Photomask Pattern Characteristic Detection for Transmittance and Line-Width Analysis
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Solution Overview
Problem
Conventional photomask testing apparatuses are limited in detecting transmittance and line-width distributions across the entire area of photomasks with high resolution, failing to identify the cause of process margin or yield reduction due to subtle anomalies not classified as defects.
Innovation Solution
A characteristic-detection apparatus and method that create detection data from optical images of photomasks, extract pattern characteristics and positional information, and perform inverse-transformation operations to calculate wafer plane patterns, allowing for high-resolution detection of transmittance and line-width profiles across the entire photomask area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional photomask testing apparatuses use limited detection techniques, then device complexity is reduced, but measurement precision and detection sensitivity deteriorate
Solution Approach 1:
The apparatus segments the photomask detection process into multiple specialized components: an optical system for image formation, a CCD sensor for light detection, and a computer for data processing and analysis. This segmentation allows each component to be optimized for its specific function, achieving high detection sensitivity without requiring a monolithic complex device.
Solution Approach 2:
The patent introduces an optical system as an intermediary between the photomask and the CCD sensor. This optical system forms enlarged optical images of the photomask patterns, enabling the CCD sensor to detect subtle variations in transmittance and line-width with high precision. The intermediary optical system bridges the gap between the microscopic photomask features and the detection capabilities of the sensor.
2Area of stationary object
If conventional techniques detect only at predetermined intervals, then detection area coverage is limited, but productivity is improved
Solution Approach 1:
The apparatus enables continuous detection across the entire photomask area by capturing optical images of the complete photomask pattern. The computer processes the entire image data set to calculate transmittance and line-width at all positions simultaneously, providing continuous coverage rather than discrete interval sampling. This continuous action maintains high productivity while achieving complete area coverage.
Solution Approach 2:
The optical system creates an enlarged dimensional representation of the photomask patterns, projecting microscopic two-dimensional patterns into enlarged images that can be captured comprehensively. This dimensional transformation allows the entire photomask area to be detected in a single measurement, converting a potentially time-consuming point-by-point inspection into a comprehensive area-wide detection.
3Manufacturing precision
If conventional apparatuses cannot detect subtle anomalies, then manufacturing precision evaluation is insufficient, but loss of information is reduced
Solution Approach 1:
The computer analyzes the detected transmittance and line-width data to identify subtle anomalies that deviate from expected patterns. This feedback mechanism allows the system to detect and report manufacturing precision issues that would be imperceptible through conventional inspection methods, providing comprehensive information about photomask quality without losing subtle defect information.
Solution Approach 2:
The patent replaces mechanical or manual inspection methods with an optical-mechanical system combined with digital image processing. The optical system captures precise transmittance information, and the computer performs automated analysis to detect subtle anomalies. This substitution of mechanical inspection with optical-digital methods enables detection of fine manufacturing variations while preserving information about subtle defects.
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 precise evaluation of photomask quality and identification of subtle anomalies affecting process margin and yield, improving detection sensitivity and resolution beyond conventional techniques.
Implementation Method 1
detecting portion to detect pattern characteristics of the target pattern for the pattern characteristic detection within the area where the pattern characteristics are to be detected by converting light intensity of an optical image formed on a CCD image sensor into electric digital signal
Data Source
AI summary
According to one embodiment, a pattern characteristic detection apparatus for a photomask includes a detection-data creating portion, a reference-data creating portion, an extracting portion, a first area-setting portion, a detecting portion and an collecting portion. The detection-data creating portion is configured to create detection data on the basis of an optical image of a pattern formed on a photomask. The reference-data creating portion is configured to create reference data of the pattern. The extracting portion is configured to extract a pattern for pattern characteristic detection and positional information of the extracted pattern. The first area-setting portion is configured to set an area where pattern characteristics are to be detected, and configured to extract a target pattern. The detecting portion is configured to detect pattern characteristics of the target pattern within the area. In addition, the collecting portion is configured to collect the detected pattern characteristics.