CMP Slurry for ITO Polishing with Oxidizing Agents
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Solution Overview
Problem
Current chemical mechanical polishing (CMP) technologies face challenges in achieving high polishing rates and selectivity for indium tin oxide (ITO) layers, which are essential for advanced semiconductor devices with increasing integration density and multi-layered circuitry, due to the hard properties of ITO and the need for precise control over etching and polishing processes.
Innovation Solution
A CMP slurry composition comprising polishing particles, a dispersing agent, an auxiliary oxidizing agent, and a sugar alcohol compound is used to polish ITO layers, optimizing the polishing process by enhancing selectivity and preventing excessive etching of polishing stop layers, thereby improving surface uniformity and pattern distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP slurry is used to polish ITO layer, then polishing process can be performed, but polishing rate is low and polishing selectivity with respect to polishing stop layer is insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the CMP slurry by incorporating specific oxidizing agents (potassium permanganate, sodium chlorite, calcium hypochlorite, or sodium hypochlorite) at controlled concentrations (0.1-5 wt%). This chemical parameter modification enables simultaneous achievement of high polishing rate (300-500 nm/min for ITO) and high polishing selectivity (30:1 to 120:1 with respect to polishing stop layer), resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The patent creates a composite CMP slurry system combining polishing particles (colloidal silica or ceria) with specific oxidizing agents and sugar alcohol compounds. This composite formulation synergistically enhances both mechanical removal (polishing rate) and chemical selectivity (polishing selectivity), allowing the slurry to efficiently polish ITO while preserving the polishing stop layer, thus resolving the contradiction between high productivity and high manufacturing precision.
2Productivity
If polishing conditions are intensified to increase polishing rate, then productivity improves, but excessive etching of polishing stop layer occurs
Solution Approach 1:
The patent converts the potentially harmful excessive etching effect into a beneficial selective polishing process by using controlled oxidizing agents. The oxidizing agents (potassium permanganate, sodium chlorite, calcium hypochlorite, or sodium hypochlorite) selectively oxidize and soften the ITO layer for efficient removal, while the polishing particles mechanically remove the oxidized ITO material. This controlled chemical-mechanical process eliminates harmful etching of the polishing stop layer while maintaining high polishing rate, achieving 30:1 to 120:1 selectivity.
Solution Approach 2:
The patent modifies the chemical environment parameters by introducing specific oxidizing agents at optimized concentrations (0.1-5 wt%) and controlling pH (2-7) and sugar alcohol content (0.1-20 wt%). These parameter changes create a controlled chemical reaction that enhances ITO removal rate while preventing damage to the polishing stop layer, thus converting potential harmful etching into beneficial selective polishing.
3Manufacturing precision
If polishing is performed to achieve high selectivity, then polishing stop layer integrity is maintained, but surface uniformity and pattern distribution may be compromised
Solution Approach 1:
The patent partially replaces pure mechanical polishing with a chemical-mechanical process. The oxidizing agents chemically modify the ITO surface, softening it and making it more susceptible to mechanical removal by polishing particles. This chemical pre-treatment ensures uniform polishing across the surface while maintaining high selectivity, as the chemical reaction occurs uniformly before mechanical removal, preventing pattern distribution issues.
Solution Approach 2:
The patent optimizes multiple slurry parameters simultaneously: oxidizing agent concentration (0.1-5 wt%), pH (2-7), sugar alcohol content (0.1-20 wt%), and polishing particle size (0.1-10 μm). This multi-parameter optimization ensures that the chemical reaction proceeds uniformly across the ITO surface, producing consistent surface uniformity (RMS roughness < 1 nm) while maintaining high polishing selectivity (30:1 to 120:1), thus resolving the contradiction between manufacturing precision and reliability.
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 CMP slurry composition enables efficient polishing of ITO layers with high selectivity (30:1 to 120:1) relative to polishing stop layers, maintaining the integrity of stop layers and ensuring uniformity in surface roughness and layer thickness, thus simplifying semiconductor device fabrication and reducing process failures.
Implementation Method 1
an auxiliary oxidizing agent
Implementation Method 2
a polishing particle
Implementation Method 3
a dispersing agent
Data Source
AI summary
Described herein are chemical mechanical polishing (CMP) slurry compositions, such as CMP slurry compositions for polishing an indium tin oxide (ITO) layer, along with methods of fabricating a semiconductor device using such a CMP slurry composition. The CMP slurry composition can include a polishing particle, a dispersing agent, an auxiliary oxidizing agent, and a sugar alcohol compound.