under the single recessed pad area.