Copper Electrodeposition Bath Using Inert Cations for Trench Filling
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Solution Overview
Problem
Existing methods for electrodeposition of copper seed layers on barrier materials in integrated circuits face challenges in achieving conformal, defect-free deposition in small trenches, leading to voids and increased resistance, especially as device miniaturization requires thinner seed layers and higher form factor trenches.
Innovation Solution
An electrolyte solution containing copper ions, aromatic amines, and electrochemically inert cations such as cesium or alkylammonium is used for electrodeposition, which improves nucleation and suppresses copper deposition defects, allowing for continuous, conformal copper filling of fine trenches without the need for a pre-deposited seed layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If physical vapor deposition is used to deposit copper seed layer, then the deposition process is simple and fast, but the deposited copper does not have constant thickness and shows discontinuity on sidewalls creating voids
Solution Approach 1:
The patent replaces physical vapor deposition (PVD) with electrochemical deposition to deposit copper seed layers. This substitution enables conformal, uniform deposition on trench sidewalls and bottom, eliminating the thickness variation and void formation characteristic of PVD methods.
Solution Approach 2:
The patent introduces a specifically formulated electrolyte containing aromatic amines and electrochemically inert cations as an intermediary medium. This electrolyte enables direct electrochemical deposition of copper on barrier materials, serving as a mediator that facilitates uniform seed layer formation without requiring PVD processes.
2Ease of manufacture
If existing electrolytes are used for copper electrodeposition, then the filling process is straightforward, but voids form in copper deposit of high form factor trenches increasing resistance or causing breaks
Solution Approach 1:
The patent modifies electrolyte composition parameters by adding aromatic amines and electrochemically inert cations. These parameter changes in the electrolyte formulation enable complete, void-free filling of high form factor trenches while maintaining process simplicity.
Solution Approach 2:
The patent creates a composite electrolyte system combining traditional copper salts with aromatic amine additives and electrochemically inert cations. This composite electrolyte composition synergistically achieves both ease of manufacture and high reliability by preventing void formation during trench filling.
3Volume of moving object
If trench size is reduced for miniaturization, then the storage density increases, but the seed layer thickness must decrease making continuous conformal deposition difficult
Solution Approach 1:
The patent changes electrolyte composition parameters by incorporating aromatic amines and electrochemically inert cations, which enable precise control of copper deposition at ultra-thin scales. This allows continuous conformal deposition even when seed layer thickness must be reduced to 5 nm or less for 20 nm trenches.
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 enables defect-free filling of trenches with high form factors and small opening dimensions, reducing voids and ensuring continuous copper deposits with high conformity, suitable for advanced integrated circuit interconnects.
Implementation Method 1
an electrolyte for electrodeposition of copper on a substrate
Implementation Method 2
electrochemical deposition
Implementation Method 3
a promoter of nucleation of metallic copper on said substrate
Data Source
AI summary
The present invention relates to an electrolyte composition for depositing copper on metal substrates. The composition contains a combination of two aromatic amines and an electrochemically inert cation. This electrolyte makes it possible to increase the copper nucleation density. It also allows bottom-up filling in trenches that have a very small opening dimension, typically lower than 40 nm.