Lithography Dose Sensing for Beam Misalignment and Clipping
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Solution Overview
Problem
Existing dose control systems in EUV lithographic apparatuses struggle to accurately measure and control the dose of radiation beams due to the small spot size produced by mirrors with multiple segments, rendering edge measurements inadequate.
Innovation Solution
A dose control system with an energy sensor comprising a first sensor area to measure intensity and at least one second sensor area to measure misalignment or clipping, determining a difference between these measurements to control the radiation dose accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If an illuminator mirror with multiple segments is used to generate multiple spots, then the coverage area and patterning capability are improved, but the spot size per segment becomes small, making edge measurements inadequate for accurate dose control
Solution Approach 1:
The sensor is divided into multiple sensor areas (first sensor area for intensity measurement, second sensor area for misalignment/clipping measurement) to simultaneously capture different aspects of the radiation beam characteristics, enabling accurate dose control despite small spot sizes from segmented mirrors
Solution Approach 2:
The second sensor area acts as an intermediary to measure misalignment or clipping effects that indirectly affect the dose, allowing the system to compensate for positioning errors and maintain measurement accuracy even when the primary intensity measurement from the first sensor area is insufficient due to small spot size
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
Enables precise dose control by accounting for both intensity and misalignment or clipping effects, ensuring accurate patterning on substrates.
Implementation Method 1
an energy sensor arranged at a periphery of the slit
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A dose control system to control a dose of a radiation beam comprises an energy sensor comprising a first sensor area to measure an intensity of the radiation beam, and at least one second sensor area to measure an impact of misalignment or clipping of the radiation beam on the intensity of the radiation beam. The dose control system further comprises a control device to determine a difference between the measured intensity of the radiation beam and the measured impact of misalignment or clipping of the radiation beam on the intensity of the radiation beam, and control a dose of the radiation beam on the basis of the determined difference.