Inspection Apparatus Weighted Summation Brightness Analysis
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Solution Overview
Problem
Existing macro inspection apparatuses face challenges in accurately inspecting semiconductor wafers due to brightness value changes influenced by pattern, film-thickness, and optical system shading, leading to errors in CD value association.
Innovation Solution
An inspection apparatus and method that utilize a processing device to perform inspections based on a correlation between brightness values and pattern sizes, employing multiple regression analysis and weighted summation of images taken under various shooting conditions to isolate and accurately measure CD values, film thickness, and surface profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a macro inspection apparatus takes an image of a wafer at low magnification to inspect the whole wafer in a short time, then productivity is improved, but measurement precision deteriorates due to brightness value changes influenced by pattern, film-thickness, and optical system shading
Solution Approach 1:
The patent segments the inspection process by capturing multiple images under different shooting conditions (different illumination angles, polarization states, or wavelengths) and processing them separately through weighted summation. This allows the system to maintain low magnification for high productivity while compensating for shading and film-thickness effects through multi-condition imaging and statistical processing, thereby improving measurement precision without sacrificing inspection speed
Solution Approach 2:
The patent changes shooting condition parameters (illumination angle, polarization, wavelength) to capture images under multiple conditions. By varying these parameters and applying weighted summation with statistically determined weights, the system compensates for brightness value changes caused by film-thickness and optical shading, improving CD measurement accuracy while maintaining the high productivity benefits of macro low-magnification inspection
2Device complexity
If brightness values are directly associated with CD values for inspection, then device complexity is reduced, but measurement precision deteriorates due to interference from film-thickness and optical system shading
Solution Approach 1:
The patent introduces an intermediary processing step that uses statistical techniques (such as multiple regression analysis) to determine weighted summation parameters based on reference measurements. This intermediary layer processes the raw brightness values from multiple shooting conditions to eliminate the influence of film-thickness and shading effects before associating with CD values, thereby improving measurement precision while adding minimal complexity through software-based statistical processing
Solution Approach 2:
The patent performs preliminary measurements on reference samples with known CD values to statistically determine the optimal weighting parameters for combining images from different shooting conditions. This preliminary action establishes the weighted summation parameters that will be used in subsequent inspections, enabling the system to compensate for film-thickness and shading effects without requiring complex real-time adjustments during actual inspection
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 enables highly accurate inspections by reducing errors and effectively extracting relevant information, allowing for precise measurements of CD values, film thickness, and surface profiles with improved productivity.
Implementation Method 1
a light source that illuminates a sample on which a pattern is formed; a detector that detects light reflected from the sample illuminated by the light source
Data Source
AI summary
An inspection apparatus and an inspection method capable of performing an inspection more accurately are provided. An inspection apparatus according to the present invention includes a light source 10 that illuminates a sample 30 in which a pattern is formed, a detector 11 that detects light reflected from the sample 30 illuminated by the light source, and a processing device 50 that performs an inspection based on a correlation between a brightness value of a sample image obtained by the detector and a size in a surface shape or a size in a width direction of the pattern of the sample 30. The processing device 50 performs the inspection based on a summation value obtained by adding up brightness values of sample images with weights, the sample images being obtained under a plurality of shooting conditions.