EUV Target Image Capture Gain Control
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Solution Overview
Problem
Existing extreme ultraviolet (EUV) light generation systems face challenges in maintaining accurate target image capturing and plasma generation due to degradation of flash lamps and other components over time, leading to decreased background luminance and reduced measurement accuracy.
Innovation Solution
A target image capturing device with a delay circuit, illumination light source, image capturing unit, processing unit, and control unit that adjusts the gain of the light amplification unit based on measured background luminance, ensuring optimal timing and brightness for EUV light generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If flash lamp and other components are used continuously over time, then the system operates continuously for EUV light generation, but the components degrade leading to decreased background luminance and reduced measurement accuracy
Solution Approach 1:
The patent implements a feedback mechanism where the imaging device captures background images, the processing unit measures background luminance, and the control unit adjusts the flash lamp trigger timing and light amplification gain based on measured deviations from target luminance values. This closed-loop feedback system continuously compensates for component degradation, maintaining measurement accuracy despite extended operation time.
Solution Approach 2:
The system dynamically changes operational parameters including the flash lamp trigger delay time and the light amplification unit gain to compensate for component degradation. By adjusting these parameters based on real-time background luminance measurements, the system maintains optimal imaging conditions even as components age and performance degrades.
2Illumination intensity
If the flash lamp trigger timing is adjusted to compensate for degradation, then background luminance can be maintained, but the system complexity increases due to additional control mechanisms
Solution Approach 1:
The control unit performs multiple functions: it controls the flash lamp trigger timing, adjusts the light amplification gain, and coordinates the imaging device operation. By consolidating these control functions into a single multi-functional unit, the system maintains background luminance compensation capability while minimizing the increase in overall system complexity.
Solution Approach 2:
The system performs self-diagnosis and self-adjustment by automatically measuring its own background luminance and correcting deviations through automated parameter adjustments. This self-service capability reduces the need for external calibration and manual intervention, making the added complexity self-managing rather than burden-some.
3Illumination intensity
If the light amplification gain is increased to compensate for decreased background luminance, then measurement brightness is maintained, but noise and artifacts in the captured images increase
Solution Approach 1:
Instead of using a fixed high gain setting, the system dynamically adjusts the light amplification gain based on real-time background luminance measurements. This dynamic adjustment allows the system to use the minimum necessary gain to maintain target luminance levels, thereby reducing noise and artifacts while still compensating for component degradation.
Solution Approach 2:
The system changes the light amplification gain parameter in conjunction with flash lamp trigger timing adjustments. By coordinating these parameter changes, the system achieves background luminance compensation through optimized combinations of parameters rather than relying solely on high gain amplification, thus minimizing noise and image artifacts.
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 solution maintains consistent background luminance and improves target measurement accuracy by adjusting the delay time of the flash lamp trigger and the gain of the light amplification unit, compensating for component degradation and ensuring high-quality EUV light generation.
Implementation Method 1
an image capturing unit (101) including a light amplification unit and disposed to capture an image of a shadow of a target to be observed, which is generated when the target is irradiated with the light emitted from the illumination light source
Implementation Method 2
an illumination light source (102) configured to emit light based on the first trigger signal
Implementation Method 3
generating extreme ultraviolet light by irradiating a target supplied from a target supply unit into a chamber with a laser beam to generate plasma from the target
Implementation Method 4
exposing a photosensitive substrate to the extreme ultraviolet light in the exposure apparatus
Data Source
AI summary
A target image capturing device according to an aspect of the present disclosure includes a delay circuit configured to receive a timing signal from outside and output a first trigger signal at a timing delayed by a first delay time from the reception of the timing signal; an illumination light source configured to emit light based on the first trigger signal; an image capturing unit including a light amplification unit and disposed to capture an image of a shadow of a target to be observed, which is generated when the target is irradiated with the light emitted from the illumination light source; a processing unit configured to perform image processing including processing of measuring a background luminance from the image captured by the image capturing unit; and a control unit configured to perform control to adjust a gain of the light amplification unit based on the background luminance.