EUV Exposure Timing Synchronization for Uniform Dose
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Solution Overview
Problem
In exposure apparatus using pulsed light sources that generate EUV light from plasma, there is a timing mismatch between the exposure apparatus and the light source, leading to non-uniform exposure due to the delay in EUV light generation, which affects the number of pulses at the scan start and end points, resulting in poor exposure uniformity.
Innovation Solution
An exposure apparatus with a control mechanism that synchronizes the light emission timing of the pulsed light with the drive timing of the photosensitive substrate stage by detecting the light emission timing and adjusting the target material supply timing, allowing for precise matching of exposure start or end points with the light emission timing, thereby ensuring uniform exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the light source generates pulsed light by producing plasma from intermittently supplied target material, then the light source can operate with simple timing control, but the exposure timing becomes mismatched with the stage drive timing, causing non-uniform exposure
Solution Approach 1:
The control means performs preliminary synchronization by detecting the light emission timing of the pulsed light source and adjusting the stage drive timing or light emission timing before exposure begins. This advance timing adjustment ensures that the exposure starting point and ending point are properly aligned with the light pulses, preventing the timing mismatch that would otherwise cause non-uniform exposure at the scan start and end points
Solution Approach 2:
The control means detects the actual light emission timing of the pulsed light source and uses this feedback information to adjust the stage drive timing or light emission timing. This closed-loop feedback mechanism ensures that the timing synchronization is based on actual light emission events rather than predetermined timing, thereby maintaining exposure uniformity despite variations in light source operation
2Device complexity
If the exposure apparatus uses fixed stage drive timing, then the stage control is simple, but the number of pulses at scan start and end points becomes deficient due to timing delay, deteriorating exposure uniformity
Solution Approach 1:
The stage drive timing is made dynamic by allowing the control means to adjust the timing based on detected light emission timing. Instead of using fixed predetermined timing, the stage drive timing can be shifted to synchronize with the actual light pulses, ensuring that the number of pulses is uniform across the entire exposure field including the scan start and end points
3Adaptability or versatility
If the light emission timing is not synchronized with exposure timing, then the light source operates independently, but the maximum delay reaches 1 ms at 1 kHz repetition frequency, causing pulse deficiency
Solution Approach 1:
The control means detects the actual light emission timing of the pulsed light source and uses this feedback to synchronize the stage drive timing or light emission timing. This feedback mechanism eliminates the timing delay by continuously monitoring and adjusting based on actual light emission events, ensuring that no pulses are missed at the scan start and end points
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 synchronization ensures good uniformity of exposure dose even when using pulsed light generated from plasma, by minimizing the delay and maintaining a consistent number of pulses within the exposure field, thus enhancing exposure uniformity and throughput.
Implementation Method 1
a light emitting means for generating pulsed light by producing plasma from a target material
Implementation Method 2
a droplet laser produced plasma X-ray source, which produces plasma by impinging laser light to the droplet target
Data Source
AI summary
An exposure apparatus and exposure method that produces plasma from a target material, generates pulsed light, and carries out exposure with the pulsed light.In particular, a light emitting source generates pulsed light by producing plasma from an intermittently supplied target material. A reticle stage holds a reticle that is irradiated by the pulsed light. A photosensitive substrate stage holds a photosensitive substrate irradiated by the pulsed light patterned by the reticle. A control means controls the photosensitive substrate stage so that, before exposing the photosensitive substrate begins, the timing between an exposure starting point or an exposure ending point and the light emission timing are matched based on the drive timing of the photosensitive substrate stage and the light emission timing of the pulsed light.