Magi Margalit Nagar

Copper Plating on Resistive Substrates, Diffusion Barrier and Alternative Seed Layers

We have studied electrochemical deposition of copper on ruthenium-tantalum (Ru-Ta) alloy, tantalum (Ta), and cobalt (Co) substrates using cyclic voltammetry and galvanostatic methods. We show that a single-step direct-plating from acidic Cu bath approach is favorable on thin Ru-Ta films, while it presents a significant challenge for plating on resistive Ta and Co substrates.

Direct Copper Electrochemical Deposition on Ru-Based Substrates for Advanced Interconnects Target 30 nm and 1/2 Pitch Lines: From Coupon to Full-Wafer Experiments

Extending copper electrochemical deposition to 3x nm nodes and beyond requires a new plating approach that is not constrained by typical PVD copper seed step coverage performance. To this purpose, we propose a copper direct plating process on Plasma Enhanced Atomic Layer Deposition (PEALD) Ru-based resistive substrates, where the Cu seed is deposited in-situ during the front propagation from the edge to the center of the wafer. In order to understand the full-wafer copper direct plating process that occurs on these liners, the effect of plating tool advanced features, applied waveform, plating chemistry and substrate surface activation on the subsequent plated copper nucleation behavior are studied.

Nucleation and Growth of Copper on Ru-Based Substrates: II. The Effect of the Suppressor Additive

The effect of the molecular mass (Mm) of polyethylene glycol (PEG) and its derivatives on the copper island density (Np) on ruthenium-tantalum (RuTa) alloy was investigated by utilizing scanning electron microscopy (SEM) and galvanostatic methods. The experimental results show that the island density is affected by the strength of suppression which can be modified by using different suppressor molecules. Furthermore, we use galvanostatic measurements to evaluate the suppression strength and show that potential-time transients recorded during galvanostatic deposition of Cu can be used to estimate the island density.

Nucleation and Growth of Copper on Ru-Based Substrates: I. The Effect of the Inorganic Components

The effect of the inorganic components, namely copper sulfate (CuSO4), sulfuric acid (H2SO4) and hydrochloric acid (HCl) on the nucleation and growth of copper on Ru-based substrate is reported in the absence and the presence of a suppressor molecule, polyethylene glycol (PEG). In the absence of PEG it was found that the island density, Np was the highest when CuSO4 and HCl concentrations were low while H2SO4 concentration was high. The effect of each component remained similar when all components were mixed together. In the presence of PEG, the effect of CuSO4 and H2SO4 remained similar. However, for the HCl, an optimal concentration was found where Np reached a maximum value. The study illustrates the importance of an optimal bath composition toward faster coalescence of the Cu islands into a continuous Cu film for direct plating applications.

Tailoring Copper Island Density for Copper Plating on a RuTa Substrate

The electrochemical nucleation and growth of copper on a ruthenium-tantalum (RuTa) alloy has been studied using galvanostatic methods. The experimental results show that the island density is highly dependent on the bath composition and deposition parameters. High island density was achieved with higher applied current, addition of suppressor and low copper concentration in the plating bath.