Copper Interconnect Electroplating for (111) Nanotwinned Grain Control
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Solution Overview
Problem
As semiconductor devices continue to integrate more components into a given area with reduced minimum feature sizes, challenges arise in forming conductive features with uniform grain orientation and low surface roughness during the electroplating process, which can lead to voids and cracks.
Innovation Solution
The use of additives in a copper electroplating process, including a weak suppressor, strong suppressor, and leveler, promotes the growth of nanotwinned copper with a (111)-oriented crystalline structure, ensuring uniform grain orientation and low surface roughness by controlling the deposition process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electroplating process is used to deposit copper, then copper deposition is achieved, but non-uniform grain orientation and high surface roughness occur leading to voids and cracks
Solution Approach 1:
The patent applies parameter changes by modifying the electroplating solution composition to include specific additives (suppressors and levelers) that control copper grain growth. These chemical parameter changes result in uniform (111)-oriented grain structure and smooth surface morphology, preventing voids and cracks while maintaining high copper density and electrical conductivity.
2Productivity
If feature size is reduced to increase integration density, then more components can be integrated, but manufacturing precision and control of grain orientation become more difficult
Solution Approach 1:
The patent uses parameter changes in the electroplating process, specifically incorporating suppressor additives that adsorb to copper crystal surfaces and direct grain growth toward the (111) orientation. This chemical control mechanism remains effective at reduced feature sizes, enabling precise grain orientation control even as integration density increases and minimum feature dimensions decrease.
3Ease of manufacture
If electroplating is performed without specialized additives, then process simplicity is maintained, but surface roughness increases and voids form
Solution Approach 1:
The patent introduces intermediary substances (additives such as suppressors and levelers) into the electroplating solution. These intermediaries mediate the copper deposition process by adsorbing to specific crystal planes and growth sites, controlling grain orientation and surface morphology. The additives act as mediators between the electroplating process and the copper deposit, achieving smooth surfaces and uniform grain structure without significantly complicating the overall manufacturing 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 enables the formation of conductive features with at least 97% (111)-oriented copper, reducing the risk of voids and cracks, and achieving smooth, planar surfaces with improved mechanical and conductive properties.
Implementation Method 1
The use of additives in a copper electroplating process, including a weak suppressor, strong suppressor, and leveler, promotes the growth of nanotwinned copper with a (111)-oriented crystalline structure
Implementation Method 2
promotes the growth of nanotwinned copper with a (111)-oriented crystalline structure, ensuring uniform grain orientation and low surface roughness
Data Source
AI summary
A method includes adding a first additive to an electroplating solution, wherein the first additive is a relatively weak suppressing agent; adding a second additive to the electroplating solution, wherein the second additive is a relatively strong suppressing agent; adding a third additive to the electroplating solution, wherein the third additive is a leveling agent; and depositing copper using the electroplating solution, wherein most of the copper is nanotwinned grains having a (111)-orientation.