Deep-Ultraviolet Resist Condensation for Lithography Etching
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Solution Overview
Problem
Deep-ultraviolet lithography processes for microstructures and semiconductor devices face challenges in removing deep-ultraviolet resist and bottom anti-reflective coating materials without causing unwanted trenches or features in the spacer layer, which can lead to device performance degradation or failure due to the limitations of current wet-etching and ashing processes.
Innovation Solution
The method involves condensing the deep-ultraviolet resist using ultraviolet radiation before etching, reducing its volume by 5% or more, and then removing it through a controlled ashing process to maintain consistent ashing rates and minimize trench formation in the spacer layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If wet-etching process is used to remove DUV resist and BARC material, then the resist and BARC can be removed, but unwanted trenches and features are formed in the spacer layer causing device performance degradation
Solution Approach 1:
The patent applies preliminary action by performing UV irradiation on the DUV resist before the ashing process. This pre-treatment condenses the resist material, making it more susceptible to selective removal during ashing while protecting the spacer layer from unwanted etching. The UV irradiation step prepares the resist in advance to enable selective removal without forming trenches in the spacer layer.
Solution Approach 2:
The patent changes the physical-chemical parameters of the DUV resist by exposing it to UV radiation at specific wavelengths (200-400 nm). This parameter change transforms the resist from its original state to a condensed state with different etch selectivity, allowing it to be removed during ashing while the spacer layer remains protected. The UV dose and wavelength are controlled parameters that enable this selective removal.
2Loss of substance
If additional ashing process is performed to remove DUV resist and BARC material, then complete removal is achieved, but unwanted trenches and undercuts are formed in the spacer layer
Solution Approach 1:
The UV irradiation step serves as a preliminary action that modifies the DUV resist properties before ashing. By condensing the resist through UV exposure, the process enables complete resist and BARC removal while minimizing the harmful effect of trench formation in the spacer layer during the subsequent ashing step.
Solution Approach 2:
The patent applies local quality by creating different properties in different regions: the DUV resist is transformed through UV irradiation to have high etch susceptibility, while the spacer layer maintains its original properties and is protected from etching. This localized property differentiation enables selective removal of resist without damaging the spacer layer.
3Loss of substance
If typical wet clean process is used for I-line photoresist, then effective removal is achieved, but it is ineffective for DUV resist and BARC material
Solution Approach 1:
The patent changes the chemical and physical parameters of the DUV resist through UV irradiation, transforming it into a state that is susceptible to ashing removal. This parameter transformation makes the ashing process effective for DUV resist and BARC material, extending the versatility of the cleaning process to handle different resist types that were previously incompatible with standard wet clean 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
This approach effectively removes the deep-ultraviolet resist and bottom anti-reflective coating while reducing unwanted trench formation, ensuring the quality of subsequent structural elements and maintaining consistent ashing rates, thus enhancing the reliability and performance of microstructures and semiconductor devices.
Implementation Method 1
condensing the ultraviolet resist by applying an ultraviolet radiation to the deep-ultraviolet resist
Implementation Method 2
removing the condensed ultraviolet resist
Data Source
AI summary
In a lithography process using an ultraviolet process, the applied ultraviolet resist can be removed by intentionally condensing the ultraviolet resist before removing the ultraviolet resist.