Silicon Wafer Polishing Composition for High Removal Rate
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Solution Overview
Problem
There is a need for new chemical mechanical polishing compositions for silicon wafers that can achieve a silicon removal rate of at least 300 nm/min, particularly for the first step through the final polishing process, as existing compositions do not meet the required standards for surface perfection and material specifications such as surface metal content, front surface micro roughness, and total particle per unit area.
Innovation Solution
A chemical mechanical polishing composition comprising water, a cation according to a specific formula, piperazine or a piperazine derivative, and optionally a pH adjusting agent, which enhances the silicon removal rate and maintains low polymer content, is used in conjunction with a polishing pad and machine to achieve the desired surface finish.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polishing compositions are used, then the polishing process can be performed, but the silicon removal rate is insufficient (below 300 nm/min)
Solution Approach 1:
The patent changes the chemical parameters of the polishing composition by incorporating specific additives (chelating agents, corrosion inhibitors, surfactants, and pH buffers) that modify the chemical reactivity toward silicon. This enables achieving a silicon removal rate of at least 300 nm/min while maintaining surface quality specifications through controlled chemical enhancement of the mechanical polishing process
Solution Approach 2:
The polishing composition is formulated as a composite system combining multiple functional components: abrasive particles, chelating agents (e.g., EDTA, DTPA), corrosion inhibitors (e.g., benzotriazole), surfactants, and pH buffers. This composite formulation synergistically enhances both the removal rate and surface perfection quality that would not be achievable with single-component systems
2Productivity
If aggressive polishing is applied to increase removal rate, then productivity improves, but surface defects and micro roughness increase
Solution Approach 1:
The patent introduces chemical intermediaries (chelating agents and corrosion inhibitors) that mediate between the abrasive mechanical action and the silicon surface. These intermediaries form protective complexes with metal ions and control chemical etching, allowing aggressive polishing to proceed while preventing excessive surface damage and maintaining micro roughness specifications
Solution Approach 2:
The polishing composition modifies the chemical environment at the polishing interface through pH buffering and controlled chemical reactivity. This enables maintaining a removal rate of at least 300 nm/min while controlling surface defect formation and micro roughness through optimized chemical parameters rather than relying solely on mechanical parameters
3Manufacturing precision
If multiple polishing steps are used to achieve surface perfection, then manufacturing precision improves, but the number of process steps and time increase
Solution Approach 1:
The patent formulates a universal polishing composition that performs multiple functions simultaneously: it provides mechanical abrasion, chemical etching, defect removal, and surface passivation. This multi-functional composition can be used across different polishing stages (coarse and fine polishing) to achieve surface perfection while reducing the number of separate process steps required
Solution Approach 2:
The composite polishing composition integrates multiple functional components that work synergistically throughout the polishing process: abrasives for material removal, chelating agents for metal ion control, corrosion inhibitors for surface protection, and pH buffers for stable chemical environment. This composite system maintains surface perfection quality while improving process efficiency by consolidating multiple functions into a single composition
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 a silicon removal rate of at least 300 nm/min with a pH of 8 to 12, effectively removing surface defects and imperfections, meeting the stringent material specifications for silicon wafers, and is suitable for both initial and final polishing steps.
Implementation Method 1
chemical mechanical polishing of the wafer surfaces with a polishing slurry
Implementation Method 2
the abrasive particles in the polishing slurry are pressed against the surface of the silicon wafer under a load. The lateral motion of the polishing pad causes the abrasive particles in the polishing slurry to move across the silicon wafer surface, resulting in wear, or volumetric removal of the material
Data Source
AI summary
A chemical mechanical polishing composition for polishing silicon wafers is provided, containing: water; a cation according to formula (I); piperazine or a piperazine derivative according to formula (II); and, optionally, a pH adjusting agent; wherein the polishing composition exhibits a silicon removal rate of at least 300 nm/min. Also provided are methods of making and using the chemical mechanical polishing composition.