CMP Slurry Composition for High-Rate Tungsten Polishing
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Solution Overview
Problem
Conventional chemical mechanical polishing (CMP) slurries face challenges in effectively removing tungsten and molybdenum layers while preventing corrosion, especially in advanced node semiconductor devices with small feature sizes.
Innovation Solution
A water-based CMP composition comprising abrasive particles, an amino acid (arginine, histidine, cysteine, or lysine), and an anionic polymer or surfactant, which reduces corrosion and enhances removal rates, suitable for tungsten and molybdenum layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP slurries use hydrogen peroxide as oxidizer to remove tungsten and molybdenum layers, then removal rate is improved, but corrosion susceptibility increases
Solution Approach 1:
The patent introduces amino acids (arginine, histidine, cysteine, or lysine) as intermediary substances that mediate between the oxidizer and the metal layers. These amino acids form protective complexes with tungsten and molybdenum, reducing direct corrosive attack by hydrogen peroxide while maintaining effective removal rates. The amino acids act as corrosion inhibitors that do not significantly reduce polishing performance.
Solution Approach 2:
The CMP slurry employs a composite chemical system combining hydrogen peroxide (oxidizer), amino acids (corrosion inhibitors), and anionic polymers or surfactants (additives). This composite formulation creates synergistic effects where the amino acids protect the metal surfaces from corrosion while the oxidizer maintains effective removal rates, resolving the contradiction between productivity and corrosion resistance.
2Productivity
If CMP slurry is made chemically aggressive to increase removal rate, then productivity is improved, but manufacturing precision deteriorates due to corrosion
Solution Approach 1:
The patent modifies the chemical parameters of the CMP slurry by incorporating amino acids at specific concentrations (0.01-1.0 M) and adjusting pH levels (1.0-5.0). These parameter changes create an optimized chemical environment where the slurry maintains high removal rates through controlled chemical aggression while the amino acids prevent excessive corrosion that would degrade planarization quality and manufacturing precision.
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 provides improved planarization and reduced corrosion of tungsten and molybdenum layers, enabling high removal rates with low etch rates, suitable for bulk and buff CMP operations in advanced node devices.
Implementation Method 1
an amino acid selected from the group consisting of arginine, histidine, cysteine, lysine, and mixtures thereof, and an anionic polymer or an anionic surfactant
Implementation Method 2
abrading the substrate to remove a portion of the molybdenum layer from the substrate and thereby polish the substrate
Implementation Method 3
abrasive particles dispersed in the liquid carrier
Data Source
AI summary
A chemical mechanical polishing composition for polishing tungsten or molybdenum comprises, consists essentially of, or consists of a water based liquid carrier, abrasive particles dispersed in the liquid carrier, an amino acid selected from the group consisting of arginine, histidine, cysteine, lysine, and mixtures thereof, an anionic polymer or an anionic surfactant, and an optional amino acid surfactant. A method for chemical mechanical polishing a substrate including a tungsten layer or a molybdenum layer includes contacting the substrate with the above described polishing composition, moving the polishing composition relative to the substrate, and abrading the substrate to remove a portion of the tungsten layer or the molybdenum layer from the substrate and thereby polish the substrate.