Laser-Sustained Plasma Optics for Uniform Broadband Brightness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Laser sustained plasma sources exhibit fluctuating brightness due to turbulence in the neutral gas flow and pump laser instabilities, limiting the performance of semiconductor metrology and inspection tools.
Innovation Solution
An illumination source system using active and passive optics to adjust and combine broadband light beams, including an adjustable reflector and beamsplitter, to maintain brightness distribution and improve uniformity without reducing peak intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback control loop is used to reduce fluctuations by controlling laser power, then temporal noise is reduced, but brightness is reduced because the source cannot operate at peak intensity
Solution Approach 1:
The patent extracts the fluctuation correction function from the laser power control to a separate optical path correction mechanism. The adjustable optics (mirrors, lenses) independently correct spatial and temporal fluctuations in the light beam without requiring reduction of laser power, thus maintaining peak brightness while reducing noise.
Solution Approach 2:
The patent introduces adjustable optics as an intermediary between the laser source and the plasma. These optics act as a mediator that corrects beam fluctuations without affecting the laser power itself, allowing the system to maintain high brightness while reducing temporal noise through optical path stabilization.
2Reliability
If laser is shined vertically opposite to gravity with horizontal bulb mounting, then fluctuations are reduced, but design geometry is constrained
Solution Approach 1:
The patent replaces fixed geometric constraints with dynamic, adjustable optics that can adapt to different orientations and configurations. The adjustable mirrors and lenses allow the system to compensate for fluctuations regardless of the bulb's mounting orientation, eliminating the need for specific vertical/horizontal geometry constraints.
Solution Approach 2:
The patent changes the approach from fixing geometric parameters (orientation) to adjusting optical parameters (mirror angles, lens positions). This allows the system to achieve fluctuation reduction through optical parameter adjustments rather than being constrained by fixed geometric mounting requirements.
3Reliability
If feedback control limits laser power to controllable regime, then noise is controlled, but peak brightness is not achieved
Solution Approach 1:
The patent segments the noise control function from the power control function. The laser operates at peak power independently, while separate adjustable optics handle the noise control by correcting beam fluctuations. This segmentation allows both peak brightness and noise control to be achieved simultaneously without compromising either.
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
The system reduces fluctuations and enhances brightness uniformity, improving the performance of semiconductor tools by maintaining peak brightness and achieving stringent uniformity requirements.
Implementation Method 1
an adjustable reflector configured to receive and reflect the broadband light beam emitted from the laser sustained plasma light source
Implementation Method 2
the detector may be configured to detect a brightness distribution of the broadband light beam emitted by the laser sustained plasma light source
Data Source
AI summary
An illumination source and method are disclosed for improving brightness uniformity. The illumination source may include a laser sustained plasma light source configured to generate a broadband light beam. The illumination source may include an adjustable reflector configured to be adjusted based on one or more signals indicative of a brightness distribution of the broadband light beam emitted along one or more directions. The illumination source may include a set of optics. The set of optics may be configured to split the broadband light beam into a first and second broadband light beam, invert the second broadband light beam, and recombine the first and second broadband light beam. The set of optics may be configured to image the illumination source at least twice, to receive a first and second broadband light beam and then combine the first and second broadband light beam.