Anionic Silica CMP Slurry for Tungsten Topography and EOE Control
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Solution Overview
Problem
Current chemical-mechanical polishing (CMP) slurries for tungsten and dielectric oxide films face challenges such as excessive edge-over-erosion (EOE), low film removal rates, and compromised topography performance, leading to yield loss and increased process times in semiconductor manufacturing.
Innovation Solution
A CMP composition comprising surface-modified colloidal silica particles with a negative charge, an iron compound, a stabilizing agent, a corrosion inhibitor, and an aqueous carrier, which provides improved topography performance and reduced EOE by optimizing the polishing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP slurries are used to achieve high tungsten removal rates, then film removal rate is improved, but edge-over-erosion (EOE) increases causing yield loss
Solution Approach 1:
The patent modifies the chemical composition parameters of the CMP slurry by incorporating specific additives (e.g., chelating agents, corrosion inhibitors, pH buffers) to alter the chemical reactivity profile. This enables high tungsten removal rates while suppressing excessive oxide erosion at pattern edges, thus resolving the contradiction between productivity and manufacturing precision
Solution Approach 2:
The invention uses a composite slurry formulation combining multiple components including abrasive particles, chemical additives, and stabilizers. This composite approach allows simultaneous optimization of tungsten removal (via abrasive and chemical action) and EOE control (via protective chemical agents that selectively inhibit oxide erosion at edges)
2Manufacturing precision
If CMP slurry formulation is optimized for low EOE, then manufacturing precision is improved, but film removal rate decreases increasing process times
Solution Approach 1:
The patent adjusts chemical parameters including pH level, additive concentrations, and redox potential to create a balanced chemical environment. This enables effective tungsten removal at reduced process times while maintaining low EOE through selective chemical inhibition of oxide erosion, thus resolving the contradiction between manufacturing precision and loss of time
Solution Approach 2:
The invention introduces intermediary chemical substances (chelating agents, corrosion inhibitors) that mediate between the abrasive particles and the substrate. These intermediaries facilitate efficient tungsten removal while protecting oxide regions from excessive erosion, enabling both fast processing and high precision topography control
3Reliability
If anionic silicas are used to improve defectivity and colloidal stability, then reliability is improved, but film removal rate and pattern performance deteriorate
Solution Approach 1:
The patent creates a composite slurry system that combines anionic silica particles with complementary cationic or neutral additives. This composite formulation maintains the colloidal stability and defectivity improvements from anionic silicas while adding components that enhance tungsten removal rate and pattern performance, thus resolving the contradiction between reliability and productivity
Solution Approach 2:
The invention develops a multi-functional slurry formulation where the additive package serves multiple purposes: maintaining colloidal stability (from anionic silica), enhancing tungsten removal (via chelating agents and pH control), and improving pattern performance (via EOE suppression). This multi-functionality resolves the contradiction by making the system simultaneously achieve reliability and productivity goals
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 solution achieves enhanced tungsten and dielectric oxide removal rates with reduced EOE and improved planarization efficiency, leading to higher quality semiconductor devices and increased throughput.
Implementation Method 1
The polishing of the substrate typically is further aided by the chemical activity of the polishing composition and/or the mechanical activity of an abrasive suspended in the polishing composition
Implementation Method 2
CMP utilizes a chemical composition, known as a CMP composition or more simply as a polishing composition (also referred to as a polishing slurry), for selective removal of material from the substrate
Data Source
AI summary
The invention provides a chemical-mechanical polishing composition comprising a) surface-modified colloidal silica particles, comprising a negatively-charged group on the surface of the particles, wherein the surface-modified colloidal silica particles have a negative charge, a particle size of about 90 nm to about 350 nm, and a zeta potential of about -5 mV to about -35 mV at a pH of about 3, b) an iron compound, c) a stabilizing agent, d) a corrosion inhibitor, and e) an aqueous carrier. The invention also provides a method suitable for polishing a substrate.