Cobalt Electrodeposition via Acidic Alpha-Hydroxy Carboxylic Additives
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Solution Overview
Problem
Conventional electrodeposition processes for cobalt in semiconductor devices face challenges such as slow filling speeds, high impurity content, and material voids, making them costly and inefficient for industrial-scale production.
Innovation Solution
An electrolyte solution with cobalt II ions, chloride ions, and alpha-hydroxy carboxylic acids at a pH between 2.0 and 4.0 is used for conformal electrodeposition, eliminating the need for multiple deposition steps and organic additives, thereby reducing impurities and voids while increasing deposition speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electrodeposition processes use multiple organic additives (suppressor and accelerator) to achieve bottom-up filling, then material voids are prevented and filling quality is improved, but impurity content increases and deposition speed decreases
Solution Approach 1:
The invention extracts and eliminates the harmful organic additives (suppressor and accelerator) from the electrodeposition bath while maintaining the bottom-up filling mechanism. By removing these additives that cause impurity contamination, the process achieves high-purity cobalt deposits without material voids, resolving the contradiction between filling quality and impurity content
Solution Approach 2:
The invention changes the pH parameter to a highly acidic range (pH 1-3), which fundamentally alters the electrodeposition mechanism. This parameter change enables the use of simple electrolyte compositions without complex organic additives, achieving both high purity and void-free filling simultaneously
2Manufacturing precision
If conventional electrodeposition processes use multiple organic additives to achieve bottom-up filling, then material voids are prevented, but deposition speed becomes too slow for industrial production
Solution Approach 1:
By changing the pH to a highly acidic range (pH 1-3) and using a simplified electrolyte composition without complex organic additives, the invention achieves both high deposition speeds compatible with industrial production and high-quality void-free filling. The acidic environment enables faster electrodeposition kinetics while maintaining filling quality
3Manufacturing precision
If conventional electrodeposition processes use suppressor and accelerator additives, then bottom-up filling is achieved, but the process complexity and cost increase
Solution Approach 1:
The invention extracts and removes the complex system of organic additives (suppressor and accelerator) from the electrodeposition process. By eliminating these complex components, the process becomes simpler and more cost-effective while still achieving the desired bottom-up filling mechanism through pH-controlled electrodeposition
Solution Approach 2:
The invention replaces the complex additive-based control mechanism with a simpler pH-based control mechanism. By operating at highly acidic pH (1-3), the process achieves bottom-up filling through fundamental electrochemical principles rather than complex organic molecule interactions, reducing process complexity
4Manufacturing precision
If conventional electrodeposition processes use alkaline or neutral pH electrolytes with multiple additives, then filling quality is maintained, but cobalt hydroxide forms and conductivity decreases
Solution Approach 1:
The invention changes the pH parameter to a highly acidic range (pH 1-3), which prevents the formation of cobalt hydroxide precipitates that would compromise conductivity. This parameter change ensures that cobalt deposits maintain high electrical conductivity while still achieving high-quality void-free filling through the acidic electrodeposition mechanism
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 high-purity, void-free cobalt interconnections with reduced impurity content and faster deposition rates, compatible with industrial production, and prevents the formation of cobalt hydroxide, enhancing the conductivity and performance of semiconductor devices.
Implementation Method 1
The present invention relates to the electrodeposition of cobalt on a conductive surface
Implementation Method 2
An electrolyte solution with cobalt II ions, chloride ions, and alpha-hydroxy carboxylic acids
Data Source
AI summary
The present invention relates to a process for the fabrication of cobalt interconnections and to an electrolyte which enables the implementation thereof. The electrolyte which has a pH below 4.0 comprises cobalt ions, chloride ions and at most two organic additives of low molecular weight. One of these additives may be an alpha-hydroxy carboxylic acid or a compound having a pKa value ranging from 1.8 to 3.5.