Polishing Composition for Aluminum and Titanium Damascene Structures
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Solution Overview
Problem
Current chemical-mechanical polishing compositions exhibit lower removal rates for aluminum compared to titanium, leading to overpolishing and dishing in aluminum damascene fabrication processes, necessitating improved compositions for effective polishing of aluminum and titanium layers.
Innovation Solution
A chemical-mechanical polishing composition comprising an abrasive, an oxidizing agent (such as peroxides, persulfates, or ferric salts), calcium ions, an organic carboxylic acid, and water, with a pH range of 1.5 to 7, is used to enhance the removal rates of both aluminum and titanium layers, thereby reducing dishing and erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high removal rate compositions are used for aluminum, then polishing speed is improved, but dishing and erosion increase
Solution Approach 1:
The patent carefully controls the concentration parameters of active ingredients to achieve optimal polishing performance. The oxidizing agents are used at specific ranges (0.1-5.0% potassium persulfate, 0.01-1.0% ammonium persulfate, or 1-10% hydrogen peroxide), calcium ions at 50-500 ppm, and organic carboxylic acids at 0.1-5.0%. These controlled parameter changes enable high removal rates while maintaining surface flatness and minimizing dishing and erosion through balanced chemical reactivity.
2Loss of time
If polishing composition removes aluminum at high rate, then process time is reduced, but selectivity between aluminum and titanium deteriorates
Solution Approach 1:
The patent achieves high selectivity between aluminum and titanium by carefully controlling the chemical composition parameters. The oxidizing agents (potassium persulfate, ammonium persulfate, or hydrogen peroxide) at specified concentrations, combined with calcium ions (50-500 ppm) and organic carboxylic acids (0.1-5.0%), create a chemical environment that preferentially reacts with aluminum while maintaining controlled titanium removal. This enables fast polishing with high material selectivity, reducing process time without sacrificing selectivity.
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 proposed composition achieves controlled removal rates for aluminum and titanium layers, minimizing overpolishing and dishing, and allows for efficient planarization of substrates with improved selectivity and reduced erosion.
Implementation Method 1
an oxidizing agent selected from the group consisting of peroxides, persulfates, ferric salts, and combinations thereof
Implementation Method 2
an abrasive
Data Source
AI summary
The invention provides a chemical-mechanical polishing composition for polishing a substrate. The polishing composition comprises an oxidizing agent, calcium ion, an organic carboxylic acid, and water, wherein the polishing composition has a pH of about 1.5 to about 7. The invention further provides a method of chemically-mechanically polishing a substrate with the aforementioned polishing composition.