Structure and method of forming metal interconnect structures in ultra low-k dielectrics

Abstract

A metal interconnect structure in ultra low-k dielectrics is described having a capped interconnect layer; an interconnect feature with a contact via and a contact line formed in a dielectric layer, where the via is partially embedded into the interconnect layer; and a thin film formed on the dielectric layer and separating the dielectric layer from the contact line. A method of fabricating the interconnect structure is also described and includes forming a first dielectric on a capped interconnect element; forming a thin film over the first dielectric; forming a second dielectric on the thin film; forming a via opening on the second dielectric, the thin film and extending into the first dielectric; forming a line trench on a portion of the second dielectric; and filling the via opening and the line trench with a conductive material for forming a contact via and a contact line, where the contact via is partially embedded in the interconnect element.

1 . An interconnect structure comprising:
 a capped interconnect layer;   a dielectric layer having at least one interconnect feature, said interconnect feature having a contact via and a contact line, wherein said contact via is partially embedded into a portion of said interconnect layer; and   a thin layer formed on said dielectric layer, said thin layer separating said dielectric layer from said contact line.   
     
     
         2 . The interconnect structure of  claim 1 , wherein said interconnect layer includes a metal selected from a group consisting of Cu, Al, W and alloys thereof. 
     
     
         3 . The interconnect structure of  claim 1 , wherein said dielectric layer is an ultra low-k dielectric layer. 
     
     
         4 . The interconnect structure of  claim 1 , wherein said at least one interconnect feature includes a metal selected from a group consisting of Cu, Al, W and alloys thereof. 
     
     
         5 . The interconnect structure of  claim 1 , wherein said at least one interconnect feature includes a Cu-containing conductive material. 
     
     
         6 . The interconnect structure of  claim 1 , wherein the thin layer is a metallic layer used as etch stopper to prevent a localized deep trench defect formation in said contact line. 
     
     
         7 . The interconnect structure of  claim 6 , wherein said metallic layer is selected from the group consisting of TaN, Ta, Co and W, Ti and TiN. 
     
     
         8 . The interconnect structure of  claim 1 , wherein said thin layer is a low-k dielectric material adapted as an etch stopper to prevent a localized deep trench formation in said contact line. 
     
     
         9 . The interconnect structure of  claim 1 , wherein said thin layer is selected from a group consisting of SixNy, SiCx, SiCxNyHz, NbloK, PECVD, Al2O3, Flowable Oxide, TEOS, and Polyimide. 
     
     
         10 . An interconnect structure comprising:
 an interconnect element formed on a first insulating layer and having a capping layer;   a second insulating layer formed on said capping layer, wherein said second insulating layer includes at least one interconnect feature having a metal via and a metal line,
 wherein a said metal via is perpendicular to said interconnect element and is partially embedded into a portion of said interconnect element, and 
 wherein said metal line is parallel to said interconnect element; and 
   a thin layer formed over said second insulating layer, said thin layer separating said second insulating layer from said metal line.   
     
     
         11 . The interconnect structure of  claim 10 , wherein said second insulating layer contains a dielectric material. 
     
     
         12 . The interconnect structure of  claim 11 , wherein said dielectric material is an ultra low-k dielectric. 
     
     
         13 . The interconnect structure of  claim 10 , wherein said interconnect element includes a conductive material. 
     
     
         14 . The interconnect structure of  claim 13 , wherein said conductive material is selected from a group consisting of Cu, Al, W and alloys thereof. 
     
     
         15 . The interconnect structure of  claim 13 , wherein said conductive material is Cu. 
     
     
         16 . The interconnect structure of  claim 10 , wherein an upper surface of said interconnect element is substantially coplanar with a surface of said first insulating layer. 
     
     
         17 . The interconnect structure of  claim 10 , wherein the thin layer is a metallic layer. 
     
     
         18 . The interconnect structure of  claim 17 , wherein said metallic layer is selected from the group consisting of TaN, Ta, Co and W, Ti and TiN. 
     
     
         19 . The interconnect structure of  claim 10 , wherein said thin layer is a low-k dielectric material. 
     
     
         20 . The interconnect structure of  claim 10 , wherein said thin layer is selected from a group consisting of SixNy, SiCx, SiCxNyHz, NbloK, PECVD, Al2O3, Flowable Oxide, TEOS, and Polyimide. 
     
     
         21 . An interconnect structure comprising:
 an interconnect element having a metal and formed on a first dielectric layer;   a capping layer formed on said interconnect element;   an ultra low-k dielectric layer formed on said capping layer, said ultra low-k dielectric layer having at least one interconnect feature, wherein said interconnect feature includes a first portion parallel to said dielectric layer and a second portion perpendicular to said dielectric layer, wherein said second portion is substantially embedded in a portion of said interconnect element; and   a thin layer formed on a surface of said first portion of said interconnect feature.   
     
