Advanced device assembly structures and methods

Abstract

A microelectronic assembly includes a first substrate having a surface and a first conductive element and a second substrate having a surface and a second conductive element. The assembly further includes an electrically conductive alloy mass joined to the first and second conductive elements. First and second materials of the alloy mass each have a melting point lower than a melting point of the alloy. A concentration of the first material varies in concentration from a relatively higher amount at a location disposed toward the first conductive element to a relatively lower amount toward the second conductive element, and a concentration of the second material varies in concentration from a relatively higher amount at a location disposed toward the second conductive element to a relatively lower amount toward the first conductive element.

1 . A method for making a microelectronic assembly, including:
 aligning a first bond component with a second bond component such that the first and second bond components are in contact with each other, the first bond component being included in a first element having a substrate defining a surface and a first conductive element at the surface, the first bond component including a first material layer adjacent the first conductive element and a first protective layer overlying the first material layer, the second bond component being included in a second element including a substrate defining a surface and a second conductive element exposed at the surface, the second bond component including a second material layer adjacent the second conductive element and a second protective layer overlying the first material layer; and   heating the first and second bond components such that at least portions of the first and second material layers diffuse together to form an alloy mass joining the first and second elements with one another.   
     
     
         2 . The method of  claim 1 , wherein the heating step is carried out at a first temperature, and wherein the alloy mass has a melting point at a second temperature greater than the first temperature. 
     
     
         3 . The method of  claim 1 , wherein the first and second protective layers diffuse together and with the first and second material layers during the step of heating to further form the alloy mass. 
     
     
         4 . The method of  claim 1 , wherein the first material layer includes at least one material component not present in the second material layer before heating. 
     
     
         5 . The method of  claim 1 , wherein the first material layer and the second material layer have lower melting points than an alloy formed with the materials from the first and second material layers and the first and second protective layers. 
     
     
         6 . The method of  claim 5 , wherein the first material is a different material than the second material and the first and second materials include materials at least one of tin, indium, or gallium. 
     
     
         7 . The method of  claim 6 , wherein the first protective layer includes copper, and wherein the second protective layer includes at least one of copper, nickel, tungsten, cobalt, phosphorous, palladium, boron, gold, or silver. 
     
     
         8 . The method of  claim 1 , wherein the first conductive element includes a bulk conductor layer and a seed layer that overlies the bulk conductor layer, the first bond component being joined to the seed layer. 
     
     
         9 . The method of  claim 8 , wherein a portion of the first material layer diffuses into the bulk conductor layer during heating. 
     
     
         10 . The method of  claim 8 , further comprising providing a barrier layer between the bulk conductor layer and the seed layer, the barrier layer preventing the first material from diffusing into the bulk conductor layer during the heating step. 
     
     
         11 . The method of  claim 1 , wherein the first substrate is a first support material layer defining the surface of the first element, and wherein the first conductive element is a metalized via extending through a portion of the first support material layer, the method further including forming the first bond component over the metalized via by depositing the first material layer within an opening of a resist layer that overlies the surface of the first element, the opening being aligned with the metalized via. 
     
     
         12 . The method of  claim 11 , wherein the step of forming the first bond component further includes depositing the first protective layer within the resist layer opening. 
     
     
         13 . The method of  claim 11 , further comprising:
 positioning a seed layer between the surface of the first element and the resist layer prior to depositing the first material layer within the opening and further overlies the end surface of the metalized via,   depositing the first material layer over the seed layer within the opening, and   removing the resist layer and portions of the seed layer that are uncovered by the first material layer.   
     
     
         14 . The method of  claim 1 , wherein the first substrate is a first support material layer defining the surface of the first element, and wherein the first conductive element is within an opening within the first support material layer, an end surface of the first conductive element and the first bond component being recessed within the opening, and wherein the step of aligning the first bond component with the second bond component includes positioning the second bond component within the opening of the first support material layer. 
     
     
         15 . The method of  claim 1 , wherein the first substrate is a first support material layer defining the surface of the first element, and wherein the first conductive element is within an opening of the first support material layer opening, an end surface of the first conductive element and the first bond component being recessed within the opening such that an outer surface of the first protective layer is substantially co-planar with the surface of the first support material layer. 
     
     
         16 . A method for making a microelectronic assembly, including:
 aligning a first bond component exposed at a surface of a first element with a second bond component exposed at a surface of a second element such that the first and second bond components are in contact with each other, each of the first and second elements including a substrate, the first bond component including a first material layer and a first protective layer overlying the first material layer, and the second bond component including a second material layer and a second protective layer overlying the second material layer; and   heating the first and second bond components such that at least the first and second material layers diffuse together to form an alloy mass joining the first and second elements with one another, the alloy mass having a melting point higher than melting points of the first and second material layers prior to heating.   
     
     
         17 . The method of  claim 16 , wherein the first and second protective layers diffuse together and with the first and second material layers during the step of heating to further form the alloy mass. 
     
     
         18 . The method of  claim 16 , wherein the first bond component surrounds an area of the surface of the first element, wherein the second bond component surrounds an area of the surface of the second element, and wherein aligning the first bond component with the second bond component defines a volume within the first bond component, the second bond component, and the surrounded portions of the surfaces of the first and second elements. 
     
     
         19 . The method of  claim 18 , wherein the step of heating further causes the internal volume to become hermetically sealed by the conductive alloy mass. 
     
     
         20 . The method of  claim 16 , wherein the first and second elements respectively include first and second conductive elements that define portions of the surface of the first and second elements to which the bond components are joined, and wherein the step of heating joins the alloy mass between the first and second conductive elements.