Ceria-Coated CMP Slurry for STI Trench Dishing Control
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Solution Overview
Problem
Existing Shallow Trench Isolation (STI) chemical mechanical polishing compositions fail to effectively reduce oxide trench dishing and achieve uniformity across various sized oxide trench features while maintaining high selectivity for silicon dioxide over silicon nitride, leading to potential electrical issues and device failure.
Innovation Solution
A chemical mechanical polishing composition using ceria-coated inorganic oxide particles combined with specific chemical additives, such as organic carboxylic acid molecules, carboxylate salts, or carboxylic ester molecules with multiple hydroxyl functional groups, which suppress SiN film removal rates and reduce oxide trench dishing, applied across a wide pH range including acidic, neutral, and alkaline conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional STI CMP compositions are used, then silicon dioxide removal rate is maintained, but oxide trench dishing is severe and non-uniform
Solution Approach 1:
The patent changes the chemical parameters of the CMP slurry by incorporating specific organic acids (polyacrylic acid, polymethacrylic acid, polyacrylic acid-co-maleic acid) and controlling pH levels (9-11) to modify the chemical interaction between slurry and oxide trench surfaces, reducing dishing while maintaining removal rates
Solution Approach 2:
The invention uses composite abrasive systems combining ceria particles with organic acid additives, creating a multi-functional slurry that simultaneously provides mechanical abrasion and chemical etching effects to achieve uniform trench planarization
2Manufacturing precision
If high oxide vs nitride selectivity is achieved, then silicon nitride removal is suppressed, but oxide trench dishing increases
Solution Approach 1:
The patent applies different chemical mechanisms to different regions: organic acids selectively interact with oxide surfaces in trenches to reduce dishing, while the slurry maintains high selectivity for oxide over nitride removal through controlled chemical affinity and pH conditions
Solution Approach 2:
Organic acid molecules act as intermediaries that mediate between the abrasive particles and the oxide surface, modifying the chemical interaction to reduce excessive oxide removal in trenches while maintaining overall selectivity
3Manufacturing precision
If polyacrylic acid is used to reduce oxide trench dishing, then dishing is reduced, but molecular weight control becomes critical for optimal performance
Solution Approach 1:
The patent specifies precise molecular weight ranges (300-20,000 for polyacrylic acid, 500-50,000 for polymethacrylic acid) to optimize the balance between dishing reduction effectiveness and slurry stability, recognizing that polymer chain length directly impacts interaction with oxide surfaces
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 achieves reduced oxide trench dishing, improved uniformity, and high oxide to nitride selectivity, preventing electrical current leakage and enhancing transistor performance by effectively suppressing SiN removal rates and maintaining high TEOS film removal rates.
Implementation Method 1
The slurry comprises cerium oxide particles and polymeric electrolyte
Implementation Method 2
chemical mechanical polishing compositions containing abrasive particles and exhibiting normal stress effects
Implementation Method 3
non-polishing particles resulting in reduced polishing rate at recesses
Implementation Method 4
polymeric electrolyte... salts of polyacrylic acid
Implementation Method 5
a compound which complexes with the silica and silicon nitride wherein the complexing agent has two or more functional groups each having a dissociable proton
Implementation Method 6
an aqueous medium... pH of 4 to 9
Implementation Method 7
aqueous medium, and an organic polyol that does not dissociate protons
Data Source
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AI summary
Present invention provides Chemical Mechanical Planarization Polishing(CMP) compositions for Shallow Trench Isolation(STI) applications. The CMP compositions contain ceria coated inorganic oxide particles as abrasives, such as ceria-coated silica particles or any other ceria-coated inorganic metal oxide particles as core particles; suitable chemical additives comprising at least one organic carboxylic acid group, at least one carboxylate salt group or at least one carboxylic ester group and two or more hydroxyl functional groups in the same molecule; and a water soluble solvent; and optionally biocide and pH adjuster; wherein the composition has a pH of 2 to 12, preferably 3 to 10, and more preferably 4 to 9.