Positive Resist Composition for Photomask Size Controllability
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Solution Overview
Problem
The existing resist materials used in photomask production, particularly during direct drawing with electron beams in vacuum, suffer from poor size controllability, leading to inconsistencies in pattern size, which is critical for miniaturization beyond the 65 nm node in semiconductor and liquid crystal display manufacturing.
Innovation Solution
A positive resist composition comprising a resin component with alkali-soluble units and acid-dissociable dissolution inhibiting groups, combined with an acid generator, is developed. This composition includes specific units derived from α-methylhydroxystyrene and α-lower alkyl acrylate esters, along with aromatic amines, to enhance size controllability and stability in vacuum conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing resist materials are used in direct drawing with electron beams in vacuum, then the resist material can be applied for photomask production, but size controllability deteriorates leading to inconsistencies in pattern size
Solution Approach 1:
The patent modifies the chemical composition parameters of the resist material by incorporating specific units (a1) with alkali-soluble groups and units (a2) with acid-dissociable dissolution inhibiting groups. This parameter change in the resist composition enables precise control over pattern size during electron beam direct drawing while maintaining reliability through consistent dissolution behavior in alkaline developers.
Solution Approach 2:
The invention creates a composite resist material structure combining different functional units: alkali-soluble units (a1) that enable development, and acid-dissociable dissolution inhibiting units (a2) that prevent premature dissolution. This composite approach resolves the contradiction by integrating multiple functions into a single resist system that maintains both size controllability and pattern consistency.
2Manufacturing precision
If the wavelength of exposure light source is shortened to miniaturize pattern size, then resolution improves, but manufacturing complexity increases with introduction of new excimer lasers and exposure systems
Solution Approach 1:
The patent changes the chemical parameters of the resist material to be compatible with existing KrF and ArF excimer laser wavelengths. By adjusting the resist composition to include specific acid-dissociable groups and alkali-soluble units, the system achieves fine pattern resolution without requiring transitions to more complex shorter-wavelength systems like F2 excimer or EUV.
3Manufacturing precision
If conventional resist compositions are used for photomask production, then the process can be maintained, but stability in vacuum conditions deteriorates affecting pattern formation accuracy
Solution Approach 1:
The invention modifies the compositional parameters of the resist by incorporating units with specific chemical groups that exhibit enhanced stability in vacuum environments. The acid-dissociable dissolution inhibiting groups and alkali-soluble units are selected to maintain structural integrity and prevent degradation under vacuum conditions, thereby preserving pattern formation accuracy.
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 proposed resist composition achieves excellent size controllability and stability in vacuum, enabling precise pattern formation even on chromium oxide layers, thus facilitating the production of high-resolution photomasks with consistent pattern sizes, essential for advanced semiconductor and display technologies.
Implementation Method 1
a chemically amplified resist composition containing a base resin and an acid generator which generates an acid upon exposure is used
Implementation Method 2
the positive resist composition further comprising an aromatic amine (C)
Data Source
AI summary
A positive resist composition having excellent size controllability, and a resist pattern forming method are provided. This positive resist composition contains a resin component (A) comprising an alkali soluble constituent unit (a1) which comprises a constituent unit (a11) derived from (α-methyl)hydroxystyrene, and a constituent unit (a2) which has an acid dissociable dissolution inhibiting group including an acid dissociable dissolution inhibiting group (II) represented by the following general formula (II) and/or a specific chain acid dissociable dissolution inhibiting group (III); an acid generator component (B) which generates an acid upon exposure; and preferably contains an aromatic amine (C).