Cationic Silica CMP Slurry for Low-Defect Spin-On Carbon Polishing
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Solution Overview
Problem
Current chemical mechanical polishing (CMP) methods for organic polymer films on semiconductor wafers suffer from high costs and defects due to high abrasive concentrations, and existing technologies do not effectively address the need for consistent and tunable polishing performance, especially at low silica solids contents.
Innovation Solution
A CMP method using an aqueous polishing composition with 0.05-7 wt% elongated, bent, or nodular silica particles containing cationic nitrogen atoms and 0.005-0.5 wt% sulfate group containing surfactants, applied at acidic pH below the isoelectric point of the silica particles, to achieve high removal rates and selectivity with minimal defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high concentrations of abrasive are used in CMP slurry, then removal rate is improved, but cost increases and defects (scratches) increase
Solution Approach 1:
The invention changes the chemical parameters of the slurry by using cationic silica particles with specific surface charge characteristics and controlling pH to be below the isoelectric point. This enables effective polishing at low abrasive concentrations (0.05-7 wt%) while maintaining high removal rates and reducing defects, resolving the contradiction between productivity and harmful effects
Solution Approach 2:
The invention creates a composite slurry system combining cationic silica particles with sulfate group containing surfactants. This composite approach enhances polishing efficiency at low abrasive loads through synergistic interactions between the charged particles and surfactant molecules, improving removal rate without increasing abrasive concentration or causing scratches
2Productivity
If oxidants are added to CMP slurry, then removal rate is improved, but cost increases
Solution Approach 1:
The invention replaces chemical oxidation mechanisms with mechanically-driven abrasion using cationic silica particles. The unique charge characteristics of these particles enable effective material removal through mechanical action alone, eliminating the need for oxidant chemicals and associated costs while maintaining high removal rates
3Object-generated harmful factors
If low silica solids content is used in CMP slurry, then cost and defects are reduced, but polishing consistency and tunability deteriorate
Solution Approach 1:
The invention introduces critical parameter changes by controlling pH below the isoelectric point of the cationic silica particles and using sulfate group containing surfactants. These parameter changes enable consistent and tunable polishing performance even at low silica solids contents (0.05-7 wt%), resolving the contradiction between reducing defects/cost and maintaining polishing reliability
Solution Approach 2:
The invention establishes feedback control through the interaction between cationic silica particles, sulfate surfactants, and pH control. This self-regulating system maintains consistent polishing performance at low abrasive concentrations by adjusting the chemical environment to optimize particle-substrate interactions, ensuring reliability without requiring high silica content
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 method enables consistent and tunable polishing of organic polymer films with high removal rates and selectivity, reducing defects and costs by using low abrasive contents and optimizing the interaction between cationic silica particles and sulfate surfactants.
Implementation Method 1
aqueous CMP polishing composition comprising from 0.05 to 7 wt. % of an abrasive of elongated, bent or nodular silica particles containing within at least one of the silica particles one or more cationic nitrogen or phosphorus atoms... from 0.005 to 0.5 wt. % of a sulfate group containing surfactant... having a pH ranging from 1.5 to 4.5, wherein the pH is below the isoelectric point (IEP) of the silica particles
Implementation Method 2
having a pH ranging from 1.5 to 4.5, wherein the pH is below the isoelectric point (IEP) of the silica particles
Data Source
AI summary
The present invention provides methods for chemical mechanical polishing (CMP polishing) spin coated organic polymer films on a semiconductor wafer or substrate as part of lithography or as part of electronic packaging. The methods comprising spin coating an organic polymer liquid on a semiconductor wafer or substrate; at least partially curing the spin coating to form an organic polymer film; and, CMP polishing the organic polymer film with a polishing pad and an aqueous CMP polishing composition having a pH ranging from 1.5 to 4.5 and comprising elongated, bent or nodular silica particles containing one or more cationic nitrogen or phosphorus atoms, from 0.005 to 0.5 wt. %, based on total CMP polishing composition solids, of a sulfate group containing C8 to C18 alkyl or alkenyl group surfactant, and a pH adjusting agent.