Laser Reflectometry Wavelength Segmentation and Filtering
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Solution Overview
Problem
Conventional laser annealing processes face challenges due to interference between laser emitters and metrology lasers, leading to inaccurate metrology information and safety risks for personnel adjusting the beams, as the intensity of the semiconductor laser is harmful and requires protective gear that can obscure views.
Innovation Solution
A system with a chamber containing a process laser and a metrology system, where the process laser emits a beam at one wavelength and the metrology laser emits a beam at a different wavelength, using filters to minimize interference and a secondary filter to safely attenuate the metrology laser beam for personnel access, reducing cross-talk and ensuring safe adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If laser emitters are used for annealing, then thermal processing is achieved, but light from the laser emitter interferes with the semiconductor laser beam, altering beam properties and causing deviations in metrology information
Solution Approach 1:
The patent segments the optical spectrum by assigning different wavelengths to different functions: the process laser operates at one wavelength for thermal processing while the semiconductor laser operates at a different wavelength for metrology. This spectral segmentation eliminates interference between the two laser systems and allows simultaneous operation without cross-contamination of signals.
Solution Approach 2:
The patent introduces filters as intermediary elements that selectively transmit or block specific wavelengths. These filters act as mediators that allow the process laser light to pass through to the substrate while blocking it from reaching the sensor, and simultaneously allow the semiconductor laser light to reach the sensor for accurate metrology measurements.
2Measurement precision
If the semiconductor laser beam intensity is increased for effective metrology, then measurement capability is improved, but the beam becomes harmful to human vision and skin, requiring tinted safety glasses and protective clothing that obscure areas of interest
Solution Approach 1:
The patent introduces a filter as an intermediary element placed in the path of the semiconductor laser beam. This filter selectively transmits the laser wavelength needed for metrology while blocking harmful portions of the spectrum, allowing personnel to work safely without tinted safety glasses or protective clothing that would obstruct their view of the substrate.
Solution Approach 2:
The patent applies local quality by making the filter wavelength-selective: it is transparent at the specific wavelength of the semiconductor laser beam for metrology purposes while being opaque or attenuating at other wavelengths that would be harmful to personnel. This localized spectral filtering provides both measurement capability and safety without the need for obscuring protective gear.
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
Enhances metrology accuracy by minimizing unnecessary light interference and ensures safer operations by reducing the intensity of the metrology laser beam during adjustments, eliminating the need for tinted safety glasses and protective gear.
Implementation Method 1
the second laser device comprises a filter adapted to attenuate one or both of the first wavelength and the second wavelength
Implementation Method 2
the first and second filters are transparent to the primary beam and attenuate the process beam
Implementation Method 3
Light from the semiconductor laser is directed towards the substrate and the light reflected from the substrate is received by the sensor
Implementation Method 4
the light reflected from the substrate is received by the sensor
Implementation Method 5
Conventional laser annealing processes use laser emitters that may be semiconductor or solid state
Implementation Method 6
Semiconductor substrates are subjected to thermal processing in the context of many transformations, including doping, activation, and annealing
Data Source
AI summary
Embodiments of the present invention relate to methods and apparatus for control of laser devices and safety features related to utilization of laser devices in substrate processing systems. In one embodiment, a system for processing a substrate is provided. The system includes a chamber having a processing volume, a first laser device to emit a beam at a first wavelength into the processing volume, and a second laser device to emit a beam at a second wavelength into the processing volume, wherein the second wavelength is different than the first wavelength, and the second laser device comprises a filter adapted to attenuate one or both of the first wavelength and the second wavelength.