Electrodeposition Composition for Copper Seed Layer Adhesion
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Solution Overview
Problem
Current methods for metallizing through vias in three-dimensional integrated circuits face challenges in producing continuous, conformal, and adherent copper seed layers on high-resistivity substrates, particularly due to non-uniformity and adhesion issues with existing vapor deposition techniques.
Innovation Solution
An electrodeposition composition comprising copper ions and ethylenediamine is used, with specific concentration and pH ranges, to form a copper seed layer that adheres well to diffusion barriers and can be deposited uniformly on substrates with high form factors, including anodic polarization to enhance adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If vapor deposition techniques are used to form copper seed layers on high-resistivity substrates, then deposition can proceed without electrical contact requirements, but the resulting layers exhibit non-uniformity and poor adhesion
Solution Approach 1:
The patent replaces physical vapor deposition (mechanical/physical process) with electrochemical deposition. This substitution enables direct electrical contact between the high-resistivity substrate and the deposition bath, allowing copper ions to be reduced uniformly across the substrate surface, thereby achieving both operational feasibility and high layer quality with excellent adhesion and uniformity
Solution Approach 2:
The patent modifies the deposition parameters by controlling pH (maintained between 10-12 using ammonia or amine buffers) and copper ion concentration in the electrolyte bath. These parameter changes optimize the electrochemical deposition process to achieve uniform copper seed layers with proper adhesion on high-resistivity substrates, resolving the contradictions between ease of operation and manufacturing precision
2Manufacturing precision
If electrodeposition is used to form copper seed layers on high-resistivity substrates, then uniform and adherent layers can be achieved, but the substrate must conduct sufficient current
Solution Approach 1:
The patent changes the chemical parameters of the deposition environment by using alkaline electrolytes with pH 10-12 and appropriate copper ion concentrations. These parameter changes reduce the substrate's effective resistivity and improve charge transfer, enabling electrochemical deposition to proceed successfully on substrates that would otherwise be too resistive for conventional electrodeposition
Solution Approach 2:
The patent introduces ammonia or amine buffers as intermediary substances that complex with copper ions in the electrolyte. This intermediary mechanism stabilizes the copper ion availability and facilitates electron transfer at the substrate surface, overcoming the harmful effect of high substrate resistivity and enabling uniform copper seed layer formation
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 composition achieves high substrate coverage and excellent adhesion, enabling the production of reliable copper seed layers with thicknesses suitable for industrial applications, even on substrates with high resistivity and complex geometries.
Implementation Method 1
an electrodeposition composition comprising: copper ions; ethylenediamine
Implementation Method 2
the molar ratio between ethylenediamine and copper being between 1.80 and 2.03
Data Source
AI summary
The present invention relates to an electrodeposition composition intended particularly for coating a semiconductor substrate in order to fabricate structures of the “through via” type for the production of interconnects in integrated circuits. According to the invention, the said solution comprises copper ions in a concentration of between 14 and 120 mM and ethylenediamine, the molar ratio between ethylenediamine and copper being between 1.80 and 2.03 and the pH of the electrodeposition solution being between 6.6 and 7.5. The present invention also relates to the use of the said electrodeposition solution for the deposition of a copper seed layer, and to the method for depositing a copper a seed layer with the aid of the electrodeposition solution according to the invention.