STI CMP Composition With Ceria-Coated Abrasives for Low SiN Loss
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Solution Overview
Problem
Existing Shallow Trench Isolation (STI) chemical mechanical polishing compositions fail to effectively reduce silicon nitride (SiN) film removal rates and oxide trench dishing, leading to non-uniform trench oxide loss across patterned wafers, which affects transistor performance and device fabrication yields.
Innovation Solution
The use of ceria-coated inorganic oxide abrasive particles combined with specific chemical additives, such as organic acetylenic molecules and polyols, in a CMP composition that suppresses SiN film removal rates and reduces oxide trench dishing, achieving high oxide vs nitride selectivity across various pH ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP compositions are used for STI planarization, then silicon dioxide removal rate is achieved, but silicon nitride film removal rate is too high and oxide trench dishing occurs
Solution Approach 1:
The patent modifies the chemical composition parameters of the CMP slurry by incorporating specific organic additives (polyols, carboxylic acids, or amines) that alter the chemical reactivity toward silicon nitride. These parameter changes suppress the SiN removal rate while maintaining SiO2 removal, achieving high selectivity and reducing trench dishing.
Solution Approach 2:
The patent introduces organic intermediary substances (polyols, carboxylic acids, or amines) that mediate the chemical interaction between the CMP slurry and the silicon nitride film. These intermediaries selectively inhibit the chemical reaction with SiN while allowing mechanical removal, thereby controlling the SiN removal rate without affecting SiO2 planarization.
2Manufacturing precision
If conventional CMP compositions are used for STI planarization, then silicon dioxide removal is achieved, but oxide trench dishing increases leading to non-uniform trench oxide loss
Solution Approach 1:
The patent changes the chemical parameters of the CMP composition by adding organic additives that modify the etch profile and removal uniformity. These parameter adjustments reduce the chemical component of dishing while maintaining overall planarization effectiveness, resulting in more uniform trench oxide loss across the wafer.
Solution Approach 2:
The organic intermediary substances (polyols, carboxylic acids, or amines) act as modifiers that control the chemical-mechanical interaction at the oxide-trench interface. They reduce excessive chemical etching in trench regions, thereby minimizing dishing and improving the uniformity of oxide removal across different trench areas.
3Productivity
If high oxide removal rate is achieved, then planarization efficiency is improved, but silicon nitride removal rate increases reducing selectivity
Solution Approach 1:
The patent optimizes the chemical composition parameters by incorporating organic additives that differentially affect the removal rates of SiO2 and SiN. These parameter changes enable high oxide removal rates to be maintained while selectively suppressing nitride removal, thereby achieving high selectivity ratios (e.g., 10:1 or higher).
Solution Approach 2:
The organic intermediary substances selectively modulate the chemical reactivity toward silicon nitride while having minimal impact on silicon dioxide removal. This selective mediation allows the CMP process to achieve high productivity for oxide removal while maintaining high selectivity, as the intermediaries specifically inhibit SiN chemical reaction pathways.
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 solution significantly reduces SiN film removal rates, increases oxide vs nitride selectivity, and minimizes oxide trench dishing, thereby improving the planarization of patterned wafers and preventing electrical current leakage between transistors.
Implementation Method 1
The present invention provides STI CMP polishing compositions for the suppressed SiN film removal rates and the increased removal selectivity of silicon oxide: silicon nitride
Implementation Method 2
chemical additives as SiN film removal rate suppressing agents
Implementation Method 3
increased removal selectivity of silicon oxide: silicon nitride
Data Source
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; chemical additive selected from the group consisting of an organic acetylene molecule containing an acetylene bond and at least two or multi ethoxylate functional groups with terminal hydroxyl groups, an organic molecule with at least two or multi hydroxyl functional groups in the same molecule, and combinations thereof; 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.