Tungsten Polishing Liquid Composition for Faster CMP Removal
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Solution Overview
Problem
The existing polishing liquids for tungsten materials in the damascene method require improvement in polishing rate to enhance process efficiency in semiconductor manufacturing.
Innovation Solution
A polishing liquid containing abrasive grains with a specific size range (40 to 140 nm) and silanol group density (8.0 groups/nm² or less) along with an iron-containing compound and an oxidizing agent, such as hydrogen peroxide, is used to achieve a superior polishing rate for tungsten materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polishing liquids are used for tungsten materials, then the polishing process can be completed, but the polishing rate is insufficient and process efficiency is low
Solution Approach 1:
The patent changes the chemical composition parameters of the polishing liquid by introducing specific oxidizing agents (potassium permanganate, sodium percarbonate, hydrogen peroxide) and controlling their concentrations (0.01-5% by mass), along with specific pH ranges (2-5), to achieve a polishing rate exceeding 350 nm/min for tungsten materials
Solution Approach 2:
The patent creates a composite polishing liquid system combining abrasive grains (colloidal silica with particle size 10-100 nm) and multiple chemical components (oxidizing agents, chelating agents like EDTA or citric acid, and buffering agents) that work synergistically to remove tungsten material at high rates while maintaining surface quality
2Manufacturing precision
If multiple polishing steps are used to achieve required surface quality, then surface flatness can be improved, but process complexity and cost increase
Solution Approach 1:
The patent develops a universal polishing liquid composition that performs multiple functions simultaneously: it provides high-rate tungsten removal, maintains surface flatness, and works across different polishing conditions, thereby eliminating the need for separate rough polishing and finish polishing steps with different chemistries
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 liquid enables tungsten materials to be polished at rates exceeding 350 nm/min, improving process efficiency and reducing the need for multiple polishing steps, thereby lowering costs and enhancing surface flatness.
Implementation Method 1
a polishing liquid containing abrasive grains with a specific size range (40 to 140 nm) and silanol group density (8.0 groups/nm² or less) along with an iron-containing compound and an oxidizing agent, such as hydrogen peroxide
Implementation Method 2
the polishing liquid containing abrasive grains, an iron-containing compound, and an oxidizing agent, in which the abrasive grains include silica particles
Data Source
AI summary
A polishing liquid for polishing a surface to be polished containing a tungsten material, the polishing liquid containing abrasive grains, an iron-containing compound, and an oxidizing agent, in which the abrasive grains include silica particles, an average particle diameter of the abrasive grains is 40 to 140 nm, and a silanol group density of the silica particles is 8.0 groups/nm2 or less. A polishing method of polishing a surface to be polished containing a tungsten material by using the polishing liquid.