Direct seed electroplating of copper on ruthenium liners

Additives for Bottom-up Copper Plating from an Alkaline Complexed Electrolyte

“…In this context, alkaline complexed-Cu electrolytes have been developed to achieve high Cu nucleation density and uniform plating. [5][6][7][8] In addition to their application in direct Cu plating, these electrolytes are advantageous even in conventional interconnect metallization due to the lower susceptibility for seed layer dissolution in an alkaline medium. 9 Proposed integration schemes for direct Cu plating rely on two process steps: (i) a Cu nucleation step, utilizing an alkaline complexed-Cu electrolyte; and (ii) a bottom-up fill step, utilizing a conventional acid-Cu electrolyte with additives.…”

Direct Copper Electrochemical Deposition on Ru-Based Substrates for Advanced Interconnects Target 30 nm and ½ Pitch Lines: From Coupon to Full-Wafer Experiments

“…One option for metallization of sub-30 nm narrow lines, being thoroughly studied in recent years, is to eliminate the PVD Cu seed layer deposition step, along with a reduction in Ta/TaN barrier film thickness down to 1.5 nm on top of which a few nanometer Plasma-Enhanced Atomic Layer Deposited (PEALD) film of Ru or Ru alloy is deposited. [2][3][4][5][6][7] While materials such as Ta/TaN act as extremely robust diffusion barriers even at thicknesses as low as 1.5 nm, they do not support direct electrodeposition of copper. [8][9][10] The advantage of our approach is that plated Cu is known to possess an excellent adhesion and wettability to Ru.…”