Semiconductor Substrate Scattered-Light Evaluation of Subsurface Damage
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Solution Overview
Problem
Conventional methods for evaluating subsurface damaged layers in semiconductor substrates are destructive, making it difficult to assess the distribution of strain across the surface and reducing manufacturing throughput, especially for challenging materials like silicon carbide.
Innovation Solution
A non-destructive method using laser light with penetration characteristics to measure the intensity of scattered light from the subsurface damaged layer, allowing for the calculation of strain distribution across the semiconductor substrate's surface without destroying it.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If destructive inspection methods (TEM, SEM, EBSD) are used to evaluate subsurface damaged layers, then measurement precision is improved, but the semiconductor substrate cannot be returned to the manufacturing process and productivity is reduced
Solution Approach 1:
The patent replaces mechanical destructive inspection methods (TEM, SEM, EBSD requiring physical sectioning) with optical measurement using laser light and scattered light detection. This substitution enables non-contact, non-destructive evaluation of subsurface damaged layers, allowing substrates to remain in the manufacturing process while maintaining measurement capability.
Solution Approach 2:
The patent introduces scattered light intensity as an intermediary parameter to indirectly evaluate subsurface damaged layers. By measuring the intensity of laser light scattered by subsurface defects rather than directly imaging them, the system achieves non-destructive evaluation while maintaining measurement precision.
2Measurement precision
If Raman spectroscopy is used to evaluate subsurface damaged layers, then non-destructive evaluation is achieved, but measurement time increases significantly reducing productivity
Solution Approach 1:
The patent changes the measurement parameter from Raman scattering intensity (which requires long integration times) to general scattered light intensity in the visible range. This parameter change enables much faster detection while still providing information about subsurface damaged layers through the relationship between scattered light intensity and strain distribution.
Solution Approach 2:
The patent employs rapid scanning of laser beams across the substrate surface in periodic sequences, enabling fast coverage of large areas. This periodic scanning approach dramatically reduces total measurement time compared to point-by-point Raman spectroscopy while maintaining evaluation capability.
3Measurement precision
If local evaluation methods are used for subsurface damaged layers, then measurement precision at specific points is improved, but the ability to evaluate distribution over wide range is reduced
Solution Approach 1:
The patent divides the substrate surface into multiple measurement regions and systematically scans the laser beam across these segments. By combining data from all segments, the system achieves both local measurement precision and comprehensive wide-area distribution evaluation of subsurface damaged layers.
Solution Approach 2:
The patent transitions from two-dimensional surface evaluation to three-dimensional subsurface evaluation by utilizing the depth penetration of laser light and analyzing scattered light intensity variations. This enables evaluation of subsurface damaged layers at different depths while maintaining spatial distribution information across the entire substrate surface.
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 rapid and accurate evaluation of subsurface damaged layers, improving manufacturing efficiency by allowing semiconductor substrates to be reused in the manufacturing process without destruction.
Implementation Method 1
causing laser light having penetration characteristics to be incident from a surface of a semiconductor substrate having a subsurface damaged layer under the surface and measuring an intensity of scattered light scattered under the surface
Data Source
AI summary
An object of the present invention is to provide a novel technology capable of evaluating a subsurface damaged layer without destroying a semiconductor substrate. As means for solving this object, the present invention includes a measurement step of causing laser light having penetration characteristics to be incident from a surface of a semiconductor substrate having a subsurface damaged layer under the surface and measuring an intensity of scattered light scattered under the surface, and an evaluation step of evaluating the subsurface damaged layer on the basis of the intensity of the scattered light obtained in the measurement step.