Electroless Plating of Copper on Metal-Nitride Diffusion Barriers Initiated by Displacement Plating

Abstract

Copper is deposited on TaN and WN barrier layers by electroless plating without the need for activation preprocessing when substrates are ͑i͒ pretreated by wet chemical etching to remove surface oxides, and ͑ii͒ immersed in an electroless Cu plating solution containing glyoxylic acid as a reducing agent. Electrical potential measurements indicate that the redox potentials of TaN and WN in the plating solution are lower than that of copper, driving displacement plating of Cu in the initial stage of deposition. The adhesion between electroless-plated Cu and the TaN barrier layer after annealing is 0.11 kgf/cm as determined by a peeling test, which is sufficient for reliability during chemical mechanical polishing. A damascene Cu interconnect was successfully fabricated without delamination and exhibited an electrical resistivity of 2.2 ⍀ cm after annealing for a 0.42 m wide interconnect track. These results indicate that the proposed electroless process is suitable for the formation of a Cu seed layer prior to electrodeposition for the fabrication of ultralarge scale integrated interconnects.

One-step electroless deposition of Pd/Pt bimetallic microstructures by galvanic replacement on copper substrate and investigation of its performance for the hydrogen evolution reaction

“…Recently, it has been proved that this simple and spontaneous process is an attractive approach for the growth of structures directly on metal or semiconductor substrates such as deposition of Au on Si [2], Ag/Pd on Si [3], Cu on Si [4], Pt on Ti [5], Au on Ge [6], Pt on Ge [7], Cu on TaN [8], Cu on Al [9], Zn on Al [10], Ni on Al [11], Pd on Ag [12], Pt/Au on Cu [13], Au on Cu [14], Ag on Cu [15] and Au on Ag [16] and other combinations.…”

Bottom-up fill mechanisms of electroless copper plating with addition of mercapto alkyl carboxylic acid

“…Consequently, copper electroless plating and chemical vapor deposition ͑CVD͒ are the most promising processes for the formation of a seed layer for electroplating. [5][6][7][8][9] Bottom-up filling of submicrometer features by iodine-catalyzed CVD was reported by Shim et al, 5 Pyo et al,and Josell et al,7 but adhesion between the copper film and barrier metal layer was poor and the deposition rate was slow. Copper electroless plating, which does not require a sputtered Cu seed layer, is an efficient means of filling high-aspect-ratio holes and has became increasingly important.…”

“…Copper electroless plating, which does not require a sputtered Cu seed layer, is an efficient means of filling high-aspect-ratio holes and has became increasingly important. 8,9 When the aspect ratio ͑a rate of hole depth to hole diameter͒ is higher than 3, it is difficult for normal electroless plating to fill the high aspect via hole. Recently, we found that a continuous Cu seed layer as thin as 10 nm could be deposited by electroless plating on 1 nm Pd layer formed by the ionized cluster beam ͑ICB͒ and the adhesion between electroless-plated Cu film and TaN barrier layer was good enough to endure chemical mechanical polishing ͑CMP͒.…”

Nucleation Kinetics of Electroless Cu Deposition on Ruthenium Using Glyoxylic Acid as a Reducing Agent

“…[12][13][14] Furthermore, it is attractive for replacing conventional PVD Cu seed layers in dual-damascene fabrication of Cu interconnects. [15][16][17][18] Recently, we reported a feasibility study for TSV metallization seed layer using Ru as catalytic underlayer for ELD Cu. 10,11 The ELD Cu was deposited inside TSVs along the sidewalls.…”