Electroplating Convection Optimization for Mixed Feature Uniformity
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Solution Overview
Problem
In integrated circuit manufacturing, it is challenging to control the relative deposition rates in features of different sizes during electroplating, leading to poor uniformity and within-die non-uniformity due to varying diffusion boundary distances and convection conditions.
Innovation Solution
The implementation of an ultra-low convection stage during electroplating, where electrolyte flow is laminar and mass transport of metal ions is dominated by diffusion over at least 75% of the feature depth, combined with moderate or high convection stages to manage surface convection and additive distribution, allowing for tailored convection conditions to achieve uniform deposition across features of varying sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If moderate or high convection conditions are used during electroplating, then the deposition rate is improved and features are filled faster, but the uniformity of deposition across features of different sizes deteriorates due to varying diffusion boundary distances
Solution Approach 1:
The patent applies dynamic control of convection conditions by transitioning between moderate/high convection stages and ultra-low convection stages during the electroplating process. This dynamic adjustment allows the system to optimize both deposition rate and uniformity at different time points, resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The patent implements periodic cycling between convection stages (moderate/high convection followed by ultra-low convection) to achieve both fast initial filling and subsequent uniformity correction. This periodic action allows the system to benefit from high deposition rates while periodically correcting uniformity issues through diffusion-dominated ultra-low convection periods.
2Quantity of substance
If high convection conditions are applied, then mass transport of metal ions is enhanced, but the relative difference in diffusion boundary distances among features of different sizes increases, leading to poor within-die uniformity
Solution Approach 1:
The patent dynamically transitions from high convection conditions that enhance mass transport to ultra-low convection conditions that equalize diffusion boundary distances. This dynamic control allows the system to first rapidly transport metal ions to features, then correct uniformity by allowing diffusion to dominate when convection is minimized.
Solution Approach 2:
The patent changes the convection parameter during the electroplating process by switching between moderate/high convection stages and ultra-low convection stages. This parameter change allows the system to optimize mass transport at one stage and uniformity at another stage, resolving the contradiction between quantity of substance and manufacturing precision.
3Manufacturing precision
If ultra-low convection conditions are used throughout the entire electroplating process, then within-die uniformity is improved, but the overall deposition rate and productivity decrease
Solution Approach 1:
The patent segments the electroplating process into distinct stages with different convection conditions: moderate/high convection stages for rapid initial deposition and ultra-low convection stages for uniformity control. This segmentation allows each stage to optimize for its specific purpose, combining the benefits of both high productivity and high uniformity.
Solution Approach 2:
The patent uses periodic cycling between moderate/high convection stages (for productivity) and ultra-low convection stages (for uniformity). This periodic action ensures that the system achieves both fast deposition rates and high within-die uniformity by alternating between the two opposing conditions throughout the plating process.
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 improved within-die uniformity and high-quality electroplating results by reducing the relative difference in diffusion boundary distances among features, enabling more uniform plating rates and achieving desired height gaps between features.
Implementation Method 1
flowing electrolyte within or through the electroplating apparatus to provide moderate or high convection conditions at the surface of the substrate
Implementation Method 2
mass transport of metal ions in the electrolyte within the features is dominated by diffusion rather than convection over at least 75% of a depth of the features
Implementation Method 3
electroplating the material onto the substrate while flowing electrolyte within or through the electroplating apparatus
Data Source
AI summary
Various embodiments herein relate to methods and apparatus for electroplating material onto substrates. Often the substrate is a semiconductor substrate. Various techniques described herein utilize a number of different electroplating stages, where the convection conditions vary between the different electroplating stages. In many cases, at least one ultra-low convection stage is used. The ultra-low convection stage may be paired with an initial stage and a final stage that have higher convection conditions. By controlling the convection conditions as described herein, very uniform plating results can be achieved, even when differently sized and/or shaped features are provided on a single substrate.