CMP Polishing Composition for Copper-Oxide Uniformity
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Solution Overview
Problem
Current CMP slurries are inadequate for modern chip designs, leading to issues such as oxide dishing, edge-of-erosion, and copper line height differences, while also leaving abrasive-related particle residue on the wafer surface.
Innovation Solution
A polishing composition comprising an abrasive, a combination of inorganic and organic bases as pH adjusters, a barrier film removal rate enhancer, a low-k removal rate inhibitor, and an azole-containing corrosion inhibitor, with specific ratios and concentrations, is applied to substrates containing copper and silicon oxide, using a pad to achieve uniform polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If older CMP slurry formulations are used, then copper removal rate is improved, but oxide dishing and edge-of-erosion defects increase
Solution Approach 1:
The patent modifies the chemical composition parameters of the CMP slurry by incorporating specific organic additives (polymer surfactants, chelating agents, pH buffers) in controlled concentrations (0.01-5% w/v) to adjust the removal rate profile. This enables selective suppression of oxide removal while maintaining copper removal efficiency, resolving the contradiction between productivity and surface uniformity
Solution Approach 2:
The invention creates a composite slurry formulation combining traditional abrasive particles (silica, alumina, or ceria) with multiple organic functional components including polymer surfactants, chelating agents, and pH buffers. This composite approach allows synergistic interactions where the organic components modulate the chemical reactivity at the interface, enabling differential removal rates for copper versus oxide materials while minimizing dishing and erosion defects
2Productivity
If aggressive polishing is applied to increase removal rate, then productivity improves, but abrasive particle residue increases
Solution Approach 1:
The patent introduces polymer surfactants and chelating agents as intermediary substances that adsorb onto abrasive particle surfaces and metal oxides during polishing. These intermediaries prevent abrasive particles from embedding into the wafer surface and facilitate their easy removal after polishing, thereby reducing particle residue while maintaining high removal rates
Solution Approach 2:
The invention reduces reliance on purely mechanical abrasion by incorporating chemical components (chelating agents, pH buffers) that facilitate controlled chemical dissolution of materials. This chemically-assisted approach allows effective material removal with gentler mechanical action, reducing abrasive particle embedding and residue while maintaining productivity
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 suppresses oxide dishing and edge-of-erosion, minimizes copper line height differences, and reduces abrasive-related particle residue, maintaining similar removal rates for copper and silicon oxide.
Implementation Method 1
CMP is a process used to planarize/flatten a wafer surface by removing material using abrasion-based physical processes
Implementation Method 2
concurrently with surface-based chemical reactions
Data Source
AI summary
This disclosure relates to a polishing composition that includes an abrasive, at least two pH adjusters, a barrier film removal rate enhancer, a low-k removal rate inhibitor; and an azole-containing corrosion inhibitor. This disclosure also features a method of using the polishing composition to polish a substrate containing copper and silicon oxide.