Titanium CMP Slurry Using Colloidal Silica at Low pH
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Solution Overview
Problem
Conventional polishing compositions for semiconductor devices are unable to efficiently polish titanium barrier layers at high stock removal rates and often cause safety issues and metallic contamination due to the use of fluoride and metallic catalysts, requiring multiple compositions for different steps, which decreases working efficiency.
Innovation Solution
A polishing composition containing more than 0.1% by mass of colloidal silica and water, with a pH of 6 or less, is used to effectively polish titanium-containing objects, utilizing colloidal silica and an oxidizing agent like periodic acid to enhance polishing efficiency and prevent erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polishing compositions are used, then safety and contamination issues are avoided by not using fluoride and metallic catalysts, but the stock removal rate for titanium barrier layers is low
Solution Approach 1:
The patent changes the chemical composition parameters of the polishing slurry by using colloidal silica particles with specific size ranges (0.5-10 micrometers) and controlling pH levels, replacing conventional fluoride-based and metallic catalyst-containing compositions. This parameter change enables high stock removal rates for titanium while eliminating safety and contamination issues.
Solution Approach 2:
The invention creates a composite polishing system combining colloidal silica particles, oxidizing agents (such as periodic acid or ammonium persulfate), and specific pH buffers. This composite material achieves both high productivity in titanium polishing and eliminates harmful factors through the synergistic interaction of its components.
2Manufacturing precision
If multiple polishing compositions are used for different steps, then polishing precision is improved, but working efficiency decreases due to the need to provide and replace multiple compositions
Solution Approach 1:
The patent develops a universal polishing composition that can perform multiple polishing functions in a single step. The slurry with colloidal silica and oxidizing agents can simultaneously polish both conductor layers (aluminum, copper, tungsten) and barrier layers (titanium, titanium nitride) with appropriate precision, eliminating the need for multiple specialized compositions and improving working efficiency.
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 allows for high stock removal rates of both titanium barrier and conductor layers, reducing the need for multiple polishing compositions and enhancing working efficiency by promoting mechanical polishing while minimizing erosion and contamination risks.
Implementation Method 1
The polishing composition includes more than 0.1% by mass of colloidal silica... promoting mechanical polishing
Implementation Method 2
utilizing colloidal silica and an oxidizing agent like periodic acid to enhance polishing efficiency
Data Source
AI summary
A polishing composition includes more than 0.1% by mass of colloidal silica, and water, and has a pH of 6 or less. The polishing composition has the ability to polish a titanium material at a high stock removal rate. Thus, the polishing composition is suitable for use in applications for polishing a titanium-containing object.