Spin-on Carbon Planarizing Composition for High Aspect Ratio Vias
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Solution Overview
Problem
Current photolithography processes face challenges in achieving uniform planarization over structures with high aspect ratios or large trenches/vias, leading to high bias between open and dense areas, which requires additional processing steps and can result in photoresist poisoning and compatibility issues due to the use of existing planarizing materials.
Innovation Solution
A method involving the application of a planarizing composition with protected hydroxy groups that undergo deprotection and crosslinking upon heating, forming a final planarizing layer with reduced bias and improved flow characteristics to uniformly fill openings, thereby eliminating the need for extra processing steps and enhancing compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a large thickness of planarizing material is deposited to achieve planarization, then the planar top surface is improved, but the overburden for further processing steps increases
Solution Approach 1:
The patent changes the physical and chemical parameters of the planarizing composition, specifically using a low viscosity composition (5-20 cP) that enables superior flow characteristics. This parameter change allows the material to self-level and fill vias/trenches effectively with a thinner deposit (50-200 nm), reducing overburden while maintaining planarization quality
Solution Approach 2:
The patent employs a composite material system consisting of a polymer matrix with specific functional groups (carboxylic acid, hydroxyl, or amine) combined with controlled viscosity additives and crosslinking agents. This composite structure enables both the flow characteristics needed for via filling and the adhesion properties required for planarization, eliminating the need for thick deposits
2Manufacturing precision
If multiple processing steps (reflow baking, CMP, chemical develop-back, plasma etch back) are used to achieve planarization, then the planarization quality is improved, but the process complexity and time increase
Solution Approach 1:
The patent merges multiple functions into a single planarizing composition: adhesion promotion, via/trench filling, planarization, and crosslinking stability. This consolidation eliminates the need for separate reflow baking, CMP, or plasma etch back steps, reducing process complexity from multiple steps to a single spin-coat and bake process
Solution Approach 2:
The planarizing composition is designed with universal functionality to perform multiple roles: it adheres to underlying structures, flows into high aspect ratio vias/trenches, provides a planar surface, and resists photoresist poisoning. This multi-functionality in a single material system eliminates the need for multiple specialized processing steps
3Manufacturing precision
If photoresist materials with weakly basic functional groups are used for planarization, then the planarization function is achieved, but photoresist poisoning and footing or scumming occur
Solution Approach 1:
The patent changes the chemical parameter of the planarizing composition by using polymers with specific functional groups (carboxylic acid, hydroxyl, or amine) that have appropriate pKa values. These functional groups provide the necessary adhesion and flow characteristics without the photoresist poisoning effects associated with weakly basic groups, as they do not interfere with photoresist chemistry
4Manufacturing precision
If planarizing materials with functional groups that react with acid groups are used, then the planarization is achieved, but gelation or precipitation occurs which clogs the spin bowl's piping system
Solution Approach 1:
The patent changes the chemical stability parameter by selecting functional groups (carboxylic acid, hydroxyl, amine) that are chemically stable and do not undergo gelation or precipitation reactions with acid groups in the spin bowl system. These functional groups maintain solubility and stability throughout the coating process, preventing piping clogs while providing necessary adhesion and planarization functions
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 solution achieves a planarizing layer with a bias of less than 30 nm, allowing for complete filling of openings and reducing the need for additional processing steps, such as CMP or develop-back, while preventing photoresist poisoning and improving spin-bowl compatibility.
Implementation Method 1
The layer is heated, during which the protective groups begin to be removed from the compound
Implementation Method 2
the compound crosslinks to form a final planarizing layer
Data Source
AI summary
Planarizing and spin-on-carbon (SOC) compositions that fill vias and/or trenches on a substrate while planarizing the surface in a single thin layer coating process are provided. The compositions can planarize wide ranges of substrates with vias or trenches of from about 20 nm to about 220 nm wide, and up to about 700 nm deep. These extraordinary properties come from the low molecular weight of the polymers used in the materials, thermally-labile protecting groups on the polymers, and a delayed crosslinking reaction.