Rotary Anode X-Ray Source Layout for Higher Brightness and Anode Life
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Solution Overview
Problem
Existing X-Ray metrology techniques struggle to accurately characterize complex semiconductor structures due to penetration depth limitations, material opacity, and high aspect ratio features, leading to inefficient measurement processes with long integration times and reliability issues in rotary anode sources.
Innovation Solution
A high brightness, high power rotating anode X-Ray source is developed, utilizing an elongated electron beam with a specific aspect ratio and shallow take-off angle to enhance heat dissipation and brightness, enabling efficient penetration through opaque materials and high aspect ratio structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional optical radiation is used for metrology, then measurement can be performed on surface structures, but penetration depth is insufficient to characterize high aspect ratio and three dimensional structures
Solution Approach 1:
The patent changes the fundamental parameter of radiation type from optical to X-Ray, which has inherently greater penetration depth capability. This allows the measurement system to penetrate through opaque high-k materials and high aspect ratio structures that optical radiation cannot penetrate, thereby resolving the contradiction between measurement accuracy and penetration depth
Solution Approach 2:
The patent replaces optical-based measurement systems with X-Ray based systems. This substitution enables penetration through materials that are opaque to optical radiation, allowing characterization of buried structures and high aspect ratio features without requiring optical penetration
2Loss of information
If conventional optical tools with multiple angles and wavelengths are used, then measurement information is increased, but fundamental challenges with opaque materials and complex structures remain unresolved
Solution Approach 1:
The patent changes the radiation parameter from optical wavelengths to X-Ray wavelengths, which fundamentally alters the interaction with materials. X-Rays can penetrate opaque high-k materials and provide reliable measurement information for complex three dimensional structures, resolving both the information loss and reliability issues
3Power
If rotary anode X-Ray sources are used, then X-Ray generation is achieved, but heat dissipation is insufficient leading to surface degradation and limited anode lifetime
Solution Approach 1:
The patent segments the electron beam into multiple smaller beams that strike different locations on the anode surface. This segmentation distributes the heat load across multiple regions rather than concentrating it at a single point, enabling higher total beam power while maintaining anode surface temperatures within acceptable limits, thus extending anode lifetime
Solution Approach 2:
The patent transitions from a single-point electron beam impact to a distributed multi-point impact pattern on the anode surface. By utilizing the rotational motion of the anode, the system spreads heat dissipation across a larger two-dimensional area, resolving the contradiction between high power input and heat dissipation capacity
4Illumination intensity
If electron beam spot size is reduced to increase brightness, then X-Ray brightness increases, but heat concentration increases leading to faster anode degradation
Solution Approach 1:
The patent divides a single high-power electron beam into multiple lower-power beams that strike different locations on the anode. Each beam maintains sufficient intensity to generate bright X-Rays, while the distributed impact pattern prevents excessive heat concentration at any single point, resolving the contradiction between brightness and temperature
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 solution improves measurement throughput and accuracy by increasing X-Ray brightness, allowing for reliable characterization of complex semiconductor structures with reduced surface degradation and extended anode lifetime.
Implementation Method 1
A stream of electrons having a landing energy of at least 80 keV and beam power of at least 400 Watts is directed to a rotating anode material structure
Implementation Method 2
The stream of electrons is incident to the rotating anode material structure at a take-off angle of more than three degrees from normal incidence
Implementation Method 3
The spatial distribution of the electron intensity of the stream of electrons at the location of incidence is elongated in shape
Implementation Method 4
high brightness, high power rotating anode X-Ray source is developed, utilizing an elongated electron beam with a specific aspect ratio and shallow take-off angle to enhance heat dissipation
Data Source
AI summary
PROBLEM TO BE SOLVED: To provide a rotary anode X-ray tube capable of achieving a long product life, or capable of increasing thermal input to an anode target. SOLUTION: A rotary anode X-ray tube 1 includes a cathode 60, an anode target 50, a fixed shaft 10, a rotating body 20, and a liquid metal LM. The fixed shaft 10 has a first radial bearing surface S10a and a second radial bearing surface S10b. The rotating body 20 has a third radial bearing surface S21a, a fourth radial bearing surface S21b, and a heat transmission region 21a to which the anode target 50 is fixed and the heat of which is transmitted. In a direction along the central axis A, the center of the heat transmission region 21a is located between a first dynamic bearing B1 and a second dynamic bearing B2.