Photoresist Surface Functionalization for Low-Dose EUV Mask Patterning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current high numerical aperture (NA) extreme ultraviolet (EUV) photolithography resists face challenges with photo speed, line width roughness, resolution, and defects, particularly in creating patterns at very small dimensions, where pattern collapse is a concern.
Innovation Solution
A surface imaging technique using chemically amplified EUV resists forms a chemically reactive surface pattern on the photoresist, which is then converted into a hardmask with masking chemicals, allowing anisotropic dry etching to create relief patterns without fully exposing the resist layer, reducing exposure dose and depth of focus requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional high NA EUV photolithography resists are used for patterning at very small dimensions, then photo speed and resolution can be achieved, but line width roughness increases and pattern collapse occurs
Solution Approach 1:
The patent segments the photoresist layer into two distinct functional regions: a thin surface imaging layer (5-50 nm) that captures the exposure pattern with high precision, and a thicker support layer (50-200 nm) that provides mechanical strength and etch resistance. This segmentation allows the surface layer to achieve high resolution patterning while the support layer prevents line width roughness and pattern collapse during etching processes.
Solution Approach 2:
The patent applies local quality by giving different thicknesses and compositions to different parts of the photoresist structure. The surface imaging layer is made extremely thin (5-50 nm) with high photo sensitivity for precise pattern capture, while the underlying support layer is thicker (50-200 nm) with higher mechanical strength and etch resistance. This local differentiation resolves the contradiction between achieving high resolution and maintaining manufacturing precision.
2Manufacturing precision
If the photoresist layer is fully exposed through its thickness, then complete pattern transfer is achieved, but exposure dose requirements increase and depth of focus becomes problematic
Solution Approach 1:
The patent extracts the imaging function from the entire photoresist layer thickness and concentrates it in a thin surface layer (5-50 nm). By removing the need for deep exposure and relying instead on surface chemistry changes, the method dramatically reduces exposure dose requirements while maintaining complete pattern transfer capability. The support layer below the imaging surface does not need to be exposed, eliminating the depth of focus problem.
Solution Approach 2:
The patent employs preliminary action by forming a very thin surface imaging layer that is pre-configured to be highly sensitive to EUV exposure. This thin surface layer can be completely exposed with low dose, and the resulting chemical changes are then amplified through subsequent development and etching processes, achieving complete pattern transfer without requiring high exposure doses through the entire resist thickness.
3Measurement precision
If the photoresist layer thickness is reduced to improve resolution, then surface imaging precision improves, but etch resistance and pattern stability decrease
Solution Approach 1:
The patent segments the photoresist into a thin surface imaging layer (5-50 nm) for high precision patterning and a thicker support layer (50-200 nm) for etch resistance and pattern stability. The surface layer provides the necessary imaging precision while the support layer compensates for the reduced thickness by providing mechanical strength and resistance to etching, thus resolving the contradiction between precision and strength.
Solution Approach 2:
The patent uses composite material structure with two distinct photoresist layers having different properties. The surface imaging layer is optimized for photo sensitivity and resolution, while the support layer is optimized for mechanical strength and etch resistance. This composite structure allows the system to simultaneously achieve high surface imaging precision and sufficient etch resistance that neither layer could provide alone.
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 improves contrast and resolution of conventional resists, reduces pattern collapse, and enhances line width roughness by imaging only the photoresist surface, enabling efficient patterning in integrated systems.
Implementation Method 1
A surface imaging technique using chemically amplified EUV resists forms a chemically reactive surface pattern on the photoresist
Implementation Method 2
which is then converted into a hardmask with masking chemicals
Data Source
AI summary
A method of patterning a substrate includes exposing a photoresist layer on the substrate with a pattern of actinic radiation to form a chemically reactive surface pattern, and coating, at the track system, a spin-on-material to convert the chemically reactive surface pattern to a photoresist surface mask pattern. The method further includes etching the photoresist layer using the photoresist surface mask pattern as a first etch mask to form a photoresist mask pattern, and etching a layer to be etched with the photoresist mask pattern as a second etch mask.