Pattern Inspection Apparatus Air Fluctuation Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-precision pattern inspection in semiconductor manufacturing is hindered by air fluctuation-induced displacement errors in optical imaging systems, which affect the accuracy of defect detection in ultrafine patterns, necessitating separate sensors for displacement measurement.
Innovation Solution
A pattern inspection apparatus employing a reflection illumination optical system with a semi-transmission reflection plate and time delay integration sensors to measure displacement due to air fluctuation, using reference patterns on diaphragms to calculate and correct for positional deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnifying imaging system with long focal distance lenses is used to acquire high-resolution images, then image resolution is improved, but the optical path becomes long and susceptible to air fluctuation, causing pattern image displacement
Solution Approach 1:
A reference pattern is introduced as an intermediary element in the optical path. This reference pattern serves as a mediator to measure and quantify the air fluctuation-induced displacement, enabling correction of the main pattern image position without changing the magnifying imaging system configuration
Solution Approach 2:
The system implements feedback by measuring the displacement of the reference pattern image caused by air fluctuation and using this measurement to correct the position of the main pattern image. The correction amount is determined based on the reference pattern displacement, creating a closed-loop feedback mechanism that compensates for optical path instability
2Measurement precision
If separate sensors are added to measure displacement due to air fluctuation, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The existing imaging sensor is made multi-functional by using it to capture both the main pattern image and the reference pattern image. This eliminates the need for separate displacement measurement sensors, as the same sensor performs both imaging and displacement measurement functions through appropriate optical path design
Solution Approach 2:
The measurement function for displacement is merged with the imaging function. By combining the reference pattern imaging path with the main pattern imaging path and using a single sensor for both, the system integrates multiple functions into one component, reducing overall device complexity while maintaining measurement accuracy
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 highly accurate pattern inspection by correcting for air fluctuation-induced displacements, eliminating the need for separate displacement measurement sensors and improving the precision of defect detection in semiconductor manufacturing.
Implementation Method 1
a semi-transmission reflection plate configured to reflect a portion of a reference pattern image that has passed through the first reference pattern
Implementation Method 2
air fluctuation corresponds to variation of refractive index distribution in an optical path, air fluctuation works as an effect of bending a ray of light
Implementation Method 3
air fluctuation corresponds to variation of refractive index distribution in an optical path, air fluctuation works as an effect of bending a ray of light
Data Source
AI summary
According to one aspect of the present invention, a pattern inspection apparatus includes a first diaphragm that is positioned on an optical path of a reflection illumination optical system and has a first reference pattern of a line-and-space pattern formed thereon; a semi-transmission reflection plate configured to reflect a portion of a reference pattern image that has passed through the first reference pattern; a second diaphragm which is positioned on an optical path of the imaging optical system, on which the portion of the reference pattern image reflected by the semi-transmission reflection plate is projected, and which has a second reference pattern of a line-and-space pattern formed thereon; and a first time delay integration sensor (TDI sensor) configured to receive the portion of the reference pattern image that has passed through the second reference pattern.