CMP Polishing Composition for Ta/TEOS Selectivity and Cu Dishing Control
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Solution Overview
Problem
The challenge in semiconductor manufacturing is the selective polishing of materials like copper (Cu), tantalum (Ta), and SiO2 derived from tetraethylorthosilicate (TEOS) with high tantalum-to-TEOS removal rate selectivity and minimal copper loss, while addressing topography correction issues such as Cu dishing during chemical mechanical polishing (CMP).
Innovation Solution
A polishing composition comprising silica particles with specific size and surface modifications, a phosphate surfactant, a corrosion inhibitor, and a water-soluble polymer, formulated to achieve a pH of 7 to 11, which enhances the removal rates and selectivity of Cu, Ta, and TEOS, and corrects topography by minimizing Cu dishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polishing compositions are used to achieve high tantalum removal rates, then tantalum polishing efficiency is improved, but copper removal rates increase excessively causing material loss
Solution Approach 1:
The patent applies parameter changes by carefully controlling the pH of the polishing composition within a specific range (7-11) and using silica particles with controlled surface properties. This optimization allows achieving high tantalum removal rates while maintaining copper removal rates below 200 Å/min, thus resolving the contradiction between productivity and material loss.
2Productivity
If aggressive polishing conditions are applied to remove TEOS efficiently, then TEOS removal rate is improved, but tantalum-to-TEOS removal rate selectivity decreases
Solution Approach 1:
The patent achieves the desired selectivity (Ta/TEOS > 1.2) by optimizing chemical parameters including pH control (7-11) and using specific concentrations of additives such as phosphate surfactants (0.01-1.0 wt.%) and corrosion inhibitors (0.01-0.20 wt.%). These parameter adjustments enable efficient TEOS removal while maintaining high tantalum selectivity.
3Productivity
If high removal rates are achieved through increased polishing aggressiveness, then polishing productivity is improved, but topography correction deteriorates due to Cu dishing
Solution Approach 1:
The patent employs parameter changes including pH optimization (7-11), controlled silica particle size (30-80 nm average primary particle size), and addition of water-soluble polymers (0.01-0.50 wt.%) to achieve a balance between removal rate and topography correction. This reduces copper dishing while maintaining efficient polishing.
Solution Approach 2:
The patent introduces intermediary substances including phosphate surfactants, corrosion inhibitors (such as benzotriazole at 0.01-0.20 wt.%), and water-soluble polymers that act as mediators to control the polishing interaction. These intermediaries modulate the chemical-mechanical process to achieve both high productivity and good topography correction.
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 selective removal rates with Cu dishing correction, ensuring efficient polishing of Cu, Ta, and TEOS with improved topography, maintaining a tantalum-to-TEOS removal rate ratio greater than 1.2 and copper removal rates less than 200 Å/min.
Implementation Method 1
a phosphate surfactant
Implementation Method 2
a corrosion inhibitor
Implementation Method 3
an abrasive comprising silica particles
Implementation Method 4
a water-soluble polymer
Data Source
Figure 1A
Figure 1B~1D
Figure 1E~1F
AI summary
Polishing compositions and methods are provided which enable barrier polishing with tunable removal rate ratios for copper, tantalum, and TEOS. Polishing compositions comprising silica particles (greater than 12 nm), a metal corrosion inhibitor, and a phosphate surfactant are capable of achieving Ta to TEOS selectivities of greater than 1 and low Co removal rates (e.g., less than 200 Å/min), allowing for good topography correction (e.g., reduced dishing).