Metal Oxide Photoresist Cyclic Development to Deter Etch Stop
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Solution Overview
Problem
Current photolithography processes face challenges in achieving reliable and reproducible resolution of small features due to the use of 193 nm UV light, which requires complex techniques and results in issues such as low power output, light loss during patterning, and high aspect ratios leading to pattern collapse in conventional organic chemically amplified resists used in EUV lithography.
Innovation Solution
A method involving alternating pulses of etchant and oxidizing agent, or etchant followed by a wash agent, is used to develop metal or metal oxide-based thin film photoresists post-EUV exposure, effectively removing non-volatile species and forming a resist mask.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional organic chemically amplified resists are used in EUV lithography, then the photoresist can be developed using standard wet development processes, but the resist exhibits low absorption coefficients in EUV region and produces blur or line edge roughness due to diffusion of photo-activated chemical species
Solution Approach 1:
The patent changes the material composition parameter from conventional organic CAR to metal oxide-based resist, which fundamentally alters the absorption characteristics and eliminates diffusion-related blur while maintaining compatibility with EUV lithography processes
Solution Approach 2:
The invention uses composite material structures combining metal oxides with specific organic components to create a photoresist that achieves both high EUV absorption and sharp patterning, resolving the contradiction between absorption coefficient and line edge quality
2Strength
If conventional CAR materials are used to provide etch resistance for underlying device layers, then the required etch resistance can be achieved, but small features result in high aspect ratios at risk of pattern collapse
Solution Approach 1:
The patent changes the resist material from conventional CAR to metal oxide-based composition, which provides inherent etch resistance while maintaining structural integrity at small dimensions, thereby preventing pattern collapse without requiring excessive thickness
Solution Approach 2:
The invention employs curved or tapered sidewalls in the patterned features through controlled development processes, which distributes mechanical stress and prevents collapse of high aspect ratio structures while maintaining etch resistance
3Ease of manufacture
If 193 nm UV light is used for photolithography, then the existing photoresist materials can be effectively exposed, but the wavelength is significantly greater than desired feature sizes requiring complex resolution enhancement techniques
Solution Approach 1:
The patent changes the lithography wavelength parameter from 193 nm to EUV region (13.5 nm), which directly enables sub-10 nm feature fabrication while the metal oxide-based photoresist material is specifically designed to be compatible with this new wavelength, eliminating the need for complex resolution enhancement techniques
4Manufacturing precision
If EUV photolithographic processes are implemented, then shorter wavelength light enables smaller feature sizes, but low power output and loss of light during patterning occur
Solution Approach 1:
The patent changes the photoresist material parameters to have higher EUV absorption coefficients, which improves photon utilization efficiency and reduces light loss during patterning, thereby compensating for the low power output of EUV sources and enabling effective patterning with available flux
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
This method enhances etch resistance and resolution by eliminating non-volatile byproducts, reducing line edge roughness, and preventing pattern collapse, thereby improving the reliability and reproducibility of EUV lithography processes.
Implementation Method 1
developing the photopatterned metal-containing resist by selectively removing a portion of the photopatterned metal-containing resist by exposing the photopatterned metal-containing resist to at least one cycle including a pulse of an etchant
Implementation Method 2
a pulse of an oxidizing agent, delivered alternately, to form a resist mask... non-volatile byproducts of the pulse of the etchant are removed from the photopatterned metal-containing resist
Data Source
AI summary
Provided are processes for development of photopatterned metal or metal oxide-based thin film photoresists post-EUV exposure for removal of non-volatile species and deterring etch stop. Repeated cycles of alternating treatment with an etchant and an oxidizing agent; or treatment with an etchant followed by treatment with a wash agent are effective techniques for removal of the undesired unexposed portion of a photoresist.