EUV Photoresist Underlayer Adhesion Modulation via Alkaline Treatment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In extreme ultraviolet (EUV) lithography, existing photoresist material systems face challenges with low efficiency due to limited adhesion strength between the photoresist and underlayer, leading to difficulties in fully removing exposed photoresist material, resulting in residual scum that causes patterning defects.
Innovation Solution
A modifiable underlayer structure is introduced, where a first underlayer is converted from hydrophobic to hydrophilic using an alkaline solution, reducing adhesion strength with the hydrophobic photoresist, allowing easier removal of scum, and a dual underlayer approach with a thin, porous second underlayer facilitates this conversion, ensuring high adhesion for patterning and low adhesion for scum removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional underlayer is used with photoresist, then adhesion strength is maintained at a moderate level, but the photoresist cannot be fully removed after exposure, leaving residual scum that causes patterning defects
Solution Approach 1:
The underlayer's adhesion properties are made dynamic by introducing a modifiable surface treatment layer that can change its adhesion strength state. The layer transitions from a high adhesion state during patterning to a low adhesion state during scum removal, enabling both strong bonding when needed and easy removal when needed.
Solution Approach 2:
The surface energy parameter of the underlayer is changed by applying a modifiable surface treatment layer with different surface energy characteristics. This parameter change allows the underlayer to exhibit different adhesion strengths under different process conditions, resolving the contradiction between maintaining adhesion during patterning and enabling scum removal.
2Reliability
If the underlayer adhesion strength is increased to prevent pattern collapse, then patterning reliability improves, but scum removal becomes difficult and residual scum increases
Solution Approach 1:
The underlayer is segmented into multiple functional layers: a base underlayer providing structural support and a modifiable surface treatment layer providing controllable adhesion. This segmentation allows each layer to perform its specific function independently, with the surface treatment layer being removable after use.
Solution Approach 2:
The modifiable surface treatment layer acts as an intermediary between the base underlayer and the photoresist. It provides the necessary adhesion during patterning but can be easily removed afterward, preventing residual scum formation while maintaining pattern stability.
3Strength
If a thick underlayer is used to ensure structural integrity, then mechanical strength improves, but adhesion modulation and scum removal efficiency deteriorate
Solution Approach 1:
The underlayer structure is segmented into a thick base layer for structural integrity and a thin modifiable surface treatment layer for adhesion control. This segmentation allows the thick base layer to provide mechanical strength while the thin surface layer enables easy scum removal through adhesion modulation.
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 approach enhances the efficiency of photoresist removal, reducing patterning defects and enabling high-quality pattern transfer by balancing adhesion strength for both patterning and scum removal processes.
Implementation Method 1
a first underlayer is converted from hydrophobic to hydrophilic using an alkaline solution, reducing adhesion strength with the hydrophobic photoresist
Implementation Method 2
a dual underlayer approach with a thin, porous second underlayer facilitates this conversion
Data Source
AI summary
Embodiments disclosed herein include a method of developing a patterning stack. In an embodiment, the method comprises providing a patterning stack, where the patterning stack comprises an underlayer and a photoresist over the underlayer, and where the underlayer has a first adhesion strength with the photoresist. The method may further comprise exposing and developing the photoresist with electromagnetic radiation and a developer, where scum remains on a surface of the underlayer. In an embodiment, the method further comprises treating the underlayer so that the underlayer has a second adhesion strength with the scum, and removing the scum.