Novolac Resist Overlayer Film for EUV Lithography
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Solution Overview
Problem
Current EUV lithography techniques face challenges in effectively blocking undesirable UV and DUV light, which affects the resolution and sensitivity of EUV resist patterns, especially at wavelengths below 300 nm, and existing solutions do not provide optimal compositions for resist overlayer films.
Innovation Solution
A resist overlayer film forming composition comprising a novolac-based polymer with a hydroxy group and specific solvent systems, such as alcoholic solvents or water, is used to selectively transmit EUV light while blocking UV and DUV light, allowing for development with an alkaline solution without intermixing with the EUV resist.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a polymer including beryllium, boron, carbon, silicon, zirconium, niobium, or molybdenum is used as an overlayer film for EUV resist, then protection from contaminants and blocking of undesired radiation (UV/DUV) is improved, but the complexity of film formation systems increases
Solution Approach 1:
The patent uses a disposable organic overlayer film composed of water-soluble polymers (polyhydroxystyrene, polyacrylamide, polyacrylic acid) that can be easily applied and removed. This replaces complex vacuum deposition or CVD systems with a simple spin-coating process using aqueous solutions, eliminating the need for expensive and complex film formation equipment while achieving the same OOB blocking function.
Solution Approach 2:
The patent changes the chemical composition parameters of the overlayer film from inorganic materials (beryllium, boron, silicon compounds) to organic water-soluble polymers. This parameter change enables the use of simple aqueous coating processes instead of complex vacuum or CVD systems, while maintaining effective UV and DUV light blocking capabilities through the aromatic ring structures in the polymer chains.
2Manufacturing precision
If a top coating comprising polyhydroxystyrene or acryl compound is applied to block OOB, then resolution enhancement is improved, but the optimal composition and processing conditions remain undetermined
Solution Approach 1:
The patent systematically optimizes composition parameters including polymer type (polyhydroxystyrene, polyacrylamide, polyacrylic acid), molecular weight (10,000-1,000,000), concentration (0.1-10 wt%), and solvent composition (water, alcohols). It also optimizes processing parameters such as coating thickness (1-100 nm) and drying conditions. These defined parameter ranges provide clear manufacturing guidelines that eliminate the uncertainty about optimal composition and processing conditions.
3Manufacturing precision
If novolac material with naphthalene ring is used as resist overlayer film, then EUV lithography performance is improved, but intermixing with EUV resist may occur reducing pattern fidelity
Solution Approach 1:
The patent employs a water-soluble overlayer film that acts as a temporary protective layer during EUV exposure. This disposable overlayer can be easily removed by water rinsing after exposure, preventing any intermixing issues with the underlying EUV resist. The water-soluble nature ensures clean separation and removal without affecting the resist pattern fidelity.
Solution Approach 2:
The patent introduces a water-soluble polymer overlayer as an intermediary between the EUV resist and the environment. This intermediary layer provides OOB blocking and protection during exposure, then can be cleanly removed by water rinsing, serving as a temporary mediator that protects the resist without causing intermixing issues.
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 composition improves the resolution of EUV resist patterns by absorbing undesirable light in the 220-260 nm range, enhancing the sensitivity and pattern shape, and allows for easy removal of the overlayer film during development, thereby improving the overall lithography process.
Implementation Method 1
The composition improves the resolution of EUV resist patterns by absorbing undesirable light in the 220-260 nm range
Data Source
AI summary
A resist overlayer film forming composition that is used for a lithography process for manufacturing semiconductor devices, and selectively transmits EUV only, in particular, by blocking exposure light undesirable for EUV exposure, such as UV and DUV, without intermixing with a resist, and that can be developed with a developing solution after exposure. A resist overlayer film forming composition including: a hydroxyl group-containing novolac-based polymer containing a structure of (Formula 1-1):(in (Formula 1-1), Ar1 is a divalent organic group that contains 1 to 3 benzene ring(s) and optionally contains a hydroxy group; Ar2 is a benzene ring group, a naphthalene ring group, or an anthracene ring group; each of the hydroxy group and R1 is a substituent for a hydrogen atom on a ring of Ar2); and a solvent.