Diffractive Beam Splitter for Substrate Deformation Metrology
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Solution Overview
Problem
Existing multi-spot local slope metrology techniques using etalons suffer from intensity variations in output beams, complicating accuracy and design, and are limited to measuring symmetrically spaced substrate deformations.
Innovation Solution
A metrology system employing a diffractive beam splitter to generate beams spaced apart, which are reflected and measured for positional information, allowing for improved accuracy and the ability to create and customize 2-dimensional arrays without the limitations of etalons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multi-spot local slope metrology uses etalons to generate multiple beams, then multiple beams can be directed to different spots on the substrate, but intensity variations occur in the output beams reducing measurement accuracy
Solution Approach 1:
The patent uses a diffractive optical element to create multiple copies of the input beam, each directed to a different spot on the substrate. This copying approach eliminates the intensity variation problems associated with etalon-based systems while maintaining the multi-spot measurement capability. The diffractive element generates precise beam positions through diffraction patterns rather than multiple reflections.
Solution Approach 2:
The patent replaces the mechanical/physical etalon structure with a diffractive optical element that uses wave optics principles. This substitution eliminates the complexity of aligning and maintaining multiple etalons while achieving the same multi-beam output with improved intensity uniformity and measurement accuracy.
2Adaptability or versatility
If etalons are used to create 2-dimensional arrays of output beams, then multiple spots can be measured, but the optical design becomes more complicated requiring multiple etalons
Solution Approach 1:
The patent combines multiple beam-generating functions into a single diffractive optical element. This single element can generate 2-dimensional arrays of beams by incorporating appropriate diffraction patterns, eliminating the need for multiple separate etalons and simplifying the overall optical design while maintaining full multi-spot measurement capability.
Solution Approach 2:
The diffractive optical element serves multiple functions simultaneously: it generates multiple beams, positions them in 2-dimensional arrays, and maintains uniform intensity across all beams. This universal element replaces what would otherwise require multiple specialized components, reducing system complexity while enhancing versatility.
3Adaptability or versatility
If etalon reflections create output beams, then multiple beams are generated, but the beam spacing follows a distinct pattern limiting measurement of asymmetric deformations
Solution Approach 1:
The patent employs asymmetric diffractive patterns in the optical element to generate beam arrays that can accommodate asymmetric substrate deformations. By designing the diffractive structure with specific asymmetric features, the system can measure both symmetric and asymmetric deformation patterns with equal precision, overcoming the limitations of etalon-based symmetric beam spacing.
Solution Approach 2:
The patent changes the fundamental parameter of beam generation from etalon reflection patterns to diffractive patterns. This parameter change allows for flexible control of beam spacing and positioning, enabling accurate measurement of various deformation patterns including asymmetric ones, while improving slope calculation accuracy through more precise beam position control.
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
This approach simplifies slope calculations, enhances design simplicity, and enables the measurement of both symmetric and asymmetric substrate deformations, improving device performance and yield.
Implementation Method 1
transmitting a first plurality of beams from a diffractive beam splitter to a first surface of a substrate
Implementation Method 2
a lens positioned between the beam splitter and the substrate support, the lens adapted to focus the second plurality of beams on a first surface of the substrate
Implementation Method 3
to generate a reflection of a second plurality of beams
Data Source
AI summary
Embodiments of the disclosure provide methods and system for inspecting and treating a substrate. In one embodiment, a method is provided including transmitting a first plurality of beams from a diffractive beam splitter to a first surface of a substrate to generate a reflection of a second plurality of beams, wherein the first plurality of beams are spaced apart from each other upon arriving at the first surface of the substrate; receiving the second plurality of beams on a recording surface of an optical device, wherein the second plurality of beams are spaced apart from each other upon arriving at the recording surface; measuring positional information of the second plurality of beams on the recording surface; comparing the positional information of the second plurality of beams to positional information stored in a memory; and storing a result of the comparison in the memory.