Slab Amplifier Aperture Plates Block Spontaneous Emission
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Solution Overview
Problem
Self-oscillation occurs in slab amplifiers used in EUV light generation apparatuses, hindering the amplification of seed beams due to reflection of spontaneous emission light by windows and holders, leading to difficulties in achieving precise pattern transfer in lithography processes.
Innovation Solution
The implementation of aperture plates with designed openings to block spontaneous emission light, inclined window holders to reduce reflected light incidence, and containers with labyrinthine structures to absorb reflected light, thereby minimizing self-oscillation and enhancing beam amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If windows and holders are used to seal the chamber, then the chamber is sealed properly, but self-oscillation occurs due to reflection of spontaneous emission light
Solution Approach 1:
An aperture plate is introduced as an intermediary component between the window and the discharge region. This aperture plate selectively transmits the seed beam while blocking spontaneous emission light, thereby preventing self-oscillation without compromising the sealing function of the window system
Solution Approach 2:
The aperture plate is positioned at a specific location where it can differentiate between the seed beam and spontaneous emission light. By creating a localized aperture with specific dimensions, the system allows the desired beam to pass while blocking harmful reflected light in other directions
2Object-generated harmful factors
If aperture plates are added to block spontaneous emission light, then self-oscillation is reduced, but device complexity increases
Solution Approach 1:
The aperture plate performs multiple functions simultaneously: it blocks spontaneous emission light to prevent self-oscillation, defines the beam path for the seed beam, and maintains the structural integrity of the chamber assembly. This multi-functionality reduces the need for additional separate components
3Object-generated harmful factors
If window holders are inclined to reduce reflected light, then self-oscillation is minimized, but manufacturing precision requirements increase
Solution Approach 1:
The window holders are pre-inclined at a specific angle during manufacturing to proactively redirect reflected light away from the discharge region. This preliminary geometric adjustment prevents self-oscillation before the problem can occur, eliminating the need for complex active control mechanisms
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
These measures significantly reduce self-oscillation, allowing for more effective amplification of seed beams and improved pattern transfer accuracy by minimizing reflected light within the discharge region, with self-oscillation output reduced to about 1/15 to 1/10 of original levels depending on the configuration.
Implementation Method 1
a first aperture plate provided between the first window and the electrodes, and having an opening of a dimension equal to or greater than a cross-section of the seed beam and equal to or smaller than a dimension of the first window; and a second aperture plate provided between the second window and the electrodes
Implementation Method 2
an optical system provided in the chamber to allow the seed beam having entered from the first window into the space between the pair of electrodes to be repeatedly reflected between the space
Implementation Method 3
a chamber having a first through-hole and a second through-hole and accommodating a laser gain medium; so that the seed beam is amplified to be an amplified beam
Data Source
AI summary
There is provided a slab amplifier including an optical system (48, 51) provided in a chamber (47) to allow a seed beam having entered from a first window into the space between a pair of electrodes (42, 43) to be repeatedly reflected between the space so that the seed beam is amplified to be an amplified beam; a first aperture plate (61) provided between the first window and the electrodes, and having an opening of a dimension equal to or greater than a cross-section of the seed beam and equal to or smaller than a dimension of the first window; and a second aperture plate (62) provided between the second window and the electrodes, and having an opening of a dimension equal to or greater than a cross-section of the amplified beam and equal to or smaller than a dimension of the second window.