Optical Characterization of Patterned Samples for Asymmetry Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Accurate characterization of geometrical and material properties of microelectronic devices becomes increasingly challenging as critical dimensions shrink and devices become more complex, with conventional metrology methods struggling to detect asymmetry variations in patterned samples, such as tilting in periodic gratings and overlay inaccuracies.
Innovation Solution
A novel measurement technique that utilizes differential optical measurements by analyzing the optical response of patterned samples to different polarization states, allowing for the detection of asymmetry by comparing the polarization states of incident and reflected light, and determining the level and direction of asymmetry in patterned regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical reflectometry methods are used to characterize patterned samples, then general geometrical and material properties can be obtained, but asymmetry variations such as tilting in periodic gratings and overlay inaccuracies cannot be detected
Solution Approach 1:
The patent applies asymmetry by introducing a second measurement configuration that is asymmetric with respect to the first configuration. Specifically, the second illumination direction is oriented differently from the first illumination direction, creating an asymmetric measurement setup that enables detection of asymmetry variations in the sample that would be invisible to symmetric conventional methods
Solution Approach 2:
The patent adds another dimension to the measurement by performing measurements from multiple illumination directions and/or polarization states. This multi-dimensional approach transforms a single-point measurement into a multi-point characterization, enabling detection of asymmetry variations through comparison of measurements taken from different angular or polarization dimensions
2Manufacturing precision
If conventional optical reflectometry is applied to test structures with repeating arrays, then standard geometric parameters can be measured, but overlay inaccuracies and misalignment between patterned layers cannot be identified
Solution Approach 1:
The patent uses the differential optical response between two measurement configurations as an intermediary indicator of asymmetry. By comparing measurements from two different illumination directions or polarization states, the system creates a differential signal that serves as a sensitive mediator for detecting overlay inaccuracies and misalignment, converting subtle structural asymmetries into measurable optical differences
3Loss of information
If broadband light is shone on a sample and reflected light is collected, then information on geometry and material properties can be obtained, but polarization state variations and their relation to asymmetry cannot be analyzed
Solution Approach 1:
The patent segments the optical measurement into distinct polarization state components by performing measurements at different polarization states separately. This segmentation allows the system to analyze how the sample's optical response varies with polarization state, revealing asymmetry information that would be lost in a single integrated measurement, while keeping the system architecture relatively simple through sequential rather than simultaneous multi-state measurement
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
Enables precise characterization of patterned samples by identifying asymmetry, including tilted walls and overlay misalignments, thereby improving manufacturing process control and accuracy.
Implementation Method 1
directing illuminating light onto said patterned region along an illumination channel and collecting light reflected from said region propagating along a collection channel to be detected
Implementation Method 2
such that detected light has a polarization state different from polarization of the illuminating light
Data Source
AI summary
A method and system are presented for use in measuring on patterned samples, aimed at determining asymmetry in the pattern. A set of at least first and second measurements on a patterned region of a sample is performed, where each of the measurements comprises: directing illuminating light onto the patterned region along an illumination channel and collecting light reflected from the illuminated region propagating along a collection channel to be detected, such that detected light from the same patterned region has different polarization states which are different from polarization of the illuminating light, and generating a measured data piece indicative of the light detected in the measurement. Thus, at least first and second measured data pieces are generated for the at least first and second measurements on the same patterned region. The at least first and second measured data pieces are analyzed and output data is generated being indicative of a condition of asymmetry in the patterned region.