Multi-Layer Overlay Patterns for Reflectometry Measurement
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Solution Overview
Problem
As semiconductor device dimensions shrink, accurate measurement of overlay and critical dimensions becomes increasingly difficult, necessitating the development of new techniques to ensure proper alignment and sizing of patterned layers, as misalignments can lead to device failure.
Innovation Solution
The use of reflectometry techniques, including scatterometry and ellipsometry, to measure parameters such as overlay and critical dimensions by analyzing light reflected from structured workpieces, utilizing specific optical configurations and data transformation methods to determine feature widths and alignments across multiple layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If non-optical tools such as scanning electron microscope are used for measurement, then measurement precision is improved, but device complexity and measurement difficulty increase
Solution Approach 1:
The patent replaces complex non-optical measurement tools (scanning electron microscope) with optical reflectometry techniques. By using optical systems to measure overlay and critical dimensions, the invention achieves high measurement precision while avoiding the complexity and difficulty associated with electron microscopy equipment and procedures
Solution Approach 2:
The invention changes the measurement parameters by using optical reflection properties instead of direct electron imaging. By analyzing reflected light parameters (intensity, phase, polarization) from multi-layer structures, the system achieves precise measurements of overlay and critical dimensions through optical parameter analysis rather than mechanical/electronic scanning
2Measurement precision
If optical reflectometry is used to measure nanometer-scale features, then measurement precision is improved, but the ability to resolve small dimensions is worsened
Solution Approach 1:
The patent transitions from direct one-dimensional linear measurement to multi-dimensional measurement by analyzing reflected light in multiple dimensions (intensity, phase, polarization, wavelength). This dimensional expansion of the measurement space enables precise determination of nanometer-scale features through optical means that would otherwise be limited by diffraction constraints
Solution Approach 2:
The invention segments the measurement process into multiple optical measurements at different wavelengths, angles, or polarization states. By dividing the measurement into multiple optical probes and analyzing the combined data, the system achieves resolution of nanometer-scale features that cannot be obtained through single optical measurements
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 measurement of overlay and critical dimensions, ensuring accurate alignment and sizing of patterned layers, even at nanometer scales, thereby improving the reliability and functionality of semiconductor devices.
Implementation Method 1
measurement of parameters associated with a workpiece... by directing light onto the workpiece and measuring the light reflected from the workpiece
Implementation Method 2
The use of reflectometry techniques, including scatterometry and ellipsometry, to measure parameters such as overlay and critical dimensions by analyzing light reflected from structured workpieces
Implementation Method 3
The use of reflectometry techniques, including scatterometry and ellipsometry, to measure parameters such as overlay and critical dimensions by analyzing light reflected from structured workpieces
Data Source
AI summary
Various embodiments disclosed herein include methods for measuring a parameter associated with a workpiece. Such a method may include providing a first overlay pattern on the workpiece and a second overlay pattern over the first overlay pattern. The first overlay pattern may comprise a first plurality of features spaced apart from each other, and the second overlay pattern may comprise a second plurality of substantially optically transmissive features spaced apart from each other. The second plurality of features may be offset with respect to and partially overlapping the first plurality of features. The method may further comprise directing light onto the first and second overlay pattern such that the light is reflected from both the first and second overlay patterns and using reflectometry to obtain a measure of the parameter from the reflected light.