Polishing Composition for Selective Silicon Oxide Removal
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Solution Overview
Problem
Conventional CMP slurries face challenges in achieving high selectivity for silicon oxide removal over silicon nitride, often resulting in excessive silicon nitride removal and low device yields, especially in advanced semiconductor manufacturing where high-k metal gate and FinFET technologies are used.
Innovation Solution
Aqueous polishing compositions comprising an abrasive, a nitride removal rate reducing agent with a hydrophobic and hydrophilic portion separated by alkylene oxide groups, an acid or base, and water, with a pH range of 2 to 6.5, which selectively polish silicon oxide at high rates while minimizing silicon nitride removal, using colloidal silica as the abrasive to reduce defects and improve selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP slurries are used to remove silicon oxide, then material removal rate is improved, but silicon nitride removal increases excessively
Solution Approach 1:
The patent introduces a nitride removal rate reducing agent as an intermediary substance that selectively interacts with silicon nitride to suppress its removal, while allowing silicon oxide removal to proceed at high rates. This mediator enables independent control of the two material removal processes.
Solution Approach 2:
The patent modifies the chemical composition parameters of the CMP slurry by incorporating specific nitride removal rate reducing agents and adjusting pH levels to a specific range (2-6.5), thereby changing the chemical environment to achieve selective removal behavior.
2Reliability
If high selectivity for silicon oxide removal is achieved, then device yield is improved, but composition complexity increases
Solution Approach 1:
The patent creates a composite chemical system by combining multiple components: abrasive particles, nitride removal rate reducing agents, pH adjusters, and surfactants in specific concentrations, achieving complex functionality through controlled composition.
3Manufacturing precision
If silicon nitride removal rate is reduced, then selectivity is improved, but polishing performance decreases
Solution Approach 1:
The patent applies different chemical properties to different aspects of the polishing process: the abrasive provides mechanical removal capability while the nitride removal rate reducing agent provides selective chemical interaction, creating local functional differentiation within the slurry system.
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 compositions achieve a high selectivity ratio of silicon oxide to silicon nitride removal rates, minimizing silicon nitride erosion and dishing, leading to improved device yields and reduced defectivity on semiconductor substrates, suitable for both current and next-generation integration schemes.
Implementation Method 1
a nitride removal rate reducing agent comprising a hydrophobic portion and a hydrophilic portion
Implementation Method 2
at least one abrasive
Implementation Method 3
an acid or a base; and water, wherein the polishing composition has a pH of about 2 to about 6.5
Data Source
Figure 1(a)~1(d)
Figure 2
Figure 3
AI summary
This disclosure relates to a polishing composition that includes at least one abrasive; at least one nitride removal rate reducing agent, an acid or a base; and water. The at least one nitride removal rate reduce agent can include a hydrophobic portion containing a C12 to C40 hydrocarbon group; and a hydrophilic portion containing at least one group selected from the group consisting of a sulfinite group, a sulfate group, a sulfonate group, a carboxylate group, a phosphate group, and a phosphonate group; in which the hydrophobic portion and the hydrophilic portion are separated by zero to ten alkylene oxide groups. The polishing composition can have a pH of about 2 to about 6.5.