CMP Polishing Composition for Oxide-Nitride Selectivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional semiconductor CMP slurries face challenges in selectively polishing silicon oxide over silicon nitride with high material removal rates and low defectivity, particularly in shallow trench isolation processes, due to high silicon nitride removal rates and low selectivity between silicon oxide and silicon nitride.
Innovation Solution
The development of polishing compositions comprising a silica abrasive, a nitride removal rate reducing agent with a hydrophobic and hydrophilic portion separated by alkylene oxide groups, an acid or base, and optionally a metal corrosion inhibitor, which maintain a pH between 2 and 6.5, achieving a high selectivity ratio of silicon oxide to silicon nitride removal rates and minimizing silicon nitride erosion and dishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP slurry is used to polish silicon oxide, then material removal rate is achieved, but silicon nitride removal rate is also high resulting in low selectivity
Solution Approach 1:
The patent introduces an intermediary substance (surfactant or polymer) into the CMP slurry that selectively adsorbs onto silicon nitride surfaces. This intermediary layer acts as a protective barrier during polishing, reducing silicon nitride removal rate while maintaining silicon oxide removal rate, thereby achieving high selectivity (greater than 10:1) without compromising productivity
Solution Approach 2:
The patent modifies the chemical composition parameters of the CMP slurry by adding specific surfactants or polymers with controlled concentrations (0.01-10 wt%). This parameter change alters the chemical interaction between the slurry and different materials, enabling selective protection of silicon nitride while maintaining effective polishing of silicon oxide
2Productivity
If high material removal rate is achieved on silicon oxide, then polishing efficiency improves, but silicon nitride erosion increases
Solution Approach 1:
The surfactant or polymer intermediary selectively binds to silicon nitride surfaces, creating a protective interface that prevents direct contact between the abrasive particles and silicon nitride. This allows high polishing efficiency on silicon oxide while minimizing silicon nitride erosion to less than 10 nm
Solution Approach 2:
The patent converts the potentially harmful effect of aggressive polishing chemicals into a beneficial selective protection mechanism. The same chemical environment that enables high silicon oxide removal rates inadvertently promotes surfactant adsorption on silicon nitride, which then protects it from erosion
3Speed
If conventional polishing composition is used, then polishing speed is maintained, but defectivity increases on silicon nitride
Solution Approach 1:
The added surfactant or polymer forms a protective intermediary layer on silicon nitride that prevents abrasive particle embedding and reduces surface defect formation. This allows maintenance of high polishing speed while reducing defectivity to less than 1 defect per 25mm x 25mm area
Solution Approach 2:
The patent adjusts the chemical parameters of the polishing composition by introducing specific concentrations of surfactants (0.01-10 wt%), which modifies the friction and adhesion characteristics at the polishing interface, enabling high-speed polishing with reduced defect generation
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
These compositions achieve low silicon nitride removal rates, minimal erosion, and low defectivity, with stable performance across various polish conditions and substrates, enhancing device yield and topography in semiconductor manufacturing.
Implementation Method 1
a nitride removal rate reducing agent comprising a hydrophobic portion containing a C4 to C40 hydrocarbon group; and a hydrophilic portion containing at least one group selected from the group consisting of a sulfinite group, a sulfate group, a sulfonate group, a carboxylate group, a phosphate group, and a phosphonate group
Data Source
AI summary
This disclosure relates to a polishing composition that includes at least one abrasive; at least one nitride removal rate reducing agent, an acid or a base; and water. The at least one nitride removal rate reduce agent can include a hydrophobic portion containing a C4 to C40 hydrocarbon group; and a hydrophilic portion containing at least one group selected from the group consisting of a sulfinite group, a sulfate group, a sulfonate group, a carboxylate group, a phosphate group, and a phosphonate group; in which the hydrophobic portion and the hydrophilic portion are separated by zero to ten alkylene oxide groups. The polishing composition can have a pH of from about 2 to about 6.5.