US 11,990,414 B2
BEOL alternative metal interconnects: integration and process
Chih-Chao Yang, Glenmont, NY (US); and Theo Standaert, Clifton Park, NY (US)
Assigned to International Business Machines Corporation, Armonk, NY (US)
Filed by International Business Machines Corporation, Armonk, NY (US)
Filed on Dec. 8, 2020, as Appl. No. 17/115,160.
Application 17/115,160 is a division of application No. 15/912,089, filed on Mar. 5, 2018, granted, now 10,886,225.
Prior Publication US 2021/0091010 A1, Mar. 25, 2021
Int. Cl. H01L 23/48 (2006.01); H01L 21/768 (2006.01); H01L 23/522 (2006.01); H01L 23/525 (2006.01); H01L 23/532 (2006.01)
CPC H01L 23/53252 (2013.01) [H01L 21/76807 (2013.01); H01L 21/76843 (2013.01); H01L 21/76864 (2013.01); H01L 23/5226 (2013.01); H01L 23/5256 (2013.01); H01L 23/53238 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A back-end-of-the line (BEOL) interconnect structure comprising:
a first metal structure composed of a noble metal and present in a combined via/line opening of an interconnect dielectric material layer, wherein the noble metal is selected from the group consisting of rhodium (Rh), palladium (Pd), silver (Ag), osmium (Os), iridium (Ir), platinum (Pt) and gold (Au);
a second metal structure composed of a metal that is less noble than the noble metal present in an upper portion of the combined via/line opening and in direct physical contact with the first metal structure, wherein the metal that provides the second metal structure is selected from the group consisting of copper (Cu), cobalt (Co), tantalum (Ta), titanium (Ti), aluminum (Al) and tungsten (W), and a portion of the first metal structure is located on each sidewall surface of the second metal structure;
a selective metal cap having a different metal composition than the second metal structure located entirely on the second metal structure, wherein the selective metal cap has an outermost sidewall that is vertically aligned with an outermost sidewall of the second metal structure; and
an upper dielectric capping layer located on the interconnect dielectric material layer and a portion of the first metal structure, wherein a lower portion of the upper dielectric capping layer embeds the selective metal cap.