Copper Coating Conformality via ALD Catalyst and Reducing Agent
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Solution Overview
Problem
Current methods for depositing thin copper layers, such as cathode sputtering and chemical vapor deposition, face challenges like non-uniformity, void formation, and agglomeration, especially in high aspect ratio structures, which affect the conformality and adhesion of copper layers on semiconductor substrates.
Innovation Solution
The use of atomic layer deposition (ALD) with a copper complex as the first precursor and a ruthenium, nickel, or palladium complex as the second precursor, allowing for a reduction step at low temperatures to convert copper oxide films to metallic copper, thereby improving conformality and avoiding agglomeration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If physical methods like cathode sputtering are used to deposit thin copper layers, then the deposition process can be performed, but uniform closed surface layers are not obtained and voids are created in high aspect ratio structures
Solution Approach 1:
The patent introduces an intermediary reducing agent (hydrogen plasma or organic reducing agents like formic acid, isopropanol, or glucose) that mediates the reduction of copper oxide to metallic copper. This intermediary enables the transformation at low temperatures without direct high-temperature processing, achieving conformal copper layers in high aspect ratio structures that physical methods cannot deposit uniformly
Solution Approach 2:
The patent changes the temperature parameter from high temperatures (>300°C) required by conventional methods to low temperatures (room temperature to 200°C) by using the intermediary reducing agent. This parameter change enables the deposition of uniform copper layers in high aspect ratio structures while maintaining adhesion and avoiding void formation
2Manufacturing precision
If chemical vapor deposition is used to produce copper layers, then layer formation can occur, but the layer growth is not uniform and closed surface layers form only from a thickness of a few 10 nm
Solution Approach 1:
The patent employs periodic pulsed deposition cycles where copper oxide is deposited and then reduced in alternating steps. This periodic action allows uniform layer growth from the first nanometer, creating closed surface layers at much thinner dimensions than conventional CVD, while maintaining manufacturing simplicity
Solution Approach 2:
The patent replaces the thermal field (high temperature) with a chemical field (reducing agent) to achieve copper reduction. This substitution enables uniform layer growth at low temperatures, allowing closed surface layers to form at minimal thickness without the limitations of conventional high-temperature CVD
3Manufacturing precision
If high process temperatures are used to reduce copper in precursor molecules, then copper layers can be formed, but agglomeration occurs which degrades layer quality
Solution Approach 1:
The patent uses a reducing agent as an intermediary substance that enables copper reduction at low temperatures. This intermediary (hydrogen plasma, formic acid, isopropanol, or glucose) facilitates the chemical reduction of copper oxide to metallic copper without requiring high temperatures, thereby preventing agglomeration and maintaining layer quality
Solution Approach 2:
The patent fundamentally changes the temperature parameter from >300°C to room temperature or mildly elevated temperatures (up to 200°C) by introducing the reducing agent intermediary. This parameter change eliminates agglomeration while achieving complete copper layer formation with high manufacturing precision
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
This approach enables the production of highly conformal, uniform copper layers with improved adhesion and reduced agglomeration, even in complex geometries, by using the second precursor as a catalyst for thermal reduction at low temperatures.
Implementation Method 1
The first reactant is initially chemisorbed on the substrate surface so that the substrate is substantially covered with a monolayer of the precursor
Implementation Method 2
allowing for a reduction step at low temperatures to convert copper oxide films to metallic copper
Implementation Method 3
by using the second precursor as a catalyst for thermal reduction at low temperatures
Data Source
AI summary
A method for producing a substrate with a copper or a copper-containing coating is disclosed. The method comprises a first step wherein a first precursor, a second precursor and a substrate are provided. The first precursor is a copper complex that contains no fluorine and the second precursor is selected from a ruthenium complex, a nickel complex, a palladium complex or mixtures thereof. In the second step, a layer is deposited at least on partial regions of a surface of the substrate by using the first precursor and the second precursor by means of atomic layer deposition (ALD). The molar ratio of the first precursor:second precursor used for the ALD extends from 90:10 to 99.99:0.01. The obtained layer contains copper and at least one of ruthenium, nickel and palladium. Finally, a reduction is performed step in which a reducing agent acts on the substrate obtained after depositing the copper-containing layer.