Titanium Oxide CMP Slurry for Selective Boron-Doped Polysilicon Polishing
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Solution Overview
Problem
There is a need for polishing compositions and methods that can achieve high removal rates and selectivity for boron-doped polysilicon and titanium nitride layers while maintaining low removal rates for silicon oxide and silicon nitride layers, which are commonly used in the fabrication of advanced node memory devices.
Innovation Solution
A chemical-mechanical polishing composition comprising a titanium oxide abrasive, an oxidizing agent, and water, with a pH of about 7 or less, is used to polish substrates. This composition effectively abrades boron-doped polysilicon and titanium nitride layers while minimizing the removal of silicon oxide and silicon nitride layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polishing compositions are used to achieve high removal rates for boron-doped polysilicon, then the removal rate increases, but the removal rate for silicon oxide and silicon nitride also increases, reducing selectivity
Solution Approach 1:
The invention changes the chemical parameters of the polishing composition by using titanium oxide abrasive with specific surface area (5-50 m²/g) and controlling pH (2-7), along with specific oxidizing agents, to achieve differential removal rates. This allows high removal rate for boron-doped polysilicon (500-2000 Å/min) while maintaining low removal rate for silicon oxide and silicon nitride (<50 Å/min), resolving the selectivity contradiction
Solution Approach 2:
The invention uses a composite polishing composition combining titanium oxide abrasive particles with specific surface area characteristics, oxidizing agents (such as hydrogen peroxide, ammonium persulfate, or oxone), and controlled pH buffers. This composite formulation creates synergistic effects that enhance removal of boron-doped polysilicon while protecting silicon oxide and silicon nitride layers, achieving both high productivity and manufacturing precision
2Productivity
If polishing composition is optimized for high removal rate of boron-doped polysilicon, then productivity improves, but damage to underlying layers increases
Solution Approach 1:
By precisely controlling the surface area of titanium oxide particles (5-50 m²/g) and pH (2-7), the invention optimizes the mechanical and chemical action of the polishing composition. This parameter control enables high removal rate for the target layer while minimizing damage to underlying stopping layers, achieving selective removal without excessive damage
3Productivity
If titanium oxide abrasive with high surface area is used to increase removal rate, then productivity increases, but composition complexity increases
Solution Approach 1:
The invention simplifies the composition by focusing on one key parameter - titanium oxide surface area (5-50 m²/g) - rather than using complex mixtures of multiple abrasives. This single-parameter optimization, combined with standard pH buffers and common oxidizing agents, achieves high removal rates while keeping the composition relatively simple and easy to manufacture
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 described polishing composition achieves high removal rates for boron-doped polysilicon and titanium nitride layers while maintaining low removal rates for silicon oxide and silicon nitride layers, thus providing the necessary selectivity for advanced memory device fabrication.
Implementation Method 1
The abrasive material may be incorporated into the polishing pad instead of, or in addition to, being suspended in the polishing composition
Implementation Method 2
contacting the surface with a polishing pad saturated with the polishing composition
Implementation Method 3
a titanium oxide abrasive; (b) an oxidizing agent
Data Source
AI summary
The invention provides a chemical-mechanical polishing composition comprising: (a) a titanium oxide abrasive; (b) an oxidizing agent; and (c) water, wherein the chemical-mechanical polishing composition has a pH of about 7 or less. The invention also provides a method of chemically-mechanically polishing a substrate, especially a substrate comprising a boron-doped polysilicon layer on a surface of the substrate, using said composition.