Metrology Apparatus for Semiconductor Pattern Measurement
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Solution Overview
Problem
As semiconductor integrated circuits become increasingly complex with narrower pitches and higher aspect ratios, existing optical measurement methods struggle to accurately measure patterns with pitches less than the wavelength of the light source, leading to difficulties in detecting fabrication failures and preventing pattern failures.
Innovation Solution
A metrology method and apparatus that utilize polarized light, a beam splitter, a polarizer, a wavelength plate, and a detector to generate and analyze interference signals between pattern reflection light and phase-controlled mirror reflection light, allowing for precise measurement of patterns with pitches less than the light wavelength by controlling polarization characteristics and phase delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical measurement methods are used, then measurement simplicity is maintained, but measurement precision deteriorates for patterns with pitch less than light wavelength
Solution Approach 1:
The patent segments the optical measurement process into multiple distinct functional components: light source, polarizer, beam splitter, phase shifter, objective lens, detector, and image processor. Each component performs a specific function in the interference-based measurement chain, enabling precise measurement of sub-wavelength patterns while maintaining systematic control over the complex measurement process
Solution Approach 2:
The patent introduces several intermediary elements to bridge the gap between conventional optical measurement and sub-wavelength precision: polarizer (mediates light polarization), beam splitter (mediates light path division), phase shifter (mediates phase difference control), and interference pattern mediator (the object itself which modulates the interference pattern). These intermediaries enable precise measurement without requiring direct sub-wavelength resolution
2Measurement precision
If optical measurement methods are used for highly integrated circuits, then productivity is maintained, but measurement precision deteriorates due to narrow pitch and high aspect ratio
Solution Approach 1:
The patent changes key optical parameters to achieve sub-wavelength measurement precision: it controls light wavelength (using specific wavelength sources), polarization state (using polarizers and wave plates), and phase difference (using phase shifters). By systematically varying these parameters, the system achieves high precision measurement of narrow pitch and high aspect ratio patterns while maintaining measurement throughput through automated parameter control
3Measurement precision
If polarized light and interference methods are used, then measurement precision for sub-wavelength patterns is improved, but device complexity increases
Solution Approach 1:
The patent designs the measurement system with universal, multi-functional components that can handle various measurement scenarios: the beam splitter serves both to divide and recombine light paths; the phase shifter adjusts phase for different measurement modes; the polarizer and wave plates work together in multiple polarization configurations. This multi-functionality reduces the need for multiple specialized components, managing device complexity while maintaining high measurement precision for sub-wavelength patterns
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 reliable analysis of semiconductor patterns with ultra-fine features, improving pattern inspection accuracy and preventing fabrication failures, thus enhancing semiconductor device yields.
Implementation Method 1
a first polarizer suitable for generating a polarized light by polarizing the emitted light
Implementation Method 2
a beam splitter suitable for dividing the polarized light into a first divided light and a second divided light
Implementation Method 3
a second polarizer suitable for generating a pattern reflection light by polarizing the first divided light and irradiating the polarized first divided light to an object
Implementation Method 4
a wavelength plate suitable for controlling a phase of the mirror reflection light
Implementation Method 5
a detector suitable for changing a polarization characteristic of an interference signal between the pattern reflection light and the mirror reflection light
Data Source
AI summary
A metrology method includes obtaining a pattern reflection light reflected from an object by irradiating a first divided light, which is generated by reflecting a polarized light, to the object; obtaining a phase-controlled mirror reflection light reflected from a reflector by irradiating a second divided light, which is generated by transmitting the polarized light, to the reflector; and obtaining a pattern of the object based on an interference signal between the pattern reflection light and the mirror reflection light.