Semiconductor Metal Structure Adhesion via Auxiliary Layer Stack
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Solution Overview
Problem
Existing metal structures in semiconductor devices face issues with delamination due to cyclic thermal stress, leading to potential overheating and irreversible damage, as conventional metal diffusion barrier layers provide inadequate adhesion and are prone to delamination.
Innovation Solution
Incorporating an auxiliary layer stack between the metal structure and the conductive structure, which includes an adhesion layer containing a second metal with higher binding energy and a metal diffusion barrier layer, to enhance adhesion and reduce thermo-mechanical stress, with the adhesion layer forming a solid solution or intermetallic phase with the metal structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional metal diffusion barrier layer is used between the metal structure and conductive structure, then metal atom diffusion is prevented, but adhesion is inadequate leading to delamination under cyclic thermal stress
Solution Approach 1:
The auxiliary layer stack segments the interface between metal structure and conductive structure into multiple functional layers: adhesion layer (with second metal), metal diffusion barrier layer, and auxiliary barrier layer. This segmentation allows each layer to specialize in one function - the adhesion layer provides strong bonding, the barrier layer prevents metal diffusion, and the auxiliary barrier layer provides additional protection, collectively resolving the adhesion-strength contradiction.
Solution Approach 2:
The auxiliary layer stack employs composite material structure combining different metals and barrier materials. The adhesion layer contains a second metal with higher binding energy that forms strong bonds with both the metal structure (first metal) and the conductive structure, creating a composite interface that simultaneously achieves strong adhesion and prevents metal diffusion.
2Temperature
If the metal diffusion barrier layer is made thinner to maintain thermal conductivity, then thermal performance is improved, but adhesion and diffusion barrier effectiveness are reduced
Solution Approach 1:
The barrier function is segmented between the metal diffusion barrier layer and auxiliary barrier layer. This allows the metal diffusion barrier layer to be optimized for diffusion prevention while the auxiliary barrier layer provides additional protection, enabling thinner overall barrier structure that maintains thermal conductivity while ensuring adequate adhesion and diffusion barrier effectiveness.
Solution Approach 2:
The adhesion layer acts as an intermediary between the metal structure and barrier layers. It contains a second metal with higher binding energy that forms strong bonds with both the first metal (metal structure) and the conductive structure, mediating the mechanical and thermal stress transfer and preventing delamination even when barrier layers are thin.
3Reliability
If an auxiliary layer stack with adhesion layer containing second metal is added, then adhesion and stress resistance are enhanced, but device complexity increases
Solution Approach 1:
The auxiliary layer stack components serve multiple functions: the adhesion layer provides both adhesion and stress buffering; the metal diffusion barrier layer prevents metal diffusion while maintaining thermal conductivity; the auxiliary barrier layer provides additional diffusion protection and structural support. This multi-functionality reduces the need for separate dedicated layers for each function, managing complexity while achieving reliable bonding.
Solution Approach 2:
The invention changes material parameters by selecting a second metal with higher binding energy than the first metal for the adhesion layer. This parameter change (binding energy) enables the adhesion layer to form strong bonds with both the metal structure and conductive structure, enhancing bonding stability without requiring complex structural modifications.
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 solution effectively improves the bonding between the metal structure and the metal diffusion barrier layer, reducing the risk of delamination and maintaining the thermal conductivity of the metal structure, thereby enhancing the reliability and stability of the semiconductor device.
Implementation Method 1
the adhesion layer forming a solid solution or intermetallic phase with the metal structure
Implementation Method 2
the adhesion layer forming a solid solution or intermetallic phase with the metal structure
Implementation Method 3
A metal diffusion barrier layer prevents metal atoms from diffusing from the metal structure into structures in the semiconductor die
Implementation Method 4
an auxiliary layer stack is sandwiched between the conductive structure and the metal structure... to enhance adhesion and reduce thermo-mechanical stress
Data Source
AI summary
A method of manufacturing a semiconductor device includes forming a semiconductor substrate that has a conductive structure, and forming a precursor auxiliary layer stack on a first section of the conductive structure. The precursor auxiliary layer stack has a precursor adhesion layer and a precursor barrier layer between the precursor adhesion layer and the conductive structure. The precursor adhesion layer contains a second metal. The method further includes forming, on the precursor auxiliary layer stack, a metal structure containing a first metal and forming, from portions of the precursor auxiliary layer stack an adhesive layer containing the first and second metals.