Lithography Apparatus Foreign Substance Detection via Contrast Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing lithography apparatuses require excessive time to detect abnormal holding of originals due to foreign substances, which affects alignment accuracy in semiconductor and display manufacturing.
Innovation Solution
A lithography apparatus with a measuring unit that uses focus position and contrast analysis to quickly determine if an original is abnormally held by comparing the contrasts of original and reference marks, allowing for rapid detection of misalignment caused by foreign substances or other abnormalities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If height measurement is performed by repeatedly changing focal length of measuring unit, then foreign substance detection accuracy is improved, but measurement time increases significantly
Solution Approach 1:
The invention extracts the height measurement function from the original stage and implements it on the substrate stage. The measuring unit measures the substrate surface height at multiple positions to calculate substrate surface unevenness, which indirectly provides information about foreign substances between the original and original stage without requiring direct measurement of the original itself.
Solution Approach 2:
The substrate surface height serves as an intermediary measurement. By measuring the substrate surface at multiple positions and calculating unevenness, the system indirectly detects the presence of foreign substances between the original and original stage, avoiding the time-consuming direct focal length scanning of the original.
2Manufacturing precision
If alignment accuracy is improved by detecting foreign substances, then pattern transfer precision is improved, but detection complexity increases
Solution Approach 1:
The measuring unit that already exists in the lithography apparatus is utilized for the additional function of detecting foreign substances. The same measuring unit used for substrate surface measurement is repurposed to measure substrate surface height at multiple positions for foreign substance detection, eliminating the need for separate detection hardware.
Solution Approach 2:
The measuring unit is designed to perform multiple functions: substrate surface measurement for focus control and foreign substance detection through multi-position height measurement. This multi-functionality reduces the need for additional specialized detection equipment while maintaining alignment 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 faster detection of abnormal holding conditions, reducing the time required to determine misalignment and preventing pattern misalignment during the manufacturing process.
Implementation Method 1
a measuring unit configured to measure a mark provided on the substrate and obtain first focus position information indicating a focus position at which the measured mark is in a focused state
Implementation Method 2
obtain first contrast information indicating a contrast of an image of the measured mark
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
Provided is a lithography apparatus capable of detecting the abnormal holding of an original in a shorter period of time. The lithography apparatus is configured to form a pattern on a substrate through use of the original, and includes: a holding unit configured to hold the original on which a first mark is formed; a measuring unit configured to pick up an image of the first mark; and a control unit configured to: cause the measuring unit to obtain the image of the first mark on the original held by the holding unit with a focus position of the measuring unit being adjusted to a reference position; and determine that the original is being abnormally held by the holding unit when a change in a first contrast, which is a contrast of the image of the first mark with respect to a reference contrast, falls out of an allowable range.