Photoresist Composition for Negative Tone Development
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Solution Overview
Problem
Conventional photoresist compositions for negative tone development exhibit slow dissolution rates in developers, leading to poor pattern fidelity and resolution issues in semiconductor manufacturing, particularly for feature sizes below 40 nm.
Innovation Solution
The development of photoresist compositions comprising a matrix polymer with acid-labile groups, an additive polymer with low surface energy, and a photoacid generator, which undergoes a solubility switch upon exposure to actinic radiation and heat, allowing for improved dissolution rates and pattern formation in negative tone development processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photoresist compositions are used for negative tone development, then the process can be implemented with standard materials, but the dissolution rate in developers is slow leading to poor pattern fidelity
Solution Approach 1:
The patent modifies the chemical structure of the polymer by incorporating specific ester groups (isobornyl ester, adamantyl ester) and adjusting the molecular weight and composition ratios to optimize dissolution rate in organic developers while maintaining pattern fidelity for negative tone development
Solution Approach 2:
The photoresist composition uses a composite polymer structure combining multiple functional groups (acid-labile groups, ester groups, hydrocarbon backbones) in specific ratios to achieve both fast dissolution rate and high pattern fidelity, rather than relying on a single polymer type
2Manufacturing precision
If shorter wavelengths of light are used for exposure, then higher resolution can be achieved, but the process complexity and cost increase
Solution Approach 1:
The patent optimizes the photoresist composition parameters (polymer molecular weight, ester group composition, acid generator type) to achieve high resolution at 193 nm wavelength without requiring migration to shorter wavelengths, thereby avoiding increased process complexity
3Speed
If lower molecular weight polymers are used, then dissolution rate in NTD developers increases, but photospeed and CD uniformity deteriorate
Solution Approach 1:
The patent identifies an optimal molecular weight range and composition ratio for the polymer that balances dissolution rate and CD uniformity, using specific ester group compositions (isobornyl ester 20-40%, adamantyl ester 10-30%) to achieve both fast dissolution and uniform pattern dimensions
Solution Approach 2:
The patent creates a composite polymer system combining different functional groups in optimized ratios, where the synergistic interaction between acid-labile groups, ester groups, and hydrocarbon backbones achieves both high dissolution rate and uniform CD control
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 photoresist compositions enhance resolution, top loss, focus latitude, exposure latitude, and defectivity, enabling the formation of geometrically uniform resist patterns and reducing migration of photoresist materials, thus improving the fabrication of fine patterns in semiconductor devices.
Implementation Method 1
Exposure to actinic radiation causes the photoacid generator to form an acid which, during post-exposure baking, causes cleavage of the acid-labile groups in the resin
Implementation Method 2
This creates a difference in solubility characteristics between exposed and unexposed regions of the resist in an aqueous alkaline developer solution
Data Source
AI summary
Provided are photoresist compositions useful in forming photolithographic patterns. Also provided are substrates coated with the photoresist compositions and methods of forming photolithographic patterns. The compositions, methods and coated substrates find particular applicability in the manufacture of semiconductor devices.