Silica CMP Slurry Chemistry for Oxide-to-Silicon Selectivity
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Solution Overview
Problem
Current chemical mechanical polishing compositions face challenges in achieving sufficient polishing selectivity of oxides to silicon-containing materials, such as silicon-germanium or silicon, which limits their use as polishing stop layers, resulting in increased process complexity and production time.
Innovation Solution
A polishing composition containing silica particles with a controlled silanol group density and an additive molecule with a specific structure, used in a specific pH range, enhances the polishing selectivity of oxides to silicon-containing materials, allowing for the use of silicon-containing materials as polishing stop layers without the need for additional stop layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional polishing compositions are used, then the polishing process can be performed, but the polishing selectivity of oxides to silicon-containing materials is insufficient
Solution Approach 1:
The patent applies parameter changes by controlling the silanol group density of silica particles to a specific range (0.01 to 0.5 μmol/m²) and adjusting the pH of the polishing composition to 2.0 or lower. These parameter modifications enable silicon-containing materials to function as effective polishing stop layers, achieving sufficient polishing selectivity without adding extra process steps.
Solution Approach 2:
The patent uses composite material principles by creating a polishing composition that combines silica particles with specific silanol group densities, oxidizing agents, and surfactants in a controlled pH environment. This composite formulation achieves high polishing selectivity between oxides and silicon-containing materials, eliminating the need for separate polishing stop layers.
2Device complexity
If polishing selectivity is increased to allow silicon-containing materials as stop layers, then process complexity is reduced, but existing polishing compositions cannot achieve sufficient selectivity
Solution Approach 1:
The patent achieves the desired polishing selectivity by changing key parameters: controlling silanol group density to 0.01-0.5 μmol/m² and maintaining pH at 2.0 or lower. These parameter changes enable silicon-containing materials to serve as effective polishing stop layers, simplifying the process while achieving the required selectivity.
3Productivity
If the polishing speed of oxides is increased to shorten processing time, then productivity improves, but polishing selectivity may be compromised
Solution Approach 1:
The patent simultaneously optimizes both polishing speed and selectivity through parameter changes. By controlling silanol group density and maintaining low pH (2.0 or lower), the composition achieves high oxide removal rates while preserving excellent polishing selectivity, allowing silicon-containing materials to function as reliable stop layers.
Solution Approach 2:
The patent introduces an intermediary role for the controlled silanol groups on silica particle surfaces. These silanol groups act as mediators that enhance the chemical interaction with oxides for high removal rates while the low pH environment and specific silanol density prevent excessive interaction with silicon-containing materials, maintaining selectivity.
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 significantly increases the polishing selectivity and removal rate of oxides, simplifying the process, reducing production time and cost, and improving surface flatness by enabling the use of silicon-containing materials as effective polishing stop layers.
Implementation Method 1
a silanol group density on a surface of the silica particles is 0 to 3.0 groups/nm2
Implementation Method 2
The chemical mechanical polishing technique includes a method in which the surface of an object to be polished (workpiece) such as a semiconductor substrate is flattened using a polishing composition containing abrasive grains such as silica, alumina, or ceria, an anticorrosive, a surfactant and the like
Data Source
AI summary
Provided are a polishing composition, a polishing method, and a method for manufacturing a substrate.The polishing composition contains polishing abrasive grains, an additive molecule, a pH adjusting agent, and a dispersing medium. The polishing abrasive grains contain silica particles, and the silanol group density on the surface of the silica particles is 0 to 3.0 groups/nm2. The silanol group density is calculated and determined based on the specific surface area measured by the BET method and the amount of silanol groups measured by titration. The pH adjusting agent is used to adjust the pH of the polishing composition to a range of 1.5 or more and 4.5 or less. The additive molecule has a structure represented by Formula (I).(In Formula (I), R1, R2, n, m, p, q, and r are as defined in the specification.)