CMP Slurry Chemistry for Tungsten Polishing With Lower Corrosion
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Solution Overview
Problem
Conventional chemical mechanical polishing (CMP) compositions face challenges in effectively polishing tungsten and molybdenum layers without causing corrosion, especially in advanced node semiconductor devices where feature sizes are extremely small.
Innovation Solution
A water-based CMP composition comprising abrasive particles, an amino acid selected from arginine, histidine, cysteine, lysine, and mixtures thereof, and an anionic polymer or anionic surfactant, which provides improved inhibition of corrosion and etching while achieving high removal rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP compositions use hydrogen peroxide as oxidizer to achieve high removal rates, then polishing efficiency is improved, but corrosion of tungsten and molybdenum layers increases
Solution Approach 1:
The invention changes the chemical parameters of the CMP composition by introducing amino acids (which interact with metal surfaces through chelation and adsorption) and anionic polymers/surfactants (which provide electrostatic repulsion and surface passivation). These parameter changes modify the chemical environment to reduce corrosion while maintaining removal rate, directly resolving the contradiction between high productivity and low corrosion.
Solution Approach 2:
Amino acids act as intermediary substances between the oxidizer and the metal surface. They form protective complexes with tungsten and molybdenum, mediating the interaction to prevent direct aggressive attack by hydrogen peroxide while still allowing controlled oxidation for material removal. This intermediary mechanism reduces corrosion without sacrificing polishing efficiency.
2Productivity
If CMP composition uses aggressive oxidizing agents to increase removal rate, then polishing productivity is improved, but etching of metal layers worsens
Solution Approach 1:
The invention modifies the chemical parameters by adding amino acids and anionic polymers that adjust the oxidizing environment. These additives change the reaction kinetics and selectivity, enabling high removal rates while improving etching control through selective passivation of metal surfaces.
Solution Approach 2:
The invention converts the potentially harmful aggressive oxidation into a beneficial selective process. The amino acids and anionic polymers direct the oxidizing action preferentially toward material removal while protecting against unwanted etching, turning the harmful aggressiveness into a controlled and beneficial effect for achieving both high productivity and precision.
3Productivity
If CMP slurry uses strong oxidizers to achieve effective metal removal, then polishing efficiency is improved, but susceptibility to corrosion in advanced node devices increases
Solution Approach 1:
Amino acids serve as intermediary protective agents that form stable complexes with metal surfaces during CMP. These intermediaries shield the metal from direct exposure to strong oxidizers, maintaining removal efficiency while significantly improving corrosion resistance and reliability for advanced node devices with extremely small feature sizes.
Solution Approach 2:
The CMP composition is formulated as a composite system combining oxidizers, amino acids, and anionic polymers/surfactants. This composite approach creates a synergistic effect where each component contributes specific functions: oxidizers provide removal power, amino acids provide corrosion protection through chelation, and anionic polymers provide additional surface passivation. Together, they achieve both high productivity and high 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 composition effectively polishes tungsten and molybdenum layers with reduced corrosion and etching rates, enabling efficient planarization of substrates 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
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 3
abrading the substrate to remove a portion of the molybdenum layer from the substrate
Implementation Method 4
abrading the substrate to remove a portion of the molybdenum layer from the substrate
Implementation Method 5
Chemical mechanical polishing compositions commonly employ an oxidizer such as hydrogen peroxide that can be chemically aggressive to the polished metal
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.