Dual-bulb UV Lamphead Control for Irradiance Uniformity
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Solution Overview
Problem
The existing UV curing processes face challenges in maintaining uniformity due to varying output levels of UV bulbs, which affects substrate processing uniformity, especially as bulbs near the end of their life and when not all bulbs in a chamber are replaced simultaneously.
Innovation Solution
The method involves determining a baseline irradiance and relative irradiances for UV lamps, using closed-loop control to adjust lamp outputs with correction or compensation factors, ensuring equal irradiances and maintaining process uniformity across substrates, even with chamber component degradation or cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If UV bulbs are used in a chamber for extended operation, then productivity is improved, but manufacturing precision deteriorates due to output changes affecting substrate uniformity
Solution Approach 1:
The patent implements a feedback control system where irradiance sensors continuously monitor the UV output from each bulb. The controller receives this feedback and automatically adjusts the power supplied to each bulb to maintain uniform irradiance across the substrate, compensating for bulb degradation during extended operation.
Solution Approach 2:
The system dynamically changes the operating parameters (power levels) of individual UV bulbs based on their actual output performance. By adjusting the power input to each bulb according to real-time irradiance measurements, the system maintains consistent substrate exposure even as bulbs age during extended productivity operations.
2Device complexity
If UV bulbs are replaced at different times, then device complexity is reduced, but manufacturing precision deteriorates due to non-uniform output levels within the same chamber
Solution Approach 1:
The feedback control system monitors irradiance from each bulb individually and adjusts power levels to compensate for differences in bulb age and output. This allows bulbs of different ages to coexist in the same chamber while maintaining uniform substrate processing.
Solution Approach 2:
The system applies individualized control to each UV bulb based on its specific performance characteristics. Each bulb receives customized power adjustment to achieve uniform overall output, allowing different bulbs (with different ages and degradation levels) to contribute equally to the process uniformity.
3Manufacturing precision
If closed loop control is implemented to adjust lamp outputs, then manufacturing precision is improved, but device complexity increases due to additional control mechanisms
Solution Approach 1:
The patent employs irradiance sensors positioned to measure UV output from each bulb, with signals fed to a controller that automatically adjusts power levels. This closed-loop feedback mechanism maintains uniform substrate exposure despite variations in bulb performance, achieving high manufacturing precision through automated control.
Data Source
AI summary
The present invention generally relates to methods of controlling UV lamp output to increase irradiance uniformity. The methods generally include determining a baseline irradiance within a chamber, determining the relative irradiance on a substrate corresponding to a first lamp and a second lamp, and determining correction or compensation factors based on the relative irradiances and the baseline irradiance. The lamps are then adjusted via closed loop control using the correction or compensation factors to individually adjust the lamps to the desired output. The lamps may optionally be adjusted to equal irradiances prior to adjusting the lamps to the desired output. The closed loop control ensures process uniformity from substrate to substrate. The irradiance measurement and the correction or compensation factors allow for adjustment of lamp set points due to chamber component degradation, chamber component replacement, or chamber cleaning.