Tunable Polishing Layer for Semiconductor CMP Selectivity
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Solution Overview
Problem
Current chemical mechanical polishing consumables lack the necessary range of removal rate selectivities between silicon oxide and silicon nitride materials, limiting the flexibility of semiconductor device designs as semiconductor substrates become increasingly complex.
Innovation Solution
A chemical mechanical polishing method using a polishing pad with a composition derived from a polyfunctional isocyanate and an amine initiated polyol curative, where the stoichiometric ratio of reactive hydrogen groups to unreacted isocyanate groups is tuned between 1.25 to 1.8 to achieve fine-tunable removal rate selectivity between silicon oxide and silicon nitride materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional polishing consumables with fixed composition are used, then the polishing process is simple to operate, but the removal rate selectivity between silicon oxide and silicon nitride is limited and cannot be tuned
Solution Approach 1:
The patent applies parameter changes by systematically varying the stoichiometric ratio of reactive hydrogen groups to unreacted isocyanate groups in the polishing layer composition. By adjusting this chemical parameter within specific ranges (e.g., 0.8-1.2), the removal rate selectivity between silicon oxide and silicon nitride can be precisely tuned to match different device design requirements, transforming a fixed-property consumable into a tunable system.
Solution Approach 2:
The patent employs composite materials by combining polyfunctional isocyanate with amine-initiated polyol curative to create a polishing layer with tailored properties. This composite approach allows the material to exhibit both mechanical polishing capabilities and chemical reactivity toward specific substrates, enabling enhanced removal rate selectivity that cannot be achieved with single-material systems.
2Adaptability or versatility
If the stoichiometric ratio of amine initiated polyol curative to polyfunctional isocyanate is adjusted to tune removal rate selectivity, then the adaptability to different device designs is improved, but the complexity of polishing layer formulation increases
Solution Approach 1:
The patent systematically varies the stoichiometric ratio parameter within defined ranges to achieve desired removal rate selectivity values. This parameter-based formulation approach provides a predictable relationship between composition and performance, making the manufacturing process more controllable despite the increased formulation complexity.
Solution Approach 2:
The patent introduces dynamics into the polishing layer formulation by enabling continuous adjustment of the stoichiometric ratio based on specific application requirements. This dynamic formulation strategy allows the same base materials to be adapted for different device designs by simply modifying the mixing ratio, rather than requiring entirely different material systems.
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 provides enhanced removal rate selectivity performance, enabling the manufacture of more complex semiconductor substrates by precisely controlling the polishing process, thereby improving the planarization and surface quality of semiconductor wafers.
Implementation Method 1
a polishing layer having a composition that is a reaction product of ingredients, comprising: a polyfunctional isocyanate and an amine initiated polyol curative
Implementation Method 2
the polishing pad and wafer typically rotate relative to one another. As the polishing pad rotates beneath the wafer, the wafer sweeps out a typically annular polishing track, or polishing region, wherein the wafer's surface directly confronts the polishing layer
Implementation Method 3
the wafer surface is polished and made planar by chemical and mechanical action of the polishing layer and polishing medium on the surface
Data Source
AI summary
A chemical mechanical polishing method is provided comprising: providing a substrate, wherein the substrate comprises a silicon oxide and a silicon nitride; providing a polishing slurry; providing polishing pad, comprising: a polishing layer having a composition that is a reaction product of ingredients, comprising: a polyfunctional isocyanate and an amine initiated polyol curative; wherein the stoichiometric ratio of the amine initiated polyol curative to the polyfunctional isocyanate is selected to tune the removal rate selectivity of the polishing layer; creating dynamic contact between the polishing surface and the substrate; dispensing the polishing slurry on the polishing pad at or near the interface between the polishing surface and the substrate; and, removing at least some of the silicon oxide and the silicon nitride from the substrate.