Coordinate Measuring Machine Structured Illumination Adaptation
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Solution Overview
Problem
Current coordinate measuring machines for semiconductor wafers use homogeneously illuminated pupils of fixed size and unpolarized light, which fail to accurately determine the position and dimension of structures under structured illumination, leading to increased contrast requirements and measurement errors due to systematic errors from varying illumination types and polarizations.
Innovation Solution
A coordinate measuring machine equipped with adjustable optical elements that manipulate the size, type, and polarization of illumination to match the structured illumination used in stepper processes, allowing for incident and transmitted light illumination paths with optical elements positioned in specific locations to replicate the illumination conditions of the stepper process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If homogeneously illuminated pupil of fixed size is used, then device complexity is reduced, but measurement precision deteriorates due to inability to match stepper illumination conditions
Solution Approach 1:
The patent implements dynamically adjustable optical elements including variable aperture iris diaphragms and polarization control mechanisms that allow the illumination system to adapt its parameters (aperture size, polarization state) to match different stepper illumination conditions, transforming a static fixed-illumination system into a dynamic configurable one
Solution Approach 2:
The system changes physical parameters of the illumination light including aperture numerical aperture (NA), polarization orientation (linear, circular, elliptical), and illumination angle to replicate the specific illumination conditions used in semiconductor steppers, thereby improving measurement accuracy without permanently increasing system complexity
2Ease of operation
If unpolarized light is used, then ease of operation is improved, but measurement precision deteriorates due to systematic errors from polarization mismatch
Solution Approach 1:
The patent introduces polarization control as an adjustable parameter, allowing the operator to select between unpolarized, linearly polarized, circularly polarized, or elliptically polarized light depending on the specific measurement requirements and stepper process conditions, thereby eliminating systematic errors while maintaining operational flexibility
3Device complexity
If fixed pupil size is used, then device complexity is reduced, but adaptability deteriorates due to inability to adjust to different illumination conditions
Solution Approach 1:
The patent employs dynamically controllable optical elements including variable aperture mechanisms and polarization controllers that enable the system to adapt to different illumination conditions (dipole, quadrupole, annular, etc.) without requiring multiple fixed configurations, achieving versatility through controlled dynamic adjustment rather than static multiplicity
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 accurate measurement of structure positions and dimensions on substrates by adapting the illumination to match stepper conditions, reducing systematic measurement errors and improving contrast and coherence, thus enhancing measurement precision and quality.
Implementation Method 1
manipulating the size and/or the type and/or the polarization of the illumination of a pupil such that the structured illumination of the substrate in the coordinate measuring machine corresponds to the structured illumination of the same substrate in the exposure process with a stepper
Data Source
AI summary
A coordinate measuring machine for the structured illumination of substrates is disclosed. The incident light illumination means and/or the transmitted light illumination means have a pupil access via which at least one optical element is positionable in the optical illumination path. The size and/or type and/or the polarization of the pupil illumination may be manipulated such that the structured illumination of the substrate in the coordinate measuring machine corresponds to the structured illumination of this substrate in the exposure process with a stepper.