Electrically conductive interconnect system and method

Abstract

An electrically conductive interconnect system has a post, extending above a supporting surface, the post including a rigid material, a coating on the rigid material, wherein the post and has a first width at the supporting surface and a second width at a distance removed from the supporting surface, and the post narrows from the first width to the second width. A method of electrically connecting a portion of a first supporting surface to a portion of a second supporting surface involves bringing a post on the first supporting surface into contact with an electrically conductive material located on the second supporting surface, softening the electrically conductive material, causing a separation distance between the first supporting surface and the second supporting distance to decrease so that a portion of the post will be surrounded by the electrically conductive material, and allowing the temperature of the electrically conductive material to decrease.

1 . A method of forming an electrical connection, the method comprising:
 contacting a post on a first supporting surface of a first integrated circuit chip with an electrically-conductive material on a second supporting surface of a second integrated circuit chip;   heating the electrically-conductive material to soften the electrically-conductive material;   surrounding a portion of the post with the softened electrically-conductive material; and   cooling the electrically-conductive material.   
     
     
         2 . The method of  claim 1 , wherein the post comprises a rigid material that is less malleable than the electrically-conductive material. 
     
     
         3 . The method of  claim 2 , wherein the rigid material comprises copper. 
     
     
         4 . The method of  claim 2 , further comprising applying a first electrically-conductive coating to the rigid material. 
     
     
         5 . The method of  claim 4 , wherein the first electrically-conductive coating comprises nickel. 
     
     
         6 . The method of  claim 4 , further comprising applying a second electrically-conductive coating to the first electrically-conductive coating. 
     
     
         7 . The method of  claim 6 , wherein the electrically-conductive material is different from the second electrically-conductive coating. 
     
     
         8 . The method of  claim 6 , wherein the second electrically-conductive coating comprises gold. 
     
     
         9 . The method of  claim 1 , wherein said heating the electrically-conductive material comprises heating the electrically-conductive material to a temperature between about 240° C. and about 270° C. 
     
     
         10 . The method of  claim 1 , wherein the post is one of a plurality of posts on the first supporting surface. 
     
     
         11 . The method of  claim 10 , wherein the post is spaced apart from an adjacent post by a distance of 50 μm or less. 
     
     
         12 . The method of  claim 1 , wherein the first supporting surface comprises an electrically-conductive pad. 
     
     
         13 . The method of  claim 1 , wherein the post has a first portion having a first width at the first supporting surface and a second portion having a second width at a distance from the first supporting surface, and wherein the second width is less than the first width. 
     
     
         14 . The method of  claim 13 , wherein the first width is larger than a height of the post. 
     
     
         15 . The method of  claim 13 , wherein the first width is smaller than a height of the post. 
     
     
         16 . The method of  claim 13 , wherein the post further comprises a third portion having a third width located between the first portion and the second portion, and wherein the third width is greater than the first and second widths. 
     
     
         17 . The method of  claim 1 , wherein the post comprises at least one lateral extension, and wherein the lateral extension increases a lateral surface area of the post. 
     
     
         18 . The method of  claim 1 , wherein, after said surrounding, the first and second supporting surfaces are separated by a distance less than the sum of a height of the post and a height of the electrically-conductive material prior to said contacting. 
     
     
         19 . A method of forming an electrical connection, the method comprising:
 contacting a post on a first supporting surface of a first integrated circuit chip with an electrically-conductive material on a second supporting surface of a second integrated circuit chip;   heating the electrically-conductive material to soften the electrically-conductive material;   aligning the post and the electrically-conductive material;   decreasing a separation distance between the first and second supporting surfaces, thereby surrounding a portion of the post with the softened electrically-conductive material; and   cooling the electrically-conductive material to create an electrical connection between the post and the electrically-conductive material.   
     
     
         20 . The method of  claim 19 , wherein the post comprises a rigid material that is less malleable than the electrically-conductive material. 
     
     
         21 . The method of  claim 20 , further comprising applying a first electrically-conductive coating to the rigid material. 
     
     
         22 . The method of  claim 21 , further comprising applying a second electrically-conductive coating to the first electrically-conductive coating. 
     
     
         23 . The method of  claim 19 , wherein said heating the electrically-conductive material comprises heating the electrically-conductive material to a temperature between about 240° C. and about 270° C. 
     
     
         24 . The method of  claim 19 , wherein the electrically-conductive material comprises a gold-tin alloy, a silver-tin alloy, or a lead-tin alloy. 
     
     
         25 . The method of  claim 19 , further comprising thinning the first supporting surface. 
     
     
         26 . The method of  claim 19 , wherein the post is one of a plurality of posts on the first supporting surface, and wherein the post is spaced apart from an adjacent post by a distance of 50 μm or less. 
     
     
         27 . The method of  claim 19 , wherein the post has a first portion having a first width at the first supporting surface and a second portion having a second width at a distance from the first supporting surface, and wherein the second width is less than the first width. 
     
     
         28 . The method of  claim 27 , wherein the post further comprises a third portion having a third width located between the first portion and the second portion, and wherein the third width is greater than the first and second widths.