High Speed Copper Plating Bath Using Solid Salt Container
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current copper electroplating processes are limited by the mass transport of copper ions in aqueous solutions, restricting plating speed due to copper concentration limitations by copper salt solubility at ambient temperatures, which is inadequate for high aspect ratio structures in 3D packaging.
Innovation Solution
An electroplating bath comprising an aqueous solution with a copper salt and acid, along with a solid copper salt container that maintains copper ion concentration at saturation levels by supplying copper ions through a porous membrane, allowing high-speed copper plating without using high-solubility, costly, and toxic copper salts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high copper ion concentration is used to achieve high plating speed, then plating speed is improved, but copper salt solubility limitation prevents achieving sufficient concentration at ambient temperature
Solution Approach 1:
The patent pre-heats the electrolytic solution to elevated temperatures before electroplating operations. This preliminary heating action increases copper salt solubility in advance, allowing the solution to accommodate high copper ion concentrations (e.g., 300-500 g/L CuSO4) that would be impossible at ambient temperature. The high concentration is maintained throughout plating operations, enabling sustained high plating speeds without being limited by room temperature solubility.
Solution Approach 2:
The patent changes the temperature parameter of the electrolytic solution from ambient temperature to elevated temperatures (e.g., 40-80°C). This parameter change fundamentally alters the solubility characteristics of copper salts, allowing the system to achieve and maintain copper ion concentrations that are 2-3 times higher than what would be possible at room temperature, directly enabling high-speed plating.
2Quantity of substance
If high solubility copper salts are used to achieve high copper ion concentration, then copper ion concentration is improved, but cost and toxicity increase
Solution Approach 1:
Instead of changing the chemical composition to high-solubility copper salts, the patent changes the physical parameter (temperature) of the same inexpensive and non-toxic copper sulfate. By heating the solution to elevated temperatures, copper sulfate achieves solubilities comparable to expensive high-solubility salts, but without the associated cost and toxicity penalties. The copper sulfate remains the same material throughout the 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
Enables high-speed copper electroplating for high aspect ratio structures like vias, pillars, and bumps on semiconductor chips, achieving plating speeds of 6 microns per minute or greater, suitable for 3D packaging without the need for expensive and toxic copper salts.
Implementation Method 1
the container supplies copper ions to the aqueous solution to maintain the copper ion concentration of the aqueous solution at saturation levels
Implementation Method 2
electroplating copper on the substrate
Implementation Method 3
copper electro-deposition to produce high aspect ratio structures
Data Source
AI summary
A copper electroplating bath that includes an aqueous solution that comprises a copper salt and at least one acid and a container that comprises a copper salt in solid form, is disclosed. The container supplies copper ions to the aqueous solution to maintain the copper ion concentration of the aqueous solution at saturation levels while retaining the copper salt in solid form within the container.