Polysilicon CMP Slurry pH Control and Abrasive Synergy
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Solution Overview
Problem
The chemical mechanical polishing industry faces a challenge in achieving high polysilicon removal rates from substrates using acidic oxide slurries, which are typically limited to low removal rates, especially for thick polysilicon applications.
Innovation Solution
A method involving the mixing of an acid chemical mechanical polishing slurry containing water, abrasive particles, and an organic acid with an alkaline solution containing a low alkyl chain amine compound, applied to a polishing pad to create dynamic contact and enhance polysilicon removal, while maintaining a pH greater than 7 to prevent agglomeration of abrasive particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If acidic oxide slurries are used for polysilicon chemical mechanical polishing, then planarization efficiency and defectivity are improved, but polysilicon removal rate deteriorates
Solution Approach 1:
The patent changes the pH parameter of the polishing slurry from acidic (conventional) to alkaline (pH > 7). This fundamental parameter change enables the slurry to achieve both high planarization efficiency and high polysilicon removal rate, resolving the technical contradiction between manufacturing precision and productivity
Solution Approach 2:
The patent uses a composite abrasive system containing both colloidal silica particles and ceria particles. This composite material composition synergistically provides excellent planarization efficiency while maintaining high removal rates for thick polysilicon layers, addressing the contradiction between precision and productivity
2Manufacturing precision
If acidic oxide slurries with low silica weight percent are used, then planarization efficiency is improved, but polysilicon removal rate deteriorates
Solution Approach 1:
The patent fundamentally changes the pH parameter from acidic to alkaline (pH > 7), which transforms the chemical behavior of the slurry components. This enables effective polysilicon removal even at low silica concentrations (0.5-2 wt%), simultaneously achieving high planarization efficiency and high removal rate
Solution Approach 2:
The composite abrasive system of colloidal silica and ceria particles works synergistically in alkaline environment to provide both superior planarization and high removal rate, resolving the contradiction between precision and productivity
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
This method significantly enhances polysilicon removal rates, reduces static etch rates, and provides smooth polished surfaces, effectively addressing the limitations of conventional acidic oxide slurries.
Implementation Method 1
maintaining a pH greater than 7 to prevent agglomeration of abrasive particles
Implementation Method 2
a polishing composition ('slurry') or other polishing solution is provided between the wafer and the polishing pad. Thus, the wafer surface is polished and made planar by the chemical and mechanical action of the pad surface and slurry
Implementation Method 3
an acid chemical mechanical polishing slurry containing water, an organic acid and abrasive particles
Data Source
AI summary
A method of enhancing the removal rate of polysilicon from a substrate includes mixing an acid chemical mechanical polishing slurry containing water, an organic acid and an abrasive with an alkaline solution containing water, an abrasive, a low alkyl amine compound; providing a chemical mechanical polishing pad, having a polishing surface; creating dynamic contact at an interface between the polishing pad and the substrate; and dispensing the mixture of the chemical mechanical polishing slurry and the alkaline solution onto the polishing surface at or near the interface between the polishing pad and the substrate, wherein some of the polysilicon is polished away from the substrate.