Tilted-Substrate Multi-Wavelength Exposure for Thick Resist Focus
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Solution Overview
Problem
Existing exposure technologies struggle to achieve sufficient extension of focal depth in projection optical systems for thick film processes in semiconductor manufacturing, particularly with the use of multi-wavelength exposure and FLEX methods, as the demands for deeper focus have increased with thicker resist layers.
Innovation Solution
An exposure apparatus that combines the FLEX method with multi-wavelength exposure by inclining the substrate relative to the optical axis and adjusting the angle of gradient and wavelength difference to enhance focal depth, using a control unit to manage these parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If multi-wavelength exposure or FLEX method is used to extend focal depth, then the focal depth is extended to some extent, but the extension is insufficient for modern thick resist layers
Solution Approach 1:
The patent combines the FLEX method (exposing at multiple defocus states) with multi-wavelength exposure (using light at two different wavelengths) to achieve synergistic extension of focal depth. By merging these two techniques, the system achieves greater focal depth extension than either method alone, enabling accurate pattern formation in thick resist layers that neither method could achieve independently.
Solution Approach 2:
The patent changes multiple parameters simultaneously: it uses two different wavelengths of light (wavelength parameter), exposes at multiple defocus states (focus parameter), and scans the substrate in a tilted state (orientation parameter). By coordinating changes in these parameters, the system extends focal depth while maintaining pattern formation accuracy in thick resist.
2Length of moving object
If the substrate is scanned in a tilted state with coordinated wavelength and angle adjustments, then focal depth is significantly extended, but the system complexity increases
Solution Approach 1:
The patent employs a control unit that coordinates and adjusts multiple parameters (wavelength difference, substrate tilt angle, scanning speed, defocus states) based on their interrelationships. This feedback control ensures that as one parameter changes, other parameters are adjusted accordingly to maintain optimal exposure conditions, managing the system complexity through intelligent coordination rather than simple independent 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
This approach effectively doubles or multiples the focal depth by combining FLEX and RELAX methods, enabling accurate pattern formation in thicker resist layers, thus addressing the limitations of previous technologies.
Implementation Method 1
an optical projection system that exhibits on-axis chromatic aberration and that is configured to form a pattern image of the original at a plurality of positions in an optical axis direction of the optical projection system using the exposure light
Implementation Method 2
an illumination optical system configured to guide exposure light to the original, the exposure light including first exposure light with a first wavelength and second exposure light with a second wavelength that is different from the first wavelength
Data Source
AI summary
An exposure apparatus, which is configured to expose a substrate to light using an original in which a pattern is formed, includes an illumination optical system configured to guide exposure light to the original, the exposure light including first exposure light with a first wavelength and second exposure light with a second wavelength that is different from the first wavelength, an optical projection system that exhibits on-axis chromatic aberration and that is configured to form a pattern image of the original at a plurality of positions in an optical axis direction of the optical projection system using the exposure light, and a control unit configured to expose the substrate to light while scanning the substrate in a state where a normal direction of a surface of the substrate is inclined with respect to the optical axis direction of the optical projection system.