Alloy Barrier Thin Film for Uniform Copper Seed Layer
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Solution Overview
Problem
Existing electroless copper plating methods face challenges in achieving uniformity and adherence on elemental metals like tungsten and molybdenum, requiring a catalyst layer and a barrier layer, which complicates the formation of ultrafine copper wiring and limits film thickness.
Innovation Solution
A single alloy barrier thin film comprising metal B (such as tungsten or molybdenum) and metal A (like nickel or cobalt) is formed on a substrate, enabling displacement plating with copper ions at a pH of 10 or higher, eliminating the need for a catalyst layer and ensuring improved uniformity and adherence of the copper seed layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electroless copper plating is performed on elemental metals such as tungsten or molybdenum, then the barrier function is provided, but the uniformity and adherence of the copper seed layer are insufficient
Solution Approach 1:
The patent applies composite materials by creating an alloy barrier thin film combining metal B (tungsten or molybdenum) with metal A (nickel or cobalt). This composite structure provides both the barrier function against copper diffusion and the catalytic activity needed for uniform electroless copper plating, eliminating the need for separate barrier and catalyst layers.
Solution Approach 2:
The patent changes the chemical composition parameters of the barrier layer by incorporating metal A (nickel or cobalt) at specific concentrations (1-20 at%) into the metal B matrix. This parameter modification enhances the surface reactivity and catalytic properties, enabling uniform copper seed layer formation without requiring additional catalyst layers.
2Manufacturing precision
If a catalyst metal layer is formed on the barrier layer before electroless plating, then the uniformity of copper seed layer is improved, but the device complexity increases due to bilayer structure
Solution Approach 1:
The patent merges the barrier layer and catalyst layer into a single alloy barrier thin film. By incorporating metal A (nickel or cobalt) into the metal B matrix, the structure simultaneously provides copper diffusion barrier properties and catalytic activity for uniform electroless plating, eliminating the need for a separate catalyst layer and reducing overall structure complexity.
Solution Approach 2:
The alloy barrier thin film performs multiple functions simultaneously: it acts as a barrier to prevent copper diffusion into the substrate, provides catalytic activity for uniform copper seed layer formation, and enables direct electroless plating without additional processing steps. This multi-functionality reduces the number of required layers and simplifies the overall structure.
3Reliability
If a catalyst-imparting step is performed prior to electroless plating, then the adherence of copper seed layer is improved, but the manufacturing process complexity increases
Solution Approach 1:
The patent uses composite materials by forming an alloy barrier thin film that inherently provides catalytic activity through the inclusion of metal A (nickel or cobalt). This eliminates the need for a separate catalyst-imparting step, as the alloy structure itself facilitates uniform copper deposition and strong adherence without additional processing steps.
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 allows for the formation of a uniform, thin copper seed layer with reduced resistance, enabling the fabrication of ultrafine wiring without the complexity of a bilayer structure and achieving film thicknesses of 10 nm or less with excellent adherence and uniformity.
Implementation Method 1
metal B, which has barrier properties in relation to copper and enables displacement plating with the copper ions contained in an electroless copper plating solution
Implementation Method 2
a copper thin film is formed on the alloy barrier thin film by electroless plating using an electroless copper plating solution at pH 10 or higher
Data Source
AI summary
A plated product made of a substrate having formed thereon an alloy barrier thin film for preventing copper diffusion contains metal B, which has barrier properties in relation to copper and enables displacement plating with the copper ions contained in an electroless copper plating solution, and metal A, which tends to have less ionization than metal B in an electroless copper plating solution at a pH of 10 or higher; the alloy barrier thin film for preventing copper diffusion has a composition wherein metal A constitutes between 15 and 35 at % of the atoms; and a copper thin film is formed on the alloy barrier thin film by electroless plating using an electroless copper plating solution at a pH of 10 or higher.