Immersion Field-Guided Post-Exposure Bake for Smoother Resist Edges
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Solution Overview
Problem
Current photolithography processes face challenges with low throughput, increased line edge roughness, and decreased resist sensitivity due to the difficulty in precisely transferring small features onto substrates with small wavelength lithography, and existing electrode assemblies fail to effectively control the electric field for improved exposure and development resolution.
Innovation Solution
A substrate processing apparatus is designed with a chamber body, a pedestal, and electrodes to apply an electric field to the photoresist layer through an intermediate medium, such as a slurry or liquid solution, to control the diffusion of charged species and enhance the accuracy and sensitivity of the photolithography process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If small wavelength lithography is used to reduce minimum printable size, then manufacturing precision is improved, but productivity decreases and line edge roughness increases
Solution Approach 1:
An intermediate medium (liquid or slurry) is introduced between the electrode assembly and the photoresist layer to enable effective electric field application. This intermediary allows the electric field to penetrate and control charged species diffusion during post-exposure bake, thereby improving line edge profile and resist sensitivity without requiring smaller wavelengths, thus maintaining productivity while achieving better precision
Solution Approach 2:
The invention changes the physical and chemical parameters of the photoresist layer by applying an electric field during post-exposure bake. This field control modifies the diffusion characteristics of charged species in the photoresist, improving line edge roughness and resolution without changing the lithography wavelength, thus avoiding the productivity penalty associated with small wavelength lithography
2Manufacturing precision
If small wavelength lithography is used to transfer smaller features, then manufacturing precision is improved, but line edge roughness increases
Solution Approach 1:
The intermediate medium serves as a conductor that allows the electric field to effectively interact with the photoresist layer. This enables precise control of charged species migration during post-exposure bake, smoothing line edges and reducing roughness while maintaining the feature transfer accuracy achieved by small wavelength lithography
Solution Approach 2:
An electric field is applied during post-exposure bake to counteract the random diffusion of charged species that causes line edge roughness. This preliminary control action prevents the formation of rough line edges before the development process, thereby reducing line edge roughness while maintaining manufacturing precision
3Manufacturing precision
If electrode assembly is used to generate electric field for improving resolution, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The intermediate medium simplifies the electrode assembly design by eliminating the need for direct contact between electrodes and the photoresist layer. The liquid or slurry medium provides the necessary electrical conductivity and field penetration while allowing the use of simpler electrode structures, thus reducing device complexity while maintaining improved resolution
Solution Approach 2:
The intermediate medium serves multiple functions: it provides electrical conductivity for electric field application, acts as a processing fluid for post-exposure bake, and facilitates heat transfer. This multi-functionality reduces the need for separate systems, thereby reducing device complexity while achieving improved exposure development resolution
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 controlled electric field improves the line edge profile and resist sensitivity, reducing line edge/width roughness and increasing the productivity of photolithography processes by guiding charged species in desired directions, thereby enhancing the precision and accuracy of feature transfer.
Implementation Method 1
an electrode assembly is utilized to generate an electric field to a photoresist layer disposed on the substrate prior to or after an exposure process so as to modify chemical properties of a portion of the photoresist layer
Implementation Method 2
Exposure to light may decompose the photo acid generator, which generates acid and results in a latent acid image in the resist resin
Implementation Method 3
A substrate processing apparatus is designed with a chamber body, a pedestal, and electrodes to apply an electric field to the photoresist layer through an intermediate medium, such as a slurry or liquid solution
Data Source
AI summary
Embodiments described herein relate to methods and apparatus for performing immersion field guided post exposure bake processes. Embodiments of apparatus described herein include a chamber body defining a processing volume. A pedestal may be disposed within the processing volume and a first electrode may be coupled to the pedestal. A moveable stem may extend through the chamber body opposite the pedestal and a second electrode may be coupled to the moveable stem. In certain embodiments, a fluid containment ring may be coupled to the pedestal and a dielectric containment ring may be coupled to the second electrode.