Nickel Via-Fill Composition for Reliable Boric-Acid-Free Interconnects
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Solution Overview
Problem
Existing metal electrodeposition technologies for microelectronic devices face challenges such as interconnect reliability issues due to copper's susceptibility to oxidation and cracking under thermal cycles, as well as the need for alternatives to boric acid in nickel electrodeposition chemistries.
Innovation Solution
The development of a nickel electrodeposition composition and process for via fill metallization that uses nickel as the primary metal, excludes boric acid, and incorporates polarizer/suppressor and accelerator/depolarizer additives to manage internal stress and ensure complete filling of vias and trenches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If copper is used as the main interconnect conductor metal, then electrical conductivity is improved, but reliability deteriorates due to oxidation and cracking under thermal cycles
Solution Approach 1:
The patent changes the material parameter from copper to nickel, fundamentally altering the chemical and mechanical properties of the interconnect. Nickel provides both adequate electrical conductivity and superior reliability by resisting oxidation and maintaining structural integrity under thermal cycling, thus resolving the contradiction between conductivity and reliability
Solution Approach 2:
The patent employs a composite metal stack structure consisting of nickel and nickel alloy layers with different compositions and properties. This multi-layer composite approach allows optimization of both electrical conductivity and mechanical reliability, with each layer serving specific functions to address the contradiction
2Ease of manufacture
If nickel electrodeposition chemistry uses boric acid, then deposition process is simplified, but environmental safety deteriorates due to toxic byproducts
Solution Approach 1:
The patent removes boric acid from the nickel electrodeposition chemistry, extracting the harmful substance from the process. The simplified chemistry uses alternative buffering agents that are environmentally benign, maintaining processability while eliminating toxic byproducts and addressing environmental safety concerns
Solution Approach 2:
The patent changes the chemical composition parameters of the electrodeposition electrolyte by substituting boric acid with alternative buffering agents. This parameter change maintains the necessary pH control and deposition performance while eliminating the environmental toxicity associated with boric acid
3Productivity
If copper thickness is reduced to follow Moore's law, then integration density is improved, but reliability deteriorates due to increased cracking susceptibility
Solution Approach 1:
The patent changes the material parameter from copper to nickel, which has fundamentally different mechanical properties including higher strength and lower ductility. This allows the interconnect to maintain reliability at reduced thicknesses by following different scaling laws, enabling continued integration density improvement without proportionally increasing cracking risk
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 solution enhances the reliability of microelectronic interconnects by using nickel, which is less prone to oxidation and cracking than copper, and eliminates the use of boric acid, while also effectively managing internal stress to achieve complete via fill.
Implementation Method 1
The present invention relates generally to a nickel electrodeposition composition and a process for via fill metallization
Data Source
AI summary
A nickel electrodeposition composition for via fill or barrier nickel interconnect fabrication comprising: (a) a source of nickel ions; (b) one or more polarizing additives; and (c) one or more depolarizing additives. The nickel electrodeposition composition may include various additives, including suitable acids, surfactants, buffers, and/or stress modifiers to produce bottom-up filling of vias and trenches.