     
         22 . The interconnect structure of  claim 21 , wherein said second portion is a conductive via line. 
     
     
         23 . The interconnect structure of  claim 21 , wherein said first portion is a conductive line. 
     
     
         24 . The interconnect structure of  claim 21 , wherein the thin layer is a metallic layer. 
     
     
         25 . The interconnect structure of  claim 24 , wherein said metallic layer is selected from the group consisting of TaN, Ta, Co and W, Ti and TiN. 
     
     
         26 . The interconnect structure of  claim 21 , wherein said thin layer is a low-k dielectric material. 
     
     
         27 . The interconnect structure of  claim 22 , wherein said thin layer is selected from a group consisting of SixNy, SiCx, SiCxNyHz, NbloK, PECVD, Al2O3, Flowable Oxide, TEOS, and Polyimide. 
     
     
         28 . A method of fabricating an interconnect structure, comprising:
 forming a capped interconnect element on an insulating layer;   forming a first dielectric layer on said capped interconnect element;   forming a thin barrier layer over said first dielectric layer;   forming a second dielectric layer on said thin barrier layer;   forming a via opening on said second dielectric layer and said thin barrier layer;   forming a line trench on a portion of said second dielectric layer, wherein said via opening extends into a portion of said first dielectric layer; and   filling said via opening and said line trench with a conductive material for forming a contact via and a contact line.
 wherein a portion of said contact via is partially embedded in a portion of said interconnect element and further wherein said thin barrier layer separates said first dielectric from said contact line. 
   
     
     
         29 . The method of fabricating the interconnect structure of  claim 28 , wherein said interconnect element includes a material selected from a group consisting of Cu, Al, W and alloys thereof. 
     
     
         30 . The method of fabricating the interconnect structure of  claim 28 , wherein said conductive material is Cu. 
     
     
         31 . The method of fabricating the interconnect structure of  claim 28 , wherein the thin barrier layer is a metallic layer. 
     
     
         32 . The method of fabricating the interconnect structure of  claim 31 , wherein said metallic layer is selected from the group consisting of TaN, Ta, Co and W, Ti and TiN. 
     
     
         33 . The method of fabricating the interconnect structure of  claim 28 , wherein said thin barrier layer is a low-k dielectric material. 
     
     
         34 . The method of fabricating the interconnect structure of  claim 28 , wherein said thin barrier layer is selected from a group consisting of SixNy, SiCx, SiCxNyHz, NbloK, PECVD, Al2O3, Flowable Oxide, TEOS, and Polyimide. 
     
     
         35 . The method of fabricating the interconnect structure of  claim 28 , wherein said first dielectric layer and said second dielectric layer are ultra low-k dielectrics. 
     
     
         36 . A method of forming an interconnect structure, the method comprising:
 forming a first ultra low-k dielectric of via height thickness on top of an underlying interconnect layer;   forming an ultra thin film on said first ultra low-k dielectric layer;   forming a second ultra low-k dielectric of line level thickness on said ultra thin film;   etching a via through said second ultra low-k dielectric, said ultra thin film and substantially through said first ultra low-k dielectric;   etching a line trench in a portion of said second ultra low-k dielectric, wherein said via is etched through said interconnect layer; and   depositing a metal for defining an interconnect level.   
     
     
         37 . The method of forming the interconnect structure of  claim 36 , wherein said interconnect layer includes a Cu containing material. 
     
     
         38 . The method of forming the interconnect structure of  claim 36 , wherein the ultra thin film is a metallic layer. 
     
     
         39 . The method of forming the interconnect structure of  claim 38 , wherein said metallic layer is selected from the group consisting of TaN, Ta, Co and W, Ti and TiN. 
     
     
         40 . The method of forming the interconnect structure of  claim 36 , wherein said ultra thin film is a low-k dielectric material. 
     
     
         41 . The method of forming the interconnect structure of  claim 36 , wherein said ultra thin film is selected from a group consisting of SixNy, SiCx, SiCxNyHz, NbloK, PECVD, Al2O3, Flowable Oxide, TEOS, and Polyimide. 
     
     
         42 . The method of forming the interconnect structure of  claim 36 , wherein said interconnect level includes a contact via and a contact line. 
     
     
         43 . The method of forming the interconnect structure of  claim 42 , wherein said contact via is partially embedded in a portion of said interconnect layer and wherein said ultra thin firm is formed between a surface of said contact line and said first ultra low-k dielectric.