Acidic Onium Salt CMP Slurry for Silicon Dioxide Polishing
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Solution Overview
Problem
Conventional chemical-mechanical polishing (CMP) compositions exhibit unacceptable polishing rates for semiconductor materials like silicon dioxide, requiring the development of improved CMP compositions that enhance removal rates and selectivity.
Innovation Solution
A CMP composition with a pH of 5 or less, comprising colloidal silica and at least one onium salt, such as phosphonium or sulfonium salts, in combination with an aqueous carrier, which provides higher removal rates and improved stability for silicon dioxide polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP compositions are used, then the polishing process is simple and well-established, but the silicon dioxide removal rate is unacceptably low
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the CMP slurry. Specifically, it introduces onium salts (phosphonium, sulfonium, or ammonium salts) at controlled concentrations (0.01-10 wt%) combined with colloidal silica abrasives and adjusts the pH to acidic ranges (2-6). These parameter changes in composition chemistry directly enable significantly higher silicon dioxide removal rates while maintaining composition stability and polishing quality.
2Productivity
If higher concentrations of onium salts are used to increase removal rates, then polishing productivity improves, but composition stability and control deteriorate
Solution Approach 1:
The patent optimizes the concentration parameter of onium salts to a specific range (0.01-10 wt%, preferably 0.1-5 wt%). This parameter optimization achieves the balance between productivity and stability: sufficient onium salt concentration provides high removal rates through enhanced chemical activity, while maintaining stability by preventing excessive foaming, viscosity changes, or precipitation that would occur at higher concentrations.
Solution Approach 2:
The patent creates a composite CMP composition system combining multiple components with synergistic effects: onium salts (chemical activity enhancers), colloidal silica (abrasive particles), and acidic pH buffers. This composite formulation achieves stable high removal rates by distributing functions across components rather than relying on excessive concentrations of a single additive.
3Manufacturing precision
If conventional CMP compositions are used, then manufacturing costs are lower, but planarization efficiency and polishing quality are insufficient
Solution Approach 1:
The patent modifies several composition parameters simultaneously: introduces onium salts at optimized concentrations, adjusts pH to acidic ranges (2-6), and selects specific abrasive particle size distributions. These parameter changes collectively enhance planarization efficiency by improving chemical-mechanical interaction, while the use of commercially available onium salts and standard colloidal silica keeps manufacturing costs reasonable.
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 significantly higher silicon dioxide removal rates and superior planarization efficiency compared to conventional CMP compositions, with enhanced thermal and colloidal stability, particularly at low onium concentrations, offering economic benefits.
Implementation Method 1
The polishing of the substrate surface typically is further aided by the chemical activity of the polishing composition (e.g., by oxidizing agents or other additives present in the CMP composition)
Implementation Method 2
The relative movement of the pad and substrate serves to abrade the surface of the substrate to remove a portion of the material from the substrate surface
Implementation Method 3
The relative movement of the pad and substrate serves to abrade the surface of the substrate
Implementation Method 4
The polishing of the substrate surface typically is further aided by the chemical activity of the polishing composition (e.g., by oxidizing agents or other additives present in the CMP composition)
Data Source
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AI summary
The present invention provides a chemical-mechanical polishing (CMP) composition suitable for polishing semiconductor materials. The composition has a pH of 5 or less and comprises colloidal silica, at least one onium compound selected from the group consisting of a phosphonium salt, a sulfonium salt, and a combination thereof, and an aqueous carrier therefor; A CMP method for polishing a surface of a semiconductor material utilizing the composition is also disclosed.