Laser Reflection Detection for Semiconductor Surface Defects
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Solution Overview
Problem
Current methods for detecting crystal defects on semiconductor substrates, such as visual inspection and X-ray topography, are inefficient and inaccurate, particularly in distinguishing surface and internal defects, and fail to selectively quantify slip dislocations.
Innovation Solution
A detection device that emits laser light to a substrate's surface, calculates the inclination based on the reflection angles at flat and inclined surfaces, and uses a quadrant photodiode to detect defects, allowing for precise identification of surface defects like slip dislocations without damaging the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visual inspection is used to quantify slip dislocations, then the measurement can be performed, but significant time and labor are required and test results vary due to human visual perception
Solution Approach 1:
The patent replaces the mechanical visual inspection system with an optical measurement system using laser light and photodetectors. The laser beam scans the substrate surface and detects slip dislocations through optical scattering, eliminating human visual perception and manual measurement, thereby achieving automated, precise, and efficient quantification of crystal defects.
Solution Approach 2:
The patent changes the measurement parameter from human visual perception to optical scattering intensity detection. By using a photodetector to measure the intensity of light scattered by slip dislocations, the system transforms the detection mechanism into a quantitative optical measurement that is both precise and automated, resolving the contradiction between accuracy and time consumption.
2Adaptability or versatility
If X-ray topography method is used to evaluate crystal defects, then defects on surface and interior can be observed, but it is difficult to distinguish between surface defects and internal defects
Solution Approach 1:
The patent extracts the surface defect detection function from the general X-ray topography method by using laser light scattering specifically sensitive to surface slip dislocations. This selective extraction allows the system to focus on surface defects while being aware of internal defects, achieving precise discrimination between surface and internal defect locations.
Solution Approach 2:
The patent introduces laser light scattering as an intermediary measurement mechanism between the substrate and the detection system. The laser light interacts differently with surface slip dislocations compared to internal defects, creating a mediating effect that enables differentiation and precise location discrimination of defects at different depths.
3Reliability
If laser light scattering method is used to detect crystal defects, then mechanical detection variations are reduced, but specific crystal defects such as slip dislocation cannot be selectively quantified
Solution Approach 1:
The patent applies local quality by analyzing the specific characteristics of light scattering at different locations and angles. By examining the angular distribution and intensity patterns of scattered light, the system can identify the unique scattering signature of slip dislocations, achieving selective quantification while maintaining reliable and consistent measurements.
Solution Approach 2:
The patent uses a scanning laser beam that dynamically moves across the substrate surface, allowing real-time detection and classification of defects. The dynamic scanning approach enables the system to collect spatially-resolved scattering data, which provides both measurement consistency through repeated scans and defect type selectivity through pattern recognition.
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 method enables accurate and non-destructive detection of surface defects on semiconductor substrates, improving the quality assessment of semiconductor devices by reducing human error and enhancing the ability to distinguish between surface and internal defects.
Implementation Method 1
light resulting from the laser light reflected at the surface
Implementation Method 2
a light-detecting portion on which light resulting from the laser light reflected at the surface is incident, and that detects a first position at which the light is incident
Data Source
AI summary
A detection device 1 includes an irradiator 3, a photodiode 4, and an evaluation portion 5. The irradiator 3 emits laser light to a surface of a substrate W. The light resulting from the laser light reflected at the surface of the substrate W is incident on the photodiode 4, and the photodiode 4 detects a first position P1 at which the light is incident. The evaluation portion 5 includes a calculation portion and a detection portion. The calculation portion calculates an inclination of the surface of the substrate W on the basis of the first position P1 and a second position P2 at which light is incident on the photodiode 4 when the laser light is reflected at the surface of the substrate W that is flat. The detection portion detects a defect formed on the surface of the substrate W on the basis of the inclination.