Bimetallic CMP Composition for Tungsten–Molybdenum Corrosion Control
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Solution Overview
Problem
Conventional CMP compositions struggle to effectively polish both tungsten and molybdenum layers while inhibiting corrosion, particularly in bimetallic applications where galvanic coupling accelerates molybdenum corrosion.
Innovation Solution
A chemical mechanical polishing composition comprising an aqueous carrier, abrasive particles, an iron-containing accelerator, a stabilizer, a nitrogen-containing tungsten etch inhibitor, and a substituted piperazine compound, which suppresses corrosion and enhances polishing rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP compositions use hydrogen peroxide as oxidizer, then polishing capability is achieved, but molybdenum corrosion is accelerated
Solution Approach 1:
The patent introduces a corrosion inhibitor as an intermediary substance that mediates between the oxidizer (hydrogen peroxide) and the molybdenum substrate. This inhibitor selectively protects molybdenum from corrosion while allowing the polishing process to continue, thus resolving the contradiction between achieving polishing capability and preventing molybdenum corrosion.
Solution Approach 2:
The patent modifies the chemical parameters of the CMP composition by adjusting the concentration and type of corrosion inhibitors, pH levels, and oxidizer amounts. These parameter changes enable the composition to maintain polishing effectiveness while reducing molybdenum corrosion susceptibility, balancing the conflicting requirements.
2Adaptability or versatility
If conventional CMP compositions polish both tungsten and molybdenum, then versatility is achieved, but corrosion inhibition is insufficient in bimetallic applications
Solution Approach 1:
The patent applies local quality by using corrosion inhibitors that specifically target molybdenum protection while maintaining general polishing capability for both tungsten and molybdenum. The inhibitor formulation is designed to provide enhanced protection at the molybdenum-tungsten interface and on molybdenum surfaces, addressing the specific corrosion risks in bimetallic applications without compromising overall versatility.
Solution Approach 2:
The corrosion inhibitor acts as an intermediary that enables the simultaneous polishing of both metals while protecting the more susceptible molybdenum. This intermediary substance allows the CMP composition to maintain its dual-metal polishing capability while significantly improving reliability in bimetallic configurations.
3Reliability
If galvanic coupling is present in bimetallic structures, then electrical connectivity is achieved, but corrosion rate increases
Solution Approach 1:
The corrosion inhibitor serves as a protective intermediary that interferes with the galvanic coupling effect between tungsten and molybdenum. By introducing this chemical intermediary, the patent maintains the electrical connectivity required for device functionality while suppressing the electrochemical corrosion that would otherwise be accelerated by the bimetallic contact.
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
The composition achieves high polishing rates for both tungsten and molybdenum while significantly reducing corrosion, especially in bimetallic substrates.
Implementation Method 1
chemical mechanical polishing (CMP) compositions and methods for polishing (or planarizing) the surface of a substrate
Implementation Method 2
moving the polishing composition relative to the substrate, and abrading the substrate to remove molybdenum
Implementation Method 3
an iron-containing accelerator
Implementation Method 4
oxidizer (e.g., hydrogen peroxide)
Implementation Method 5
oxidizer (e.g., hydrogen peroxide)
Data Source
AI summary
A chemical mechanical polishing composition comprises, consists of, or consists essentially of a liquid carrier, abrasive particles dispersed in the liquid carrier, an iron-containing accelerator, a stabilizer bound to the iron-containing accelerator, at least one inhibitor of tungsten etching, the inhibitor of tungsten etching including at least one nitrogen containing group, and a substituted piperazine compound.