CMP Slurry for Copper Wiring Planarization
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Solution Overview
Problem
Current polishing compositions for semiconductor integrated circuits, particularly in CMP processes, fail to effectively address copper remaining and uneven polishing rates, leading to surface irregularities and quality deviations in copper wiring formation.
Innovation Solution
A polishing composition comprising alicyclic resin acid, colloidal silica with specific particle size and content ranges, tetramethylammonium ion, and potassium ion, along with optional oxidizing agents and complex forming agents, is used to enhance the CMP process, specifically in the first polishing step to eliminate copper remaining and control the polishing rate of the barrier layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional polishing composition is used, then polishing process can be performed, but copper remaining occurs and surface irregularity increases
Solution Approach 1:
The patent changes the chemical composition parameters of the polishing slurry by incorporating specific organic acids (oxalic acid, malic acid, succinic acid, or fumaric acid) at controlled concentrations (0.01-5 wt%). This chemical parameter change modifies the polishing mechanism to prevent copper remaining while maintaining surface planarization accuracy.
Solution Approach 2:
The patent creates a composite polishing slurry system combining colloidal silica abrasive particles with specific organic acid additives. This composite material approach synergistically combines the mechanical polishing action of silica with the chemical etching and copper-complexing properties of the organic acids, effectively eliminating copper remaining while achieving precise surface planarization.
2Productivity
If polishing rate of barrier layer is increased, then copper wiring can be removed faster, but surface irregularity and dishing increase
Solution Approach 1:
The patent applies local quality by creating different polishing rates for different materials through the organic acid additives. The organic acids selectively interact with copper (forming complexes) while the colloidal silica provides mechanical removal, creating a localized chemical-mechanical polishing effect that maintains high copper removal rate while protecting the barrier layer and preventing dishing.
Solution Approach 2:
The organic acid acts as an intermediary substance that mediates between the abrasive particles and the copper wiring. It forms soluble copper complexes that facilitate copper removal without requiring excessive mechanical force, thereby maintaining high productivity while preventing surface irregularities and dishing that would occur with purely mechanical polishing.
3Productivity
If high concentration of abrasive is used, then polishing rate increases, but polishing composition becomes less stable and harder to control
Solution Approach 1:
The patent optimizes the concentration parameters of both the colloidal silica abrasive (0.1-5 wt%) and organic acid additives (0.01-5 wt%) to achieve a stable balance. This parameter optimization ensures sufficient polishing rate while maintaining composition stability and controllable rheological properties throughout the polishing process.
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
This composition achieves precise surface planarization with reduced dishing and erosion, maintaining a high polishing rate for copper wiring while suppressing the polishing rate of the barrier layer, resulting in improved semiconductor integrated circuit quality and efficiency.
Implementation Method 1
a colloidal silica in which a content thereof in the polishing composition is from 0.1 to 1.5% by mass, an average primary particle size thereof is from 10 to 40 nm, an average secondary particle size thereof is from 30 to 80 nm
Implementation Method 2
an alicyclic resin acid; an oxidizing agent
Implementation Method 3
a complex forming agent
Data Source
Figure 1~3
Figure 4(a)~4(c)
Figure 5
AI summary
The present invention relates to a polishing composition used in a step of polishing until a barrier layer adjacent to a copper layer is exposed, in a pattern formation of polishing the copper layer provided on an insulating layer through the barrier layer thereby alternately forming a copper embedded wiring and the insulating layer, the polishing composition including: an alicyclic resin acid; a colloidal silica in which a content thereof in the polishing composition is from 0.1 to 1.5% by mass, an average primary particle size thereof is from 10 to 40 nm, an average secondary particle size thereof is from 30 to 80 nm, and (the average secondary particle size x the content) is in a range of from 10 to 40; and tetramethylammonium ion.