EUV Mirror Array Power Reduction for Stable Die Repair Exposure
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Solution Overview
Problem
Existing EUV radiation sources in lithographic apparatuses are difficult to control for power adjustments, leading to undesired fluctuations when attempting to reduce power for tasks like die repair.
Innovation Solution
A method involving rotating mirrors in a first array to redirect EUV radiation sub-beams onto a second array at positions that provide reduced transmission, allowing power reduction without altering the EUV radiation source output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the power provided to the laser and/or optical amplifiers is reduced to temporarily reduce EUV radiation power, then the EUV radiation power is reduced, but substantial fluctuations of the power of light delivered to the tin droplets are generated
Solution Approach 1:
The illumination system is divided into multiple mirror arrays (first array and second array) that can independently control different portions of the EUV radiation beam. This segmentation allows selective reduction of power to specific areas without affecting the overall beam stability or requiring changes to the laser source.
Solution Approach 2:
The mirror arrays serve as intermediary elements between the EUV radiation source and the patterning device. By adjusting the mirrors, power reduction is achieved through optical path modification rather than direct source control, thereby maintaining source stability while achieving the desired power reduction effect.
2Power
If mirrors of the first array are rotated to reduce transmission of sub-beams, then EUV radiation power incident on the patterning device is reduced, but transmission of the illumination system changes
Solution Approach 1:
The system applies different transmission characteristics to different portions of the illumination system. By selectively rotating specific mirrors in the first array, power reduction is applied locally to specific sub-beams or areas, while other portions of the illumination system maintain their original transmission characteristics, thus preserving overall illumination mode stability.
Solution Approach 2:
The mirror rotation angles are dynamically adjusted to achieve the desired power reduction while maintaining telecentricity. The system can adaptively control the degree of rotation to balance power reduction requirements with illumination mode stability, allowing flexible optimization of both parameters.
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
Effectively reduces EUV radiation power incident on the patterning device by up to 50% or more, maintaining telecentricity and minimizing illumination mode changes.
Implementation Method 1
a first array of mirrors being configured to receive EUV radiation and to reflect the EUV radiation as sub-beams of radiation towards the second array of mirrors
Implementation Method 2
rotating mirrors of the first array such that at least some of the sub-beams of radiation are incident on mirrors of the second array at positions which provide reduced transmission
Data Source
AI summary
A method of providing an additional EUV radiation exposure of part of a die on a substrate at a level of EUV radiation power which compensates for a previous low exposure, the method using EUV radiation power incident upon a patterning device of a lithographic apparatus, the lithographic apparatus comprising a first array of mirrors and a second array of mirrors, the first array of mirrors being configured to receive EUV radiation and to reflect the EUV radiation as sub-beams of radiation towards the second array of mirrors, wherein the method comprises rotating mirrors of the first array such that at least some of the sub-beams of radiation are incident on mirrors of the second array at positions which provide reduced transmission of the sub-beams of radiation to the patterning device.