UV Flood Exposure Dose Homogenization via Dynamic Rotation
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Solution Overview
Problem
High power UV flood exposure systems often suffer from significant dose non-uniformity across the exposed area and over time, leading to inconsistencies in substrate processing, particularly in photolithography and semiconductor manufacturing, where achieving uniformity is crucial for quality and efficiency.
Innovation Solution
The method employs a combination of rotation, translation, and variable processing conditions, utilizing in-situ photo-sensors to real-time map source power and non-uniformity, and adjusts settings such as substrate rotation rate, UV source scanning rate, power, distance, aperture, and angle of incidence to achieve a selected dose profile, thereby homogenizing the exposure dose across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high power UV flood exposure source is used to increase throughput, then productivity is improved, but dose uniformity deteriorates (non-uniformity can be >5% and sometimes >10%)
Solution Approach 1:
The patent applies dynamics by making the substrate rotation speed variable rather than constant. The rotation speed is dynamically adjusted based on the radial position during exposure, with different rotation speeds applied at different radii to compensate for the non-uniform intensity distribution of the UV source. This dynamic adjustment allows the system to maintain high throughput while achieving uniform dose distribution across the substrate.
Solution Approach 2:
The patent changes the parameter of rotation speed as a function of radial position. By varying the rotation speed parameter across different radii (faster at outer radii, slower at inner radii), the system compensates for the intensity fall-off of the UV source. This parameter change approach enables simultaneous achievement of high productivity and dose uniformity.
2Ease of manufacture
If low cost high power UV flood options are used, then cost is reduced, but dose uniformity deteriorates (non-uniformity can be >5% and sometimes >10%)
Solution Approach 1:
The patent uses parameter changes (variable rotation speed as a function of radius) to compensate for the inherent non-uniformity of low-cost UV flood sources. By adjusting the rotation speed parameter across different radial positions, the system achieves dose uniformity without requiring expensive uniformity-corrected hardware, thereby maintaining cost-effectiveness while improving manufacturing precision.
3Productivity
If high power UV source is used to increase throughput, then productivity is improved, but dose control through time deteriorates (drifting average power through time)
Solution Approach 1:
The patent implements feedback by using photo-sensors to measure the actual UV intensity at different radial positions during exposure. This feedback information is used to dynamically adjust the rotation speed to compensate for power drift and maintain consistent dose delivery over time. The feedback mechanism ensures reliable dose control even when using high-power sources that may exhibit temporal instability.
4Manufacturing precision
If rotation and variable speed control is implemented to improve dose uniformity, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent uses feedback from photo-sensors to simplify the control complexity. Rather than requiring complex pre-calculated variable speed profiles, the system uses real-time feedback to automatically adjust rotation speed based on measured intensity distribution. This feedback-based approach reduces control complexity while achieving the desired manufacturing precision.
Solution Approach 2:
The system performs self-service by using the photo-sensors to automatically characterize the UV source intensity distribution and self-adjust the rotation speed profile accordingly. This self-characterization and self-adjustment capability reduces the need for external calibration and complex control algorithms, thereby reducing overall system complexity while maintaining high manufacturing precision.
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 significantly reduces dose non-uniformity to less than 0.5%, ensuring consistent exposure and improving processing uniformity, making it applicable to various radiation-based processes with inherent source non-uniformities.
Implementation Method 1
utilizing in-situ photo-sensors to real-time map source power and non-uniformity
Implementation Method 2
a substrate may be exposed to ultraviolet (UV) light, including high power UV radiation
Data Source
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AI summary
A substrate may be disposed on a substrate support in a flood exposure treatment system. A flood exposure dose profile may be selected. The substrate may be exposed to flood irradiation from a source, and the flood irradiation may be terminated when the selected flood exposure dose profile is achieved. Exposing the substrate to flood irradiation may comprise controlling at least one of a substrate rotation rate, a source scanning rate, a substrate scanning rate, a source power setting, a distance from the source to the substrate, a source aperture setting, an angle of incidence of flood irradiation on the substrate, and a source focus position to achieve the selected flood exposure dose profile.