Cyclic Photoresist Development for Selective EUV Pattern Etching
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Solution Overview
Problem
The development and processing of inorganic-based resists for Extreme Ultraviolet (EUV) patterning in semiconductor manufacturing pose challenges due to their complex processing requirements and the need for high etch resistance and selectivity.
Innovation Solution
A method involving a cyclic development process in a process chamber, where a developing gas is flowed to etch unexposed portions of the photoresist film, followed by purging with a purging gas, and repeated multiple times at varying pressures and temperatures to achieve complete etching and high selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single-step etching process is used to develop inorganic-based photoresist, then the processing time is short, but the completeness and selectivity of the etching is insufficient
Solution Approach 1:
The etching process is divided into multiple discrete steps with alternating developing gas and purging gas flows. Each step targets specific portions of the photoresist (exposed or unexposed) with controlled etching duration and gas composition, enabling selective and complete removal while maintaining process control
Solution Approach 2:
The patent implements periodic alternation between developing gas flow (for etching) and purging gas flow (for clearing the chamber). This cyclic pattern repeats multiple times with varying parameters to achieve progressive removal of photoresist material while preventing unwanted etching and ensuring complete development
2Productivity
If continuous developing gas flow is used, then the etching speed is fast, but the selectivity and control over etching depth is reduced
Solution Approach 1:
The cyclic alternation between developing gas flow and purging gas flow creates periodic etching intervals. This allows rapid material removal during developing gas phases while the purging phases reset the environment, preventing uncontrolled etching and enabling precise depth control through multiple cycles
Solution Approach 2:
The patent dynamically adjusts etching parameters across multiple cycles, including gas flow rates, pressure, temperature, and etching duration. This dynamic control enables the process to adapt to the changing photoresist morphology, maintaining high etching speed while achieving the required selectivity and depth control
3Productivity
If high pressure is used during etching, then the etching rate increases, but the uniformity and control of the etching process decreases
Solution Approach 1:
The patent implements dynamic pressure control where the chamber pressure is adjusted across different etching cycles and within each cycle. Pressure is optimized for each specific etching step to balance etching rate and uniformity, with higher pressures used when faster removal is needed and lower pressures when uniformity is critical
Solution Approach 2:
The etching process is segmented into multiple steps, each with optimized pressure parameters. This allows the overall etching rate to be maintained high through cumulative effect of multiple steps while each individual step operates at optimal pressure for uniformity and 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 method enhances the completeness and selectivity of the developing etch process, allowing for effective patterning of inorganic-based resists regardless of the aspect ratio of the desired openings, while maintaining control over the development process.
Implementation Method 1
etching parts of the unexposed portions of the photoresist film with a developing gas
Implementation Method 2
purging the developing gas from the process chamber with a purging gas
Implementation Method 3
photons are emitted from a light source onto a photosensitive photoresist to initiate a chemical reaction
Data Source
AI summary
A method of processing a substrate includes receiving a substrate including a photoresist film including exposed and unexposed portions, etching parts of the unexposed portions of the photoresist film with a developing gas in a process chamber to leave a residual part of the unexposed portions, and purging the developing gas from the process chamber with a purging gas. After purging the developing gas, the residual part of the unexposed portions is etched with the developing gas. The substrate is etched using exposed portions of the photoresist film as a mask.