CMP Silica Slurry Particle Distribution for Tungsten Selectivity
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Solution Overview
Problem
Existing polishing liquids for chemical mechanical polishing (CMP) struggle to achieve a high polishing rate for tungsten materials while maintaining high selectivity with respect to insulating materials, leading to issues with flatness and insulation properties in semiconductor manufacturing.
Innovation Solution
A polishing liquid containing abrasive grains with specific particle size distribution (D50 ≤ 150 nm, D90 ≥ 100 nm, and D90 - D50 ≥ 21 nm) and a silica content of 1.0% by mass, along with optional additives like hydrogen peroxide, iron ion suppliers, organic acids, and anticorrosive agents, to enhance polishing rates and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polishing liquids are used to increase the polishing rate of tungsten material, then the polishing rate improves, but the selectivity with respect to insulating material deteriorates
Solution Approach 1:
The invention changes the particle size distribution parameters of abrasive grains, specifically setting D50 to 150 nm or less, D90 to 100 nm or more, and the difference (D90-D50) to 21 nm or more. This precise parameter control enables the polishing liquid to achieve high polishing rate for tungsten material while maintaining high selectivity against insulating material, resolving the technical contradiction between productivity and manufacturing precision.
Solution Approach 2:
The invention uses composite abrasive grains consisting of silica particles with specific size distribution combined with a carefully formulated liquid medium containing multiple additives (oxidizing agents, complexing agents, surfactants). This composite structure enables the polishing liquid to simultaneously achieve high polishing rate and high selectivity by combining the mechanical action of appropriately sized particles with chemical effects that preferentially affect tungsten over insulating materials.
2Productivity
If the polishing rate of tungsten material is increased, then throughput improves, but the flatness in subsequent polishing steps deteriorates
Solution Approach 1:
By precisely controlling the particle size distribution parameters (D50 ≤ 150 nm, D90 ≥ 100 nm, D90-D50 ≥ 21 nm), the invention achieves a balanced polishing action that removes tungsten material efficiently while maintaining surface flatness. The specific size distribution ensures that particles are small enough to avoid creating large surface irregularities but large enough to provide effective polishing action, thus resolving the contradiction between throughput and surface flatness.
3Productivity
If the polishing rate of insulating material is increased, then the polishing process becomes faster, but the insulation properties deteriorate
Solution Approach 1:
The invention changes the particle size distribution to achieve high selectivity, where the specific range (D50 ≤ 150 nm, D90 ≥ 100 nm, D90-D50 ≥ 21 nm) creates a polishing liquid that preferentially removes tungsten material while minimizing removal of insulating material. This selective action maintains insulation properties while still achieving high polishing rates for the target material.
Solution Approach 2:
The composite formulation combining silica particles of specific size distribution with chemical additives creates a polishing liquid that exhibits selective chemical-mechanical action. The chemical components enhance the difference in reactivity between tungsten and insulating materials, allowing the polishing process to favor tungsten removal while preserving the insulating film integrity, thus maintaining 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 solution enables efficient polishing of tungsten materials with high selectivity to insulating materials, improving throughput and maintaining surface flatness, while avoiding defects and extending the liquid's storage stability.
Implementation Method 1
a polishing liquid for CMP, containing: abrasive grains containing silica
Implementation Method 2
in a particle size distribution on mass basis obtained by a centrifugation method
Data Source
AI summary
A polishing liquid for CMP, containing: abrasive grains containing silica; and a liquid medium, in which a content of the abrasive grains is 1.0% by mass or more based on the total amount of the polishing liquid, and in a particle size distribution on mass basis obtained by a centrifugation method, D50 of the abrasive grains is 150 nm or less, D90 of the abrasive grains is 100 nm or more, and a difference between the D90 and the D50 is 21 nm or more.