CMP Slurry Composition for Copper Polishing Defect Reduction
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Solution Overview
Problem
The CMP process for polishing copper layers in semiconductor fabrication often results in severe surface defects such as erosion and dishing, requiring a composition that can improve polishing rate and flatness while minimizing defects.
Innovation Solution
A CMP slurry composition comprising polishing particles, an oxidant, a complexing agent with a specific ratio of organic acid to glycine, a corrosion inhibitor, and deionized water, which includes surfactants, polymeric compounds, and pH regulators, optimized to reduce surface defects and enhance polishing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP slurry composition is used for polishing copper, then polishing action is achieved, but severe surface defects such as erosion and dishing occur
Solution Approach 1:
The patent changes the chemical parameters of the slurry by introducing a specific complexing agent system (organic acid + glycine) with controlled weight ratios (1:13 to 1:260). This chemical parameter change modifies the interaction between slurry and copper surface, reducing harmful oxidation and corrosion while maintaining polishing effectiveness, thereby reducing surface defects like erosion and dishing
Solution Approach 2:
The complexing agent acts as an intermediary substance that mediates between the oxidant and the copper surface. It forms a protective complex with copper ions, preventing excessive corrosion and dishing while allowing controlled oxidation for polishing. This intermediary role reduces surface defects without sacrificing polishing action
2Productivity
If polishing rate is increased to reduce polishing time, then productivity improves, but surface defects increase
Solution Approach 1:
The patent optimizes chemical parameters by controlling the ratio of organic acid to glycine (1:13 to 1:260 by weight) and their concentrations (0.1-15 wt% complexing agent). This parameter optimization enables higher polishing rates through improved chemical reactivity while simultaneously controlling surface defect formation through balanced complexation chemistry
Solution Approach 2:
The complexing agent ensures continuous and stable chemical action during polishing by maintaining consistent copper ion complexation throughout the process. This continuous stable interaction prevents intermittent aggressive attacks that cause defects, enabling sustained high polishing rates with consistent surface quality
3Manufacturing precision
If corrosion inhibitor and complexing agent are introduced to reduce surface defects, then surface quality improves, but polishing rate decreases
Solution Approach 1:
The patent uses a composite complexing agent system combining organic acid and glycine in specific ratios. This composite approach synergistically enhances surface protection (reducing defects) while maintaining adequate polishing rate. The organic acid provides initial complexation and the glycine sustains it, creating a balanced system that addresses both surface quality and productivity
Solution Approach 2:
The patent optimizes the concentration parameters of the complexing agent (0.1-15 wt%) and the organic acid to glycine ratio (1:13 to 1:260) to achieve the best balance. By carefully tuning these parameters, the system maintains sufficient chemical reactivity for acceptable polishing rates while providing adequate surface protection to minimize defects
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 significantly reduces surface defects and improves polishing rate and flatness, achieving fewer than 1,200 defects and an LPC value of 23,000 or less on a 12-inch copper blanket wafer, with a polishing rate of 4,000 to 6,000 Å/min, effectively addressing the challenges of erosion and dishing.
Implementation Method 1
an oxidant removing a metal oxide by forming a passive layer on a surface of a metal film
Implementation Method 2
a complexing agent chelating the metal oxide oxidized by the oxidant
Implementation Method 3
a corrosion inhibitor preventing excessive corrosion by passivation
Implementation Method 4
mechanical polishing action by the polishing pad and a polishing agent of a polishing slurry composition
Data Source
AI summary
The present invention relates to a CMP slurry composition for polishing copper, comprising: polishing particles; a complexing agent; a corrosion inhibitor; and deionized water. The complexing agent comprises one or more organic acids selected from oxalic acid, malic acid, malonic acid, and formic acid, and glycine.