Electroless Copper Deposition Seed Layer
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Solution Overview
Problem
Traditional deposition processes face challenges in reliably filling nanometer-sized features with high aspect ratios, particularly with copper-containing materials, due to issues with nucleation and adhesion on non-metallic or oxidized surfaces, leading to defects like voids and seams.
Innovation Solution
A method involving the selective deposition of a seed layer using collimated physical vapor deposition (PVD) on a barrier layer, followed by an electroless deposition process with a copper-containing solution, including additives like accelerators and levelers, to ensure uniform coverage and adhesion, maintaining the sidewalls free of seed material and controlling the angle of copper deposition to minimize defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional deposition processes are used to fill nanometer-sized features with high aspect ratios, then the features can be filled with copper-containing material, but defects such as voids and seams occur due to poor nucleation and adhesion on non-metallic or oxidized surfaces
Solution Approach 1:
A seed layer is deposited beforehand on the bottom surface of the feature and on the sidewalls before the electroless copper deposition process. This preliminary seed layer provides a catalytic surface that enables reliable nucleation and growth of the copper-containing material, preventing voids and seams that would otherwise form on non-metallic or oxidized surfaces.
Solution Approach 2:
The seed layer acts as an intermediary between the non-metallic barrier layer/oxidized surface and the copper-containing material. It provides the necessary catalytic properties for electroless deposition to occur reliably, bridging the gap between surfaces that would otherwise be incompatible for direct copper growth.
2Manufacturing precision
If a seed layer is deposited to provide catalytic surface for electroless deposition, then uniform copper coverage is achieved, but the sidewalls may be contaminated with seed material during deposition
Solution Approach 1:
The seed layer is selectively deposited on specific surfaces (bottom surface and sidewalls) with different properties or thicknesses tailored to local requirements. The bottom surface receives a seed layer optimized for adhesion to the barrier layer, while the sidewalls receive a seed layer configured to provide catalytic activity without excessive material that could contaminate adjacent features.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively fills features with a copper-containing layer free of defects, ensuring reliable and uniform deposition, even in high aspect ratio structures, enhancing the quality of nanometer-sized interconnects in semiconductor devices.
Implementation Method 1
selectively depositing a seed layer onto a bottom surface of a feature on a substrate during a collimated physical vapor deposition (PVD) process
Implementation Method 2
depositing a copper-containing layer on the seed layer to fill the feature during an electroless deposition process. An electroless deposition process, unlike electroplating processes, utilizes autocatalyzed chemical deposition instead of an applied current to induce chemical reduction.
Data Source
AI summary
Embodiments of the invention provide methods for forming conductive materials within contact features on a substrate by depositing a seed layer within a feature and subsequently filling the feature with a copper-containing material during an electroless deposition process. In one example, a copper electroless deposition solution contains levelers to form convexed or concaved copper surfaces. In another example, a seed layer is selectively deposited on the bottom surface of the aperture while leaving the sidewalls substantially free of the seed material during a collimated PVD process. In another example, the seed layer is conformably deposited by a PVD process and subsequently, a portion of the seed layer and the underlayer are plasma etched to expose an underlying contact surface. In another example, a ruthenium seed layer is formed on an exposed contact surface by an ALD process utilizing the chemical precursor ruthenium tetroxide.