CMP Polishing Composition for Fine-Pitch Tungsten Flatness
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Solution Overview
Problem
As semiconductor devices become more miniaturized and complex, the CMP process faces challenges in maintaining a sufficient polishing rate and speed while minimizing defects such as dishing or erosion, especially when polishing substrates with fine pitch tungsten pattern films.
Innovation Solution
A polishing composition for semiconductor processes is developed, which includes polishing particles, iron ions, and an iron ion stabilizer with two or more carboxyl groups. This composition promotes oxidation of tungsten, controls zeta potential, and stabilizes iron ions to improve polishing selectivity and reduce defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP slurry is used for polishing substrates with fine pitch tungsten pattern films, then polishing rate can be maintained, but dishing and erosion defects occur frequently
Solution Approach 1:
The patent modifies the chemical composition parameters of the CMP slurry by incorporating iron ions (Fe2+ or Fe3+) at controlled concentrations (10-1000 ppm) along with specific chelating agents and pH buffers. This parameter change enables the slurry to achieve both high polishing rate and excellent surface flatness by controlling the chemical reactivity and mechanical removal characteristics during polishing
Solution Approach 2:
The patent creates a composite slurry system combining multiple components: iron ions, chelating agents (such as EDTA, citric acid, or gluconic acid), buffering agents, and conventional polishing particles. This composite formulation synergistically improves both polishing rate and surface flatness by distributing different functional roles among components, preventing dishing while maintaining efficient material removal
2Productivity
If polishing speed is increased to improve productivity, then polishing rate increases, but defects such as dishing and erosion worsen
Solution Approach 1:
The patent adjusts chemical parameters including iron ion concentration (10-1000 ppm), pH value (2-6 range), and chelating agent ratios to optimize the slurry's performance at higher polishing speeds. These parameter changes enable the slurry to maintain stable chemical-mechanical polishing action even at increased speeds, preventing dishing and erosion that typically worsen with speed increases
Solution Approach 2:
The iron ions act as intermediary species that mediate between the mechanical polishing action and the tungsten film. They form transient complexes with tungsten oxide during polishing, controlling the material removal rate and preventing excessive removal (erosion) and凹陷 (dishing) even when polishing speed is increased for higher productivity
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 polishing composition effectively smooths and defect-reduces the substrate surface, even with fine pitch tungsten pattern films, by enhancing polishing selectivity and preventing excessive polishing of insulating films, thus improving the overall CMP process efficiency.
Implementation Method 1
This polishing composition promotes oxidation of tungsten
Implementation Method 2
The iron ion stabilizer may include two or more carboxyl groups
Data Source
AI summary
Disclosed is a polishing composition for a semiconductor process, including polishing particles, iron ions, and an iron ion stabilizer, in which the iron ion stabilizer comprises two or more carboxyl groups and the polishing composition has electrical conductivity of 200 μS/cm to 800 μS/cm. The polishing composition may polish a substrate surface including a tungsten pattern film having a fine pitch more smoothly.