Laser-programmable interconnect of integrated circuit chips

Abstract

A method for producing an interconnect from a first metal trace, through a dielectric, to a second metal trace. The method comprises the steps of heating a portion of the first metal trace to cause thermal expansion and at least partial melting thereof and heating a portion of the second metal trace to cause thermal expansion and at least partial melting thereof such that the thermal expansion of the traces causes at least one crack or fissure in the dielectric to be formed between the traces and such that the melting of the traces causes the metals to fuse together through the crack or fissure, thereby producing the interconnect from the first metal trace to the second metal trace. One of the metal traces may comprise a substantially square donut shape configuration having four interior edges portions, wherein the probability of a successful interconnection is increased due to the increased number of edges present on the tope layer from which a crack or fissure to the lower layer can form.

What is claimed is:  
     
         1 . A method for producing an interconnect from a first metal trace, through a dielectric, to a second metal trace, comprising the steps of heating a portion of the first metal trace to cause thermal expansion thereof and at least partial melting of metal constituting the portion of the first metal trace and heating a portion of the second metal trace to cause thermal expansion thereof and at least partial melting of metal constituting the portion of the second metal trace such that the thermal expansion of the portions causes at least one crack in the dielectric to be formed between the portion of the first metal trace and the portion of the second metal trace and such that the melting of the metals of the portions of the first metal trace and the second metal trace causes the metals to fuse together through the crack, thereby producing the interconnect from the first metal trace to the second metal trace.  
     
     
         2 . The method as set forth in  claim 1 , wherein the portion of the first metal trace comprises an edge portion of the first metal trace that overlaps the portion of the second metal trace.  
     
     
         3 . The method as set forth in  claim 2 , wherein the steps of heating the portions of the metal traces to cause thermal expansion thereof occur simultaneously.  
     
     
         4 . The method as set forth in  claim 3 , wherein the steps of simultaneously heating the portions of the metal traces comprises the step of projecting at least one beam of electromagnetic energy simultaneously onto the edge portion of the first metal trace and onto the portion of the second metal trace.  
     
     
         5 . The method as set forth in  claim 4 , wherein the step of projecting at least one beam of electromagnetic energy comprises the step of projecting a single beam of electromagnetic energy such that a portion of the beam is projected onto the edge portion of the first metal trace and another portion of the beam is projected onto the portion of the second metal trace.  
     
     
         6 . The method as set forth in  claim 4 , wherein the beam comprises a beam of a single duration.  
     
     
         7 . The method as set forth in  claim 4 , wherein the beam comprises a beam of multiple durations.  
     
     
         8 . The method as set forth in  claim 1 , wherein the first metal trace is positioned above the second metal trace.  
     
     
         9 . The method as set forth in  claim 8 , wherein the metal of the first metal trace flows downwardly at least partially into the crack toward the second metal trace.  
     
     
         10 . The method as set forth in  claim 8 , wherein the metal of the second metal trace flows upwardly at least partially into the crack toward the first metal trace.  
     
     
         11 . The method as set forth in  claim 1 , wherein the first metal trace comprises, in part, a substantially square donut shape configuration defining four interior edge portions and wherein the portion of the first metal trace comprises the four interior edge portions.  
     
     
         12 . The method as set forth in  claim 11 , wherein the steps of heating the portions of the metal traces to cause thermal expansion thereof occur simultaneously.  
     
     
         13 . The method as set forth in  claim 12 , wherein the steps of simultaneously heating the portions of the metal traces comprise the step of projecting at least one beam of electromagnetic energy simultaneously onto the four interior edge portions of the first metal trace and onto the portion of the second metal trace.  
     
     
         14 . The method as set forth in  claim 1 , wherein a plurality of the portions of the metal traces are successively heated.  
     
     
         15 . An interconnect, comprising in combination: 
 adjacent first metal trace, dielectric and second metal trace;    means for heating a portion of the first metal trace to cause thermal expansion thereof and at least partial melting of metal constituting the portion of the first metal trace; and    means for heating a portion of the second metal trace to cause thermal expansion thereof and at least partial melting of metal constituting the portion of the second metal trace,    whereby the thermal expansion of the portions causes at least one crack in the dielectric to be formed between the portion of the first metal trace and the portion of the second metal trace and such that the melting of the metals of the portions of the first metal trace and the second metal trace causes the metals to fuse together through the crack, thereby producing the interconnect from the first metal trace to the second metal trace.    
     
     
         16 . The interconnect as set forth in  claim 15 , wherein the portion of the first metal trace comprises an edge portion of the first metal trace that overlaps the portion of the second metal trace.  
     
     
         17 . The interconnect as set forth in  claim 16 , wherein the means for heating the portions of the metal traces to cause thermal expansion thereof occur simultaneously.  
     
     
         18 . The interconnect as set forth in  claim 18 , wherein the means for simultaneously heating the portions of the metal traces comprises means for projecting at least one beam of electromagnetic energy simultaneously onto the edge portion of the first metal trace and onto the portion of the second metal trace.  
     
     
         19 . The interconnect as set forth in  claim 17 , wherein the means for projecting at least one beam of electromagnetic energy comprises means for projecting a single beam of electromagnetic energy such that a portion of the beam is projected onto the edge portion of the first metal trace and another portion of the beam is projected onto the portion of the second metal trace.  
     
     
         20 . The interconnect as set forth in  claim 18 , wherein the beam comprises a beam of a single duration.  
     
     
         21 . The interconnect as set forth in  claim 18 , wherein the beam comprises a beam of multiple durations.  
     
     
         22 . The interconnect as set forth in  claim 15 , wherein the first metal trace is positioned above the second metal trace.  
     
     
         23 . The interconnect as set forth in  claim 22 , wherein the metal of the first metal trace flows downwardly at least partially into the crack toward the second metal trace.  
     
     
         24 . The interconnect as set forth in  claim 22 , wherein the metal of the second metal trace flows upwardly at least partially into the crack toward the first metal trace.  
     
     
         25 . The interconnect as set forth in  claim 15 , wherein the first metal trace comprises, in part, a substantially square donut shape configuration defining four interior edge portions and wherein the portion of the first metal trace comprises the four interior edge portions.  
     
     
         26 . The interconnect as set forth in  claim 25 , wherein the means for heating the portions of the metal traces to cause thermal expansion thereof occur simultaneously.  
     
     
         27 . The interconnect as set forth in  claim 26 , wherein the means for simultaneously heating the portions of the metal traces comprises means for projecting at least one beam of electromagnetic energy simultaneously onto the four interior edge portions of the first metal trace and onto the portion of the second metal trace.  
     
     
         28 . The interconnect as set forth in  claim 15 , wherein a plurality of the portions of the metal traces are successively heated.