Self-priming resist for EUV hardmask adhesion
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Solution Overview
Problem
In extreme ultraviolet (EUV) lithography, the limited resist height/etch budget leads to pattern collapse, and existing hardmask materials struggle with adhesion to EUV resist, especially when the silicon antireflective coating thickness goes below 10 nm, requiring additional adhesion layers that can complicate the process.
Innovation Solution
A self-priming resist is developed, comprising a random copolymer and a polymer brush with a cleavable unit and grafting group, which can graft to the hardmask at low temperatures and be cleaved during development, allowing for a single-step adhesion layer and resist formation without additional processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional adhesion layers such as BARC or polymer brush are used, then adhesion between resist and hardmask is improved, but process complexity and number of steps increase
Solution Approach 1:
The patent combines the adhesion layer and resist into a single integrated composition. The polymer brush is incorporated directly into the resist formulation, creating a unified material that provides both adhesion to the hardmask and resist functionality, eliminating the need for separate adhesion layer deposition steps
Solution Approach 2:
The integrated resist composition performs multiple functions simultaneously: it provides adhesion to the hardmask through the polymer brush component, forms the resist pattern through the photoactive components, and enables subsequent etching. This multi-functional material replaces what traditionally required separate specialized layers
2Reliability
If additional adhesion layers are deposited, then adhesion is improved, but material and solvent usage increase
Solution Approach 1:
By merging the adhesion layer and resist into a single composition, the patent eliminates the need for separate materials and solvents for each layer. The unified formulation reduces total material consumption and simplifies solvent management in the process
3Manufacturing precision
If resist height is increased to maintain etch budget, then pattern collapse is avoided, but manufacturing precision deteriorates due to line edge roughness
Solution Approach 1:
The patent employs a sacrificial polymer brush component that is intentionally designed to be removed during development. This disposable element provides temporary support during coating and baking, then is selectively removed to create clean patterns without compromising final pattern fidelity
Solution Approach 2:
The polymer brush acts as an intermediary between the hardmask and the photoresist matrix. It provides a transition layer that improves interfacial adhesion and reduces stress, preventing pattern collapse during the etching process while maintaining pattern definition
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 adhesion between the resist and hardmask, reduces material and solvent usage, and improves pattern transfer with high throughput, minimizing line edge roughness and pattern collapse while maintaining lithography performance.
Implementation Method 1
The grafting group is selected to graft to a hardmask material at a temperature near or below the typical post-apply bake temperature of the resist
Implementation Method 2
the cleavable group is cleavable from the second random copolymer by one of a photoacid, a base, and a photon
Data Source
AI summary
A self-priming resist may be formed from a first random copolymer forming a resist and a polymer brush having the general formula poly(A-r-B)-C-D, wherein A is a first polymer unit, B is a second polymer unit, wherein A and B are the same or different polymer units, C is a cleavable unit, D is a grafting group and r indicates that poly(A-r-B) is a second random copolymer formed from the first and second polymer units. The first random copolymer may be the same or different from the second random polymer. The self-priming resist can create a one-step method for forming an adhesion layer and resist by using the resist/brush blend.