Mask Pattern Inspection Focus Alignment Across Multiple Sensors
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Solution Overview
Problem
Existing pattern inspection apparatuses face challenges in accurately adjusting the focal position due to shallow focal depth and fluctuations in the inspection optical system, leading to inconsistent focus adjustment across different regions on the mask, which affects the detection of ultrafine pattern defects in semiconductor manufacturing.
Innovation Solution
The apparatus employs a common detection optical system to illuminate and guide light fluxes from multiple regions of the substrate to a common optical path, using separate sensors and detection mechanisms to detect and adjust positional relationships between focal positions, allowing for simultaneous focus adjustment across different imaging sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a common detection optical system is used to guide multiple light fluxes to a common optical path, then focus adjustment consistency across different regions is improved, but device complexity increases due to additional light flux separation mechanisms
Solution Approach 1:
The patent segments the optical system into distinct functional modules: a common detection optical system for guiding multiple light fluxes, and separate light flux separation mechanisms for each flux. This segmentation allows independent optimization of each component while maintaining overall system consistency, resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The common detection optical system serves multiple functions by guiding light fluxes from different regions (first, second, and third light fluxes) through a single optical path to a common detection point. This multi-functionality improves focus adjustment consistency across all regions while avoiding the need for separate detection systems, thereby managing device complexity.
2Measurement precision
If separate detection mechanisms are used for each light flux, then detection accuracy for each region is improved, but processing time increases due to sequential analysis requirements
Solution Approach 1:
The patent merges multiple detection results by guiding all light fluxes to a common detection point where they are analyzed simultaneously. The control mechanism integrates information from all regions in a unified processing flow, achieving high detection accuracy while minimizing processing time through parallel rather than sequential analysis.
Solution Approach 2:
The common optical path acts as an intermediary that receives and harmonizes multiple light fluxes before detection. This intermediary structure enables synchronized processing of all regional data, maintaining high detection accuracy while avoiding the time loss associated with sequential processing of separate detection mechanisms.
3Adaptability or versatility
If the focal depth is increased to accommodate larger focal ranges, then the ability to capture images across different mask regions is improved, but the detection precision for ultrafine pattern defects deteriorates
Solution Approach 1:
The patent resolves the focal depth contradiction by transitioning from a single-dimension focus adjustment to a multi-dimensional solution: multiple light fluxes from different spatial regions are guided to a common detection point. This allows each flux to maintain its optimal focal depth for ultrafine defect detection while the system collectively covers the entire mask area through coordinated multi-region imaging.
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 ensures accurate and consistent focus adjustment across multiple imaging sensors, enhancing the detection of pattern defects on semiconductor masks, thereby improving the yield and precision in semiconductor manufacturing.
Implementation Method 1
a first sensor configured to capture a first optical image of the substrate by receiving a first light flux transmitted through or reflected on a first region of the substrate
Implementation Method 2
a second sensor configured to capture a second optical image of the substrate by receiving a second light flux transmitted through or reflected on a second region of the substrate
Implementation Method 3
a common detection optical system configured to illuminate a third region of the substrate with light for focus adjustment and guide the first light flux, the second light flux, and a third light flux reflected on the third region of the substrate to a common optical path of a detection system
Data Source
AI summary
According to one aspect of the present invention, a pattern inspection apparatus includes: a first detection mechanism configured to detect a change in a first positional relationship between a focal position of a first light flux and a first sensor; a second detection mechanism configured to detect a change in a second positional relationship between a focal position of a second light flux and a second sensor; a third detection mechanism configured to detect a change in a third positional relationship between a focal position of a separated third light flux and a focal position of a common detection optical system on a substrate side; and a control circuit configured to control at least two of the first adjustment mechanism, the second adjustment mechanism, and the third adjustment mechanism so as to adjust at least two of the first positional relationship, the second positional relationship, and the third positional relationship.