CMP Polishing Composition for Ruthenium Selectivity and Copper Protection
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Solution Overview
Problem
Current CMP slurries struggle to effectively remove ruthenium and hard mask materials in semiconductor substrates without causing copper corrosion or defects, particularly in advanced BEOL applications where ruthenium is used as a liner material.
Innovation Solution
A polishing composition comprising an abrasive, pH adjuster, barrier film removal rate enhancer, low-k removal rate inhibitor, azole-containing corrosion inhibitor, and ruthenium removal rate enhancer, along with optional chelating and oxidizing agents, is used to minimize copper corrosion and achieve selective removal of ruthenium and hard mask materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional CMP slurries are used to polish ruthenium and copper substrates, then polishing can be performed, but copper corrosion occurs and unacceptable defects are caused
Solution Approach 1:
The polishing composition changes chemical parameters by incorporating specific corrosion inhibitors (azole compounds, DTA, DTPA) and pH adjusters to create a chemically selective environment that protects copper while enabling ruthenium removal. The composition includes corrosion inhibitors at concentrations of 0.0001-1% and pH adjusters to maintain optimal polishing conditions without causing copper corrosion.
Solution Approach 2:
The composition uses intermediary substances including corrosion inhibitors as mediators between the polishing abrasive and the copper substrate. These intermediaries (azole-containing corrosion inhibitors, DTA, DTPA) intercept and prevent direct harmful interaction between the polishing slurry and copper, while allowing the ruthenium removal process to proceed effectively.
2Manufacturing precision
If ruthenium removal is enhanced, then polishing selectivity improves, but copper corrosion increases
Solution Approach 1:
The polishing composition applies local quality by creating different chemical environments for different materials. The composition includes ruthenium removal rate enhancers that specifically target ruthenium, while simultaneously incorporating copper corrosion inhibitors that create a protective local environment for copper. This localized chemical selectivity allows enhanced ruthenium removal without proportional copper corrosion.
Solution Approach 2:
The polishing composition is a composite chemical system combining multiple functional components: abrasives, pH adjusters, barrier film removal rate enhancers, low-k removal rate inhibitors, azole-containing corrosion inhibitors, and ruthenium removal rate enhancers. This composite formulation achieves both high ruthenium removal selectivity and copper protection through synergistic interaction of multiple chemical agents.
3Length of moving object
If multilayer Cu/barrier/dielectric stacks are made thinner, then feature miniaturization is achieved, but resistivity increases exponentially
Solution Approach 1:
The polishing composition addresses this contradiction by removing barrier films (Ta/TaN) and ruthenium liners that contribute to interconnect resistance. By selectively removing these layers while preserving the copper conductive material, the composition enables thinner overall stack configurations that maintain acceptable resistivity levels, supporting continued feature miniaturization.
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 ruthenium and hard mask materials while minimizing copper corrosion, maintaining favorable removal rates and selectivity, suitable for advanced semiconductor fabrication processes.
Implementation Method 1
a polishing composition that includes an abrasive
Implementation Method 2
an azole-containing corrosion inhibitor
Implementation Method 3
a pH adjuster
Data Source
AI summary
A polishing composition, includes an abrasive; a pH adjuster; a barrier film removal rate enhancer; a low-k removal rate inhibitor; an azole-containing corrosion inhibitor; and a ruthenium removal rate enhancer. A method of polishing a substrate includes the steps of: applying the polishing composition described herein to a surface of a substrate, wherein the surface comprises ruthenium or a hard mask material; and bringing a pad into contact with the surface of the substrate and moving the pad in relation to the substrate.