CMP Slurry Composition for Copper Selectivity and Dishing Control
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Solution Overview
Problem
The copper chemical mechanical polishing process faces challenges in achieving high removal rates and selectivity for copper over tantalum barrier layers while minimizing copper dishing and dielectric erosion, with existing slurries often resulting in surface defects and residue due to uneven polishing pressures and strong chemical etching.
Innovation Solution
A chemical mechanical polishing slurry comprising silica abrasive particles with a wide size distribution, azole corrosion inhibitors without benzene, polyacrylic acid anionic surfactants, and an oxidizer, which improves copper removal selectivity over tantalum barrier layers and reduces dishing and dielectric erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the chemical effect of the copper polishing slurry is strengthened and the static etch rate is increased, then the copper removal rate is improved, but the passivation film on copper surface is easily removed even under low pressure, resulting in lower planarization efficiency and larger dishing
Solution Approach 1:
The patent modifies the chemical composition parameters of the polishing slurry by introducing a complexing agent that forms stable complexes with copper ions. This changes the chemical reaction mechanism to achieve high removal rates without excessive etching, resolving the contradiction between productivity and precision.
Solution Approach 2:
The patent introduces a complexing agent as an intermediary substance that mediates between the oxidizer and copper surface. This intermediary controls the chemical reaction to maintain passivation film integrity while enabling efficient copper removal, addressing both removal rate and dishing control requirements.
2Productivity
If the polishing pressure is increased to remove bulk copper, then the copper removal rate is improved, but the copper in the recess area experiences lower pressure and removes slower, resulting in uneven planarization
Solution Approach 1:
The patent replaces reliance on mechanical pressure differentiation with a chemically-driven removal mechanism. The complexing agent enables uniform chemical etching across the copper surface, allowing bulk removal without creating the pressure-dependent non-uniformity that plagues mechanical polishing alone.
3Use of energy by moving object
If the copper width is reduced to improve integration, then the energy consumption and delay time are decreased, but the mechanical strength of low-k dielectric layers is reduced and surface defects become more significant
Solution Approach 1:
The patent creates a highly controlled and reproducible polishing process that produces consistent, defect-free copper surfaces. This reliability enables the industry to confidently adopt narrower copper widths and low-k dielectrics, as the polishing process reliably removes surface defects that would otherwise compromise circuit stability.
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 slurry enhances copper removal rates while maintaining high selectivity and minimizing surface defects, ensuring effective planarization and reducing copper residue and corrosion after polishing.
Implementation Method 1
chemical mechanical polishing slurry comprises silica abrasive particles
Implementation Method 2
chemical mechanical polishing slurry comprises an oxidizer
Implementation Method 3
chemical mechanical polishing slurry comprises polyacrylic acid anionic surfactants
Implementation Method 4
chemical mechanical polishing slurry comprises azole corrosion inhibitors without benzene
Data Source
AI summary
The present invention discloses a chemical mechanical polishing slurry, the chemical mechanical polishing slurry comprises silica abrasive particles, a corrosion inhibitor, a complexing agent, an oxidizer, and at least one kind of polyacrylic acid anionic surfactant. The polishing slurry of the present invention can decrease the removal rate of tantalum while increasing the removal rate of copper, and reduce copper dishing and dielectric erosion after polish.