Iodized Aromatic Resist for EUV Lithography Edge Roughness
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Solution Overview
Problem
Current EUV lithography technologies face challenges in achieving high resolution and reduced edge roughness and dimensional variation due to photon number variation, acid diffusion, and insufficient control of acid diffusion in chemically amplified resist materials.
Innovation Solution
A positive resist composition is developed, comprising a compound with a nitrobenzyl ester group bonded to an iodized aromatic ring, combined with a base polymer having carboxy or phenolic hydroxy groups, which minimizes acid diffusion and enhances photo-absorption, leading to improved sensitivity and dissolution contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If iodine atoms are introduced into EUV-reactive acid generators or photo-decomposable quenchers to increase photon absorption, then sensitivity is improved and edge roughness is reduced, but image blur due to acid diffusion cannot be avoided
Solution Approach 1:
The patent extracts the acid generator function from the iodine-containing compound and places it in a separate component. The iodine-containing compound serves only as the photo-absorptive resist material, while the acid generator is added as a distinct additive, thereby eliminating the conflict between photon absorption and acid diffusion control.
Solution Approach 2:
The patent creates a composite resist system combining iodine-containing aromatic compounds with acid generators. This composite approach allows the iodine compound to provide high photon absorption for reduced edge roughness, while the separate acid generator enables controlled acid diffusion, achieving both improved sensitivity and reduced image blur simultaneously.
2Measurement precision
If molecular resist materials with low molecular weight are used to reduce edge roughness, then dissolution uniformity is improved, but acid diffusion control becomes insufficient
Solution Approach 1:
The patent extracts the acid diffusion control function from the molecular resist structure and assigns it to a separate acid generator component. This allows the low molecular weight iodine-containing compound to provide excellent dissolution uniformity while the added acid generator supplies the necessary acid diffusion control capability.
Solution Approach 2:
The patent combines low molecular weight iodine-containing aromatic compounds with acid generators to create a composite resist system. This composite structure preserves the dissolution uniformity benefits of low molecular weight materials while adding the acid diffusion control functionality through the acid generator component.
3Measurement precision
If the resist film is rendered more photo-absorptive to reduce photon number variation, then sensitivity is improved, but dissolution contrast is reduced due to low alkaline solubility
Solution Approach 1:
The patent extracts the dissolution contrast function from the photo-absorptive iodine-containing compound and assigns it to a separate base polymer with high alkaline solubility. The iodine compound provides enhanced photon absorption for improved sensitivity, while the base polymer ensures high dissolution contrast through its alkaline solubility characteristics.
Solution Approach 2:
The patent creates a composite resist system combining iodine-containing aromatic compounds with highly alkaline-soluble base polymers. This composite structure allows the iodine compound to enhance photon absorption and sensitivity, while the base polymer provides high dissolution contrast, resolving the trade-off between sensitivity and dissolution contrast.
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 resist composition achieves high sensitivity, resolution, and reduced edge roughness and dimensional variation, making it suitable for forming fine patterns in microelectronic devices and photomasks.
Implementation Method 1
the nitrobenzyl group is decomposed to release chloric acid upon exposure to UV of wavelength 300 to 350 nm
Implementation Method 2
Upon exposure to UV of wavelength 300 to 350 nm, the nitrobenzyl group is decomposed to release chloric acid
Implementation Method 3
iodine atoms are highly absorptive, i.e., absorb more photons during EUV exposure
Data Source
AI summary
A positive resist composition comprising a compound having a nitrobenzyl ester group bonded to an iodized aromatic ring exhibits a higher sensitivity and resolution than the prior art and forms a pattern of good profile with low edge roughness or improved CDU after exposure and development.