Double Exposure Patterning for Sub-45nm Resolution
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Solution Overview
Problem
Current microfabrication techniques face challenges in achieving line widths of less than 45 nm using near ultraviolet rays, requiring shorter wavelengths or higher numerical apertures, which are costly and compromise depth of focus.
Innovation Solution
A method involving a double exposure patterning technique using a positive-working radiation-sensitive resin composition with a crosslinking agent, acid-unstable group, and radiation-sensitive acid generator, where a first resist layer is formed and made inactive, followed by a second resist layer formation in the space area of the first pattern, maintaining the first layer's insolubility in alkali.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If shorter wavelength radiation or higher numerical aperture lens is used to achieve line width of less than 45 nm, then manufacturing precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies segmentation by dividing the patterning process into multiple exposure steps. First, a mandrel pattern is formed, then a spacer layer is deposited and patterned, followed by removal of the mandrel. This multi-step approach enables sub-45nm line width achievement using existing 193nm lithography tools without requiring expensive shorter-wavelength equipment.
Solution Approach 2:
The patent employs preliminary action by pre-forming the mandrel pattern and spacer layer before final pattern transfer. The spacer layer is deposited and patterned in advance, creating a template that guides the final resist patterning. This preliminary structuring enables precise sub-45nm feature formation using conventional lithography.
2Manufacturing precision
If numerical aperture of lens is increased to improve resolution, then manufacturing precision is improved, but depth of focus decreases
Solution Approach 1:
The patent transitions from two-dimensional planar patterning to three-dimensional spacer-based patterning. By depositing vertical spacer layers on mandrel structures and using aerial image interference, the method achieves sub-45nm resolution while maintaining adequate depth of focus, as the spacer height provides an additional dimensional degree of freedom.
Solution Approach 2:
The spacer layer acts as an intermediary between the mandrel pattern and the final resist pattern. The spacer translates the mandrel dimensions into the desired final pattern dimensions through controlled deposition and etching processes, enabling resolution improvement without increasing numerical aperture.
3Manufacturing precision
If double exposure patterning is used to form high-resolution patterns, then manufacturing precision is improved, but production time increases
Solution Approach 1:
The patent merges multiple patterning operations into a unified spacer-based process flow. The mandrel formation, spacer deposition, and pattern transfer steps are integrated into a single manufacturing sequence, reducing the total number of separate exposure and development cycles compared to traditional double patterning methods.
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
Enables the formation of high-resolution patterns with improved focal depth without increasing costs, suitable for micronized semiconductor devices.
Implementation Method 1
a chemically amplified resist utilizing the chemical amplification effect of a component having an acid-dissociable functional group and a component (hereinafter referred to as 'an acid generator') which generates an acid upon irradiation (hereinafter referred to as 'exposure')
Implementation Method 2
a layer of a liquid high refractive index medium (liquid for liquid immersion lithography) such as pure water or a fluorine-containing inert liquid is caused to be present during exposure between the lens and the resist film on a substrate
Data Source
AI summary
A method for forming a pattern includes providing a first positive-working radiation-sensitive resin composition on a substrate to form a first resist layer. The first positive-working radiation-sensitive resin composition includes a crosslinking agent, a polymer containing an acid-unstable group and not containing a crosslinking group, a radiation-sensitive acid generator, and a solvent. The first resist layer is exposed selectively to radiation, and developed to form a first resist pattern. The first resist pattern is made inactive to radiation, or insolubilized in an alkaline developer or in a second positive-working radiation-sensitive resin composition. The second positive-working radiation-sensitive resin composition is provided on the substrate to form a second resist layer. The second resist layer is exposed selectively to radiation, and developed to form a second resist pattern in the space area of the first resist pattern.