Semiconductor X-Ray Inspection Using Multilayer KB Mirrors
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Solution Overview
Problem
Conventional optical and X-ray inspection methods struggle to non-destructively inspect fine structures within semiconductors, particularly those with deep, complex structures, due to limitations in resolution and efficiency when using high-energy X-rays, and existing X-ray microscopes face challenges in achieving high-resolution imaging in a laboratory setting.
Innovation Solution
A semiconductor inspection apparatus utilizing a high-output X-ray source with a condenser mirror and a reflecting mirror type X-ray lens unit, both featuring multilayer films for high reflectivity, allows for high-resolution imaging by increasing the numerical aperture and capturing high-energy X-rays at large angles, enabling non-destructive inspection of microstructures within semiconductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a Fresnel zone plate lens (FZP) is used for high-energy X-rays, then the imaging system can be compact, but the diffraction efficiency is significantly reduced and numerical aperture is very small
Solution Approach 1:
The patent changes the fundamental parameter of the optical element from a Fresnel zone plate lens to a Kirkpatrick-Baez mirror system. This parameter change enables the use of reflection instead of diffraction, achieving both high efficiency and large numerical aperture with high-energy X-rays
Solution Approach 2:
The patent replaces the diffractive optical system (FZP) with a reflective optical system (KB mirror). This substitution eliminates the efficiency limitations of diffraction-based systems while enabling larger numerical aperture through the geometric optics approach
2Loss of energy
If the total reflection of X-rays is used in KB mirror, then the reflectivity is high, but the angle of incidence must be limited below the critical angle requiring increased length in X-ray beam direction
Solution Approach 1:
The patent uses a composite optical system combining two KB mirrors with different orientations (one for horizontal focusing, one for vertical focusing). This composite approach enables large angle of incidence while maintaining high reflectivity and achieving compact overall length
Solution Approach 2:
The patent separates the focusing functions into two dimensions using two mirrors oriented perpendicular to each other. This dimensional separation allows each mirror to operate at optimal angles while achieving compact system length in the beam direction
3Measurement precision
If conventional optical inspection methods are used, then the inspection process is simple, but fine structures in deep semiconductor structures cannot be inspected
Solution Approach 1:
The patent employs periodic scanning motion of the X-ray beam across the semiconductor sample using galvanometer mirrors. This periodic scanning action enables high-resolution inspection of deep structures while maintaining a relatively simple overall system configuration
Solution Approach 2:
The patent introduces an X-ray optical system as an intermediary between the X-ray source and the semiconductor sample. This intermediary enables high-resolution imaging of deep structures without requiring complex sample preparation or destructive methods
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
The apparatus achieves high-resolution, non-destructive imaging of semiconductor microstructures, allowing for the inspection of structures down to 50 nm and enabling the evaluation of internal structures without destructive methods, improving manufacturing productivity and enabling laboratory-based inspection.
Implementation Method 1
each mirror constituting the condenser mirror and the reflecting mirror type X-ray lens unit has a reflective surface that is formed of a multilayer film having a high reflectivity for X-rays with a specific wavelength
Implementation Method 2
an X-ray irradiation unit having a condenser mirror for condensing and irradiating emitted X-rays toward a sample of semiconductor
Implementation Method 3
a reflecting mirror type X-ray lens unit for forming an image with an X-ray transmitted through the sample
Data Source
AI summary
A semiconductor inspection apparatus, semiconductor inspection system, and semiconductor inspection method capable of locally inspecting a microstructure inside a semiconductor by obtaining an enlarged image with sufficient intensity with a size that can be stored in a laboratory are provided. A semiconductor inspection apparatus using an enlarged X-ray image comprises an X-ray source having a micro focus and high output, an X-ray irradiation unit having a condenser mirror for condensing and irradiating emitted X-rays toward a sample of semiconductor, a sample holder for holding the sample, a reflecting mirror type X-ray lens unit for forming an image with an X-ray transmitted through the sample and an imaging unit for acquiring the formed X-ray image, and each mirror constituting the condenser mirror and the reflecting mirror type X-ray lens unit has a reflective surface that is formed of a multilayer film having a high reflectivity for X-rays with a specific wavelength.