Void-Free Ruthenium Electroplating via Rate-Controlled Deposition
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Solution Overview
Problem
Conventional electroplating methods for ruthenium-containing materials in semiconductor processing often result in voids and non-uniform thicknesses due to variations in deposition rates across non-planar features, leading to performance-degrading defects in electroplated ruthenium lines, especially in high-aspect-ratio openings.
Innovation Solution
The method involves electrochemical deposition of ruthenium-containing materials with a seed layer on patterned substrates, where the deposition rate is controlled by varying the concentration of bismuth ions and applying a voltage to ensure a bottom-up deposition process, preventing premature pinching off and void formation by maintaining a higher deposition rate on the bottom surface compared to the sidewalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electroplating is performed on non-planar features, then metal ions deposit to form conductive layers, but the deposition rate varies across different points causing voids and non-uniform thickness
Solution Approach 1:
The patent applies local quality by using a dual-bath electroplating system where different electrolyte compositions are used for different regions: a first bath for depositing ruthenium on the bottom surface and a second bath for depositing copper on the sidewalls. This regional differentiation allows each surface to receive optimized deposition conditions, ensuring uniform thickness and eliminating voids by addressing the non-planar feature's varying geometric requirements locally rather than uniformly across the entire structure
Solution Approach 2:
The patent segments the deposition process into distinct stages and regions: first depositing ruthenium on the bottom surface using a ruthenium-containing electrolyte, then depositing copper on the sidewalls using a copper-containing electrolyte. This segmentation of the deposition process into separate operational phases with different material compositions allows precise control over thickness uniformity and eliminates the void formation problem that occurs when a single uniform deposition approach is used on non-planar features
2Productivity
If electroplating is performed to fill high-aspect-ratio openings, then conductive material is deposited, but premature pinching off occurs leading to void formation
Solution Approach 1:
The patent applies preliminary action by first depositing a ruthenium layer on the bottom surface of the opening before depositing copper on the sidewalls. This preliminary ruthenium deposition creates a conductive base layer that prevents premature pinching off during subsequent copper deposition, ensuring that the opening remains open for adequate copper fill and eliminating void formation in high-aspect-ratio structures
Solution Approach 2:
The patent changes deposition parameters by using different electrolyte compositions and deposition conditions for different materials and locations: ruthenium deposition parameters optimized for bottom surface coverage, followed by copper deposition parameters optimized for sidewall filling. This parameter differentiation ensures controlled deposition rates that prevent premature pinching off while maintaining void-free filling in high-aspect-ratio openings
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 results in void-free ruthenium-containing lines with improved electrical conductivity and higher throughput compared to traditional deposition techniques, reducing electromigration and electrical resistance issues in high-density interconnects.
Implementation Method 1
applying a current to the patterned substrate that includes the seed layer to plate a first portion of the ruthenium-containing material on the bottom surface of the opening at a first deposition rate and a second portion of ruthenium-containing material on the sidewalls of the opening at a second deposition rate
Implementation Method 2
contacting the patterned substrate that includes the seed layer with an electrochemical plating fluid that includes greater than or about 0.1 M ruthenium ions and greater than or about 1×10−5 M bismuth ions
Data Source
AI summary
Exemplary methods of electroplating may include providing a patterned substrate having at least one opening, where the opening includes one or more sidewalls and a bottom surface. The methods may also include plating a first portion of ruthenium-containing material on the bottom surface of the opening at a first deposition rate and a second portion of ruthenium-containing material on the sidewalls of the opening at a second deposition rate, where the first deposition rate is greater than the second deposition rate. The methods may be used to make integrated circuit devices that include void-free, electrically-conductive lines and columns of ruthenium-containing materials.