STI CMP Slurry Composition for Low Oxide Trench Dishing
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Solution Overview
Problem
Existing chemical mechanical polishing (CMP) compositions for Shallow Trench Isolation (STI) processes fail to effectively reduce oxide trench dishing and improve polishing window stability, leading to poor transistor isolation and device failure.
Innovation Solution
A CMP composition using a combination of inorganic oxide particles and three specific chemical additives, including organic polymers with multiple hydroxyl groups, carboxylic acid-containing polymers, and polyethylene glycol, to suppress silicon nitride and polysilicon removal rates, thereby enhancing the selectivity of oxide to silicon nitride and polysilicon while reducing oxide trench dishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP compositions are used for STI polishing, then oxide removal rate is achieved, but oxide trench dishing increases leading to poor transistor isolation
Solution Approach 1:
The patent modifies the chemical composition parameters of the CMP slurry by incorporating specific organic polymers with carboxylic acid groups (such as polyacrylic acid, polyacrylamide carboxylate) and polyhydroxy compounds (such as sorbitol, mannitol, sucrose). These parameter changes in chemical composition enable selective suppression of oxide removal in trench regions while maintaining overall polishing effectiveness, thereby reducing oxide trench dishing and improving transistor isolation quality
Solution Approach 2:
The patent employs a composite polishing composition that combines inorganic abrasive particles with multiple organic polymer additives having specific functional groups. This composite material approach creates synergistic effects where the organic polymers modify the chemical-mechanical interaction at the polishing interface, enabling differential removal rates between trench oxide and blanket oxide, thus reducing dishing while maintaining reliability
2Productivity
If high oxide removal rate is achieved, then polishing efficiency improves, but selectivity between oxide and silicon nitride decreases
Solution Approach 1:
The patent adjusts chemical parameters by introducing organic polymers with carboxylic acid groups and polyhydroxy compounds that selectively interact with oxide surfaces. These parameter modifications enable the slurry to maintain high oxide removal rates through enhanced chemical affinity while simultaneously preserving selectivity by controlling the rate differential between oxide and silicon nitride removal through the specific chemical properties of the added polymers
3Shape
If polishing is performed to achieve planarization, then surface flatness improves, but non-uniform oxide loss across die occurs affecting transistor performance
Solution Approach 1:
The patent applies local quality control by using organic polymer additives that create spatially differentiated removal rates across the wafer surface. The polymers with carboxylic acid and polyhydroxy groups preferentially interact with oxide in trench regions versus blanket oxide regions, enabling local suppression of dishing while maintaining overall planarization, thus achieving both surface flatness and uniform oxide loss across the die
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 high removal selectivity of oxide to silicon nitride and polysilicon, significantly reducing oxide trench dishing and improving polishing window stability, leading to improved transistor performance and device yield.
Implementation Method 1
abrasive particles
Implementation Method 2
chemical additives, including organic polymers with multiple hydroxyl groups, carboxylic acid-containing polymers, and polyethylene glycol
Data Source
AI summary
The present invention discloses Shallow Trench Isolation (STI) Chemical Mechanical Planarization (CMP) polishing compositions, methods and systems that offer high and tunable Oxide: SiN and Oxide: Poly-Si removal selectivity, and low oxide trench dishing at different pH conditions in addition to suppressed Poly-Si removal rates. The polishing compositions comprise abrasive particles such as calcined ceria, and at least two preferably at least three chemical additives. The additives are (1) chemicals such as D-mannose, L-mannose, ribitol (D-ribitol), xylitol, meso-erythritol, D-sorbitol, mannitol, dulcitol, iditol, maltitol, fructose, sorbitan, sucrose, D-ribose, inositol, and glucose; (2) polyacrylic acid or polyacrylate and its ammonium, potassium or sodium salt, and (3) polyethylene glycol (PEG) with different molecular weight distributions as film selectivity tuning and oxide trench dishing reducing additives.