Optical Grating Metrology with Beam Splitting and Aperture Noise Filtering
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Solution Overview
Problem
Conventional systems face challenges in accurately and repeatedly measuring optical device structures on non-opaque substrates due to reflection and diffraction of light, leading to decreased accuracy and repeatability.
Innovation Solution
A metrology measurement system is developed, comprising a substrate support, optical arm, and detector arm, equipped with a light source, lenses, beam splitters, apertures, and detectors, which utilize beam splitters and apertures to filter out noise and enhance image symmetry, enabling precise measurement of grating pitch and orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement systems are used to measure optical device structures on non-opaque substrates, then the measurement process is simple, but the accuracy and repeatability decrease due to reflection and diffraction of light
Solution Approach 1:
The patent converts the harmful effects of light reflection and diffraction into beneficial signals. By using a beam splitter to separate reflected light from transmitted light, and employing diffraction gratings to create measurable diffraction patterns, the system transforms these previously harmful phenomena into the basis for accurate measurement of optical device structures on non-opaque substrates
Solution Approach 2:
The patent introduces several intermediary elements including a beam splitter, diffraction grating, and aperture as mediators between the light source and the detector. These intermediaries manage the complex light interactions by separating different light paths and filtering out unwanted reflections and diffractions, enabling accurate measurement despite the non-opaque nature of the substrate
2Measurement precision
If beam splitters and apertures are added to filter noise and enhance image symmetry, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent segments the optical measurement system into distinct functional modules: a beam splitter that divides light paths, an aperture that filters specific light, and a detector that captures measurement data. This segmentation allows each component to address specific measurement challenges independently, improving overall measurement repeatability while making the system more manageable despite increased complexity
Solution Approach 2:
The patent deliberately introduces asymmetric elements into the optical path, such as positioning the aperture and beam splitter at specific asymmetric locations to optimize the separation of reflected and transmitted light. This asymmetric arrangement enhances image symmetry in the final measurement by compensating for asymmetric reflections and diffractions from the non-opaque substrate
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 achieves enhanced accuracy and repeatability in measuring optical device structures by minimizing noise and interference, allowing for localized and precise imaging of gratings.
Implementation Method 1
a light source operable to project a first beam on a first light path
Implementation Method 2
The first lens is disposed on the first light path and between the substrate support and the light source
Implementation Method 3
The second lens focuses the second beam to a second beam diameter
Implementation Method 4
The first beam splitter is operable to allow the first beam projected on the first light path to the substrate support and operable to reflect a second beam on a second light path
Implementation Method 5
The aperture is disposed between the second lens and the first detector. The aperture operable to receive the second beam diameter of the second beam from the second lens
Implementation Method 6
The first detector is disposed on the second light path
Data Source
AI summary
The present disclosure relates to metrology measurement systems, and related methods. In one or more embodiments a system, includes a substrate support, and an optical arm. The optical arm includes a light source operable to project a first beam on a first light path. The optical arm also includes a first lens, a first beam splitter, a second lens, a first detector, and an aperture. The first lens is disposed on the first light path and between the substrate support and the light source. The first beam splitter is disposed on the first light path. The first beam splitter is positioned between the substrate support and the light source. The first detector is disposed on the second light path. The second lens focuses the second beam to a second beam diameter. The aperture is disposed between the second lens and the first detector.