Metal Photoresist Underlayer Deposition for Uniform Sub-10 Nm EUV Films
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Solution Overview
Problem
Current methods for forming photoresist underlayers, particularly for extreme ultraviolet (EUV) lithography, face challenges such as difficulty in achieving thicknesses less than 10 nm, high non-uniformity, poor adhesion, and induced porosity in underlying layers, which affect pattern resolution and stability.
Innovation Solution
The use of a cyclical process like atomic layer deposition to form a photoresist underlayer with precise thickness control, incorporating metal oxides, nitrides, or oxynitrides, and adjusting precursors and deposition conditions to achieve desired surface energy properties for improved adhesion and etch selectivity, along with the incorporation of carbon to enhance the underlayer's properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If spin-on glass (SOG) is deposited to achieve thickness less than 10 nm, then the underlayer thickness is reduced to improve pitch resolution and aspect ratios, but the within-substrate and substrate-to-substrate thickness non-uniformity becomes undesirably high
Solution Approach 1:
The patent changes the deposition parameters by using atomic layer deposition (ALD) instead of spin-coating, enabling precise control of film thickness at the nanometer scale. ALD processes allow for atomic-layer precision in thickness control, achieving uniform thin films below 10 nm that are impossible to obtain through conventional spin-on methods
Solution Approach 2:
The patent replaces the mechanical spin-coating process with a chemical vapor deposition process (ALD). This substitution eliminates the hydrodynamic limitations of spin-coating and enables precise thickness control through controlled chemical reactions, achieving uniform sub-10 nm films with minimal variation across the substrate
2Manufacturing precision
If the photoresist underlayer thickness is reduced to improve pattern resolution, then pitch resolution and aspect ratios are improved, but it becomes difficult to deposit SOG at the required thin thickness
Solution Approach 1:
The patent replaces spin-coating with atomic layer deposition, a process specifically suited for forming ultra-thin films. ALD enables precise deposition of sub-10 nm layers through controlled sequential reactions, making it easy to manufacture the required thin underlayers that are difficult to achieve with conventional methods
Solution Approach 2:
The patent changes the deposition method parameters by using ALD cycles with controlled precursor exposure and purge steps. This allows precise control over film thickness and composition, enabling easy formation of thin uniform underlayers with exact thickness control that is not achievable through spin-coating
3Reliability
If conventional photoresist underlayers are used, then the underlayer provides basic support, but the adhesion to EUV resist is poor and etch selectivity is insufficient
Solution Approach 1:
The patent uses composite material structures formed through ALD, creating underlayers with tailored compositions that combine multiple functional properties. The ALD process enables formation of composite oxide or nitride layers that simultaneously provide excellent adhesion to EUV resist and high selectivity to etch chemistries, achieving both requirements that conventional single-material underlayers cannot satisfy
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 approach enables the formation of thin, uniform photoresist underlayers with improved adhesion, etch selectivity, and pattern quality, reducing line edge roughness and line width roughness, while maintaining compatibility with EUV lithography processes.
Implementation Method 1
forming a photoresist underlayer overlying a surface of the substrate, wherein the photoresist underlayer comprises a metal... The photoresist underlayer can be formed using one or more of plasma-enhanced cyclic (e.g., atomic layer) deposition process and thermal cyclic deposition process
Implementation Method 2
forming a photoresist underlayer overlying a surface of the substrate... The photoresist underlayer can be formed using one or more of plasma-enhanced cyclic (e.g., atomic layer) deposition process
Data Source
AI summary
Methods of forming structures including a photoresist underlayer and structures including the photoresist underlayer are disclosed. Exemplary methods include forming the photoresist underlayer that includes metal. Techniques for treating a surface of the photoresist underlayer and/or depositing an additional layer overlying the photoresist underlayer are also disclosed.