Wavelength-Dependent Aperture Module for Faster Wafer Metrology
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Solution Overview
Problem
Existing metrology tools face inefficiencies in throughput due to the need to swap aperture plates for different wavelengths, leading to sub-optimal aperture usage and measurement delays, especially in scatterometry metrology tools used for measuring parameters on wafers.
Innovation Solution
A metrology tool with a module that automatically selects apertures based on the wavelength of the radiation by configuring the aperture size and shape to be dependent on the received radiation, allowing for simultaneous measurement with multiple wavelengths without plate swapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If aperture plates are swapped for different wavelengths, then measurement precision is improved, but productivity decreases due to measurement delays
Solution Approach 1:
The patent applies the dynamics principle by making the aperture plate movable and adjustable. The aperture plate can be dynamically repositioned to different locations (first, second, third locations) corresponding to different wavelengths, eliminating the need to swap entire plates. This dynamic adjustment mechanism maintains measurement precision for different wavelengths while significantly improving throughput by reducing the time required to change apertures.
Solution Approach 2:
The patent segments the aperture plate into multiple independent aperture openings, each optimized for specific wavelength ranges. Instead of using separate complete aperture plates for different wavelengths, the single plate contains multiple segmented apertures that can be selectively activated by positioning. This segmentation allows rapid switching between wavelength-specific apertures without physical plate changes, resolving the contradiction between precision and productivity.
2Adaptability or versatility
If aperture plates are swapped for different wavelengths, then adaptability is improved, but device complexity increases due to plate swapping mechanisms
Solution Approach 1:
The patent merges multiple aperture openings onto a single aperture plate, with each aperture optimized for different wavelength ranges. This consolidation eliminates the need for multiple separate aperture plates and their associated swapping mechanisms. The single plate with multiple apertures provides the same adaptability across different wavelengths while significantly reducing device complexity by removing the mechanical swapping system.
3Measurement precision
If aperture plates are swapped for different wavelengths, then measurement precision is improved, but loss of time increases due to plate swapping
Solution Approach 1:
The patent implements preliminary action by pre-positioning multiple aperture openings on a single plate at locations optimized for different wavelengths. The aperture plate is designed in advance with all necessary apertures for various wavelength ranges already in place. During measurement, the system simply needs to reposition the plate to the appropriate location rather than swapping entire plates, thereby maintaining precision while minimizing time loss.
Data Source
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AI summary
A metrology tool for determining one or more parameters of interest (e.g. overlay) of a structure on an object (e.g. a wafer). The metrology tool comprises: a module for at least partially defining an aperture; projection optics; detection optics; and a detector. The module for at least partially defining an aperture is positionable so as to receive a radiation beam and to transmit a modified radiation beam. The projection optics is arranged to project modified radiation output by the module onto a beam spot region in which the structure is positionable. The detection optics is arranged to receive at least a portion of radiation scattered by the structure. The detector is operable to determine one or more parameters from the received scattered radiation. The module is configured such that a size and/or shape of the aperture defined by the module is dependent on a wavelength of the received radiation.