Cobalt Interconnection Plating via Dual-Rate Electroplating
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Solution Overview
Problem
Current microelectronic device fabrication processes face challenges with copper plating, particularly in maintaining void-free copper filling of small features and the need for a barrier layer to prevent copper diffusion, which is inefficient and difficult to scale down.
Innovation Solution
A dual-chamber electroplating system using cobalt ions in two different deposition rates, with a slow cobalt plating chamber for filling small features and a fast cobalt plating chamber for high-volume manufacturing, along with a processing system that includes multiple chambers for cleaning, annealing, and contact ring configurations to manage resistance and prevent joule heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If copper is used for plating, then high conductivity is achieved, but a barrier layer is required to prevent copper diffusion into the substrate
Solution Approach 1:
The patent changes the material parameter from copper to cobalt, which fundamentally alters the diffusion behavior. Cobalt does not diffuse into silicon or dielectric materials, eliminating the need for a barrier layer while maintaining acceptable electrical conductivity for interconnection applications.
Solution Approach 2:
The patent extracts and removes the barrier layer component from the interconnection structure by using cobalt instead of copper. This eliminates the need for additional tantalum nitride or other barrier layers, simplifying the overall device structure.
2Length of moving object
If feature size is reduced, then device scaling is achieved, but the barrier layer occupies a relatively larger volume
Solution Approach 1:
By changing the material parameter from copper to cobalt, the patent eliminates the barrier layer requirement entirely. This resolves the volume occupation issue as cobalt's non-diffusing nature into substrates removes the need for protective barrier structures regardless of feature size scaling.
3Quantity of substance
If copper plating is used for small features, then filling is achieved, but void-free filling becomes increasingly difficult
Solution Approach 1:
The patent changes the plating material from copper to cobalt, which exhibits different electrochemical deposition characteristics. Cobalt plating provides better void-free filling performance in small features due to its deposition behavior and ability to conformally coat complex geometries without forming voids.
4Device complexity
If cobalt is used instead of copper, then barrier layer is not required, but resistance is higher
Solution Approach 1:
While cobalt has higher resistivity than copper (6 uOhm-cm vs 2 uOhm-cm), the patent accepts this trade-off to eliminate the barrier layer requirement. The overall system performance is improved by removing the barrier layer, and the higher cobalt resistance is managed through appropriate interconnection design and dimensions.
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
Enables efficient and consistent cobalt plating without a barrier layer, improving feature filling and reducing resistance issues, while maintaining high throughput and quality in microelectronic device production.
Implementation Method 1
A wafer electroplating system has at least one first electroplating chamber having a first electrolyte containing cobalt ions, and is adapted to electroplate a cobalt film onto a wafer
Data Source
AI summary
A wafer electroplating system has at least one first electroplating chamber having a first electrolyte containing cobalt ions, and is adapted to electroplate a cobalt film onto a wafer at a first deposition rate. A second electroplating chamber has a second electrolyte containing cobalt ions, and is adapted to electroplate a cobalt film onto the wafer at a second deposition rate faster than the first deposition rate. The first and second electroplating chambers are within an enclosure of a processing system. A robot moves a wafer among the first and second electroplating chambers.