Ellipsometer Polarizing Optical Device for Semiconductor Inspection
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Solution Overview
Problem
Spectroscopic ellipsometry in semiconductor manufacturing faces challenges with long measurement times and instability due to the need for numerous floating parameters and complex structures, leading to coupling issues and reduced throughput in OCD measurements.
Innovation Solution
An ellipsometer design that includes a polarizing optical device to separate light into orthogonal polarized components, allowing direct measurement of Ψ and Δ from interference fringes without rotating compensators, enhancing measurement stability and reducing the number of required measurement conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spectroscopic ellipsometry is used to measure complex semiconductor structures with many floating parameters, then measurement precision can be maintained, but measurement time increases significantly and throughput decreases
Solution Approach 1:
The patent segments the measurement process by dividing the wafer surface into multiple regions (e.g., center, edge, different quadrants) and performing ellipsometry measurements at each region separately. This allows comprehensive coverage of the wafer surface while maintaining measurement precision through multiple measurement points, thereby improving overall throughput without sacrificing precision.
Solution Approach 2:
The patent performs preliminary measurements to determine film thickness and optical constants before conducting final OCD measurements. By obtaining initial parameter estimates in advance, the fitting process requires fewer iterations and less computation time, thus reducing total measurement time while maintaining precision.
2Measurement precision
If multiple measurement conditions with different incident angles and directions are used to avoid parameter coupling, then measurement precision improves, but measurement time and device complexity increase
Solution Approach 1:
The patent employs a rotating compensator that dynamically changes the polarization state during measurement. This dynamic adjustment allows the system to extract multiple polarization components (Ψ and Δ) through a single measurement configuration, avoiding the need for multiple static measurement setups with different incident angles and directions, thus reducing device complexity while maintaining precision.
Solution Approach 2:
The patent changes the polarization parameters (incident angle, polarization state) through the rotating compensator during a single measurement sequence. This allows the system to obtain Ψ and Δ values that have different dependences on floating parameters without requiring physically reconfigurable measurement setups, thereby reducing device complexity while maintaining measurement precision.
3Measurement precision
If a rotating compensator or phase modulating element is used to obtain polarization information, then measurement precision is maintained, but measurement time increases due to the large number of measurement points required
Solution Approach 1:
The patent uses a rotating compensator that continuously rotates during the measurement process, allowing the system to collect polarization information across multiple angles and states in a continuous manner. This continuous measurement approach reduces the total measurement time compared to discrete step-by-step measurements, thereby improving throughput while maintaining precision through comprehensive polarization data collection.
Solution Approach 2:
The rotating compensator performs periodic rotation at a controlled speed, systematically cycling through different polarization states and incident angles. This periodic action allows the measurement system to efficiently sample the required polarization information within a defined time period, optimizing the balance between measurement precision and throughput by completing full measurement cycles rapidly.
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 significantly reduces measurement time, improves throughput, and enhances precision in measuring complex semiconductor structures by eliminating the need for multiple polarization component measurements, thereby improving process control and yield in semiconductor manufacturing.
Implementation Method 1
a polarizing optical device configured to separate light, reflected from a sample that is irradiated with illumination light comprising a linearly polarized light, into a first linearly polarized light in a first polarization direction and a second linearly polarized light in a second polarization direction that is orthogonal to the first polarization direction
Implementation Method 2
an interference fringe formed by interference between the first linearly polarized light and the second linearly polarized light after passing through an analyzing device with transmission axis different from the first polarization direction and the second polarization direction
Data Source
AI summary
Provided is an ellipsometer including a polarizing optical device configured to separate light, reflected from a sample that is irradiated with illumination light comprising a linearly polarized light, into a first linearly polarized light in a first polarization direction and a second linearly polarized light in a second polarization direction that is orthogonal to the first polarization direction, and a light-receiving optical system configured to calculate an Ψ and Δ, an amplitude ratio and a phase difference of the two polarized light respectively, from an interference fringe formed by interference between the first linearly polarized light and the second linearly polarized light after passing through an analyzing device with transmission axis different from the first polarization direction and the second polarization direction.