Pulsed Light Spectral Control via Segmented Actuators
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Solution Overview
Problem
In semiconductor lithography, controlling the spectral features of pulsed light beams is challenging due to disturbances that affect the optical spectrum, leading to deviations from desired spectral characteristics, which impact the quality and efficiency of patterning microelectronic features on wafers.
Innovation Solution
A method and system that adjust the spectral features of pulsed light beams by regulating the operating characteristics of an optical source using a feedback loop, involving two actuatable apparatuses, where the first apparatus adjusts the timing and the second apparatus adjusts the optical magnification, allowing for precise control of spectral features like bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single actuatable apparatus is used to control spectral features, then the device complexity is low, but the control precision and speed are insufficient
Solution Approach 1:
The control system is segmented into two independent actuatable apparatuses: a first actuatable apparatus for coarse spectral feature control and a second actuatable apparatus for fine spectral feature control. This segmentation allows each apparatus to operate within its optimal control range, achieving high precision without requiring a single overly complex apparatus.
2Productivity
If traditional spectral control methods are used, then the system is stable, but the change state operation time is excessive
Solution Approach 1:
The first actuatable apparatus performs preliminary coarse adjustment of spectral features to reach near-target values quickly. This preliminary action reduces the adjustment range required by the second actuatable apparatus, enabling faster convergence to the target spectral state and reducing overall change state operation time.
Solution Approach 2:
The control system implements periodic measurement and adjustment cycles, where spectral features are measured at intervals and both actuatable apparatuses are adjusted in sequence. This periodic action allows the system to efficiently converge to target spectral values while maintaining stable operation during exposure processes.
3Measurement precision
If spectral feature measurements are performed for every pulse, then the control precision is high, but the measurement time and system complexity increase
Solution Approach 1:
Instead of measuring spectral features for every single pulse, the system performs measurements at selected intervals (partial action). This approach provides sufficient control precision by capturing spectral variations over time while avoiding the excessive measurement overhead and system complexity that would result from continuous per-pulse measurement.
Data Source
AI summary
A spectral feature of a pulsed light beam produced by an optical source is adjusted by receiving an instruction to change a spectral feature of the pulsed light beam from a value in a first target range to a value in a second target range; regulating a first operating characteristic of the optical source; determining an adjustment to a second actuatable apparatus of the optical source; and adjusting the second actuatable apparatus by an amount based on the determined adjustment. The first operating characteristic is regulated by adjusting a first actuatable apparatus of the optical source until it is determined that the first operating characteristic is within an acceptable range of values. The adjustment to the second actuatable apparatus is determined based at least in part on: a relationship between the adjustment of the first actuatable apparatus and a spectral feature of the light beam, and the second target range.