Magnetic Element Structure for Precise Eddy Current End-Point Sensing
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Solution Overview
Problem
The challenge in semiconductor wafer polishing is ensuring optimal polishing end-point detection, as existing techniques struggle to accurately differentiate between copper wiring and planar metal distributions, leading to insufficient or excessive polishing, which affects circuit integrity and performance.
Innovation Solution
A magnetic element configuration with a bottom magnetic body, central and peripheral magnetic bodies, internal and external coils, and detection coils is employed to enhance the magnetic field strength and precision in eddy current sensing, allowing for better differentiation and end-point detection during polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional pod-shaped coil eddy current sensor is used, then the device complexity is low, but the magnetic field strength is insufficient for detecting fine wiring patterns
Solution Approach 1:
The magnetic element is divided into multiple magnetic bodies (first, second, third, and fourth magnetic bodies) arranged in a segmented configuration. Each magnetic body is associated with specific coils (internal and external coils) that generate magnetic fields in different regions. This segmentation allows the magnetic field to be distributed and optimized across different areas of the semiconductor wafer, enabling detection of both fine wiring patterns and planar metal distributions while managing overall device complexity through modular structure.
Solution Approach 2:
The invention transitions from a conventional single-plane pod-shaped coil to a three-dimensional magnetic element structure with magnetic bodies arranged in multiple layers and positions. The internal coils are disposed within cavities of magnetic bodies, while external coils are positioned on the outer periphery, creating a multi-dimensional magnetic field distribution that enhances field strength and detection capability without simply scaling up the conventional two-dimensional coil design.
2Measurement precision
If the magnetic field strength is increased to detect fine wiring, then the detection precision improves, but the device complexity increases due to additional coils and magnetic bodies
Solution Approach 1:
The magnetic element structure employs a nested configuration where internal coils are disposed within cavities formed by the magnetic bodies. The first and second magnetic bodies have cavities that accommodate internal coils, which are nested within the magnetic structure. External coils are positioned on the outer periphery, creating a nested arrangement of coils within magnetic bodies that maximizes magnetic field generation while optimizing space utilization and managing structural complexity.
Solution Approach 2:
The invention merges multiple functional components into an integrated magnetic element structure. Multiple magnetic bodies (first, second, third, fourth) are combined with internal and external coils to form a unified detection system. The magnetic bodies are arranged to work together, with some having cavities for internal coils and others providing external coil mounting, creating a combined structure that achieves enhanced detection precision through coordinated operation of all components.
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 configuration increases the magnetic field strength and precision, enabling accurate detection of polishing end-points and preventing circuit damage from over- or under-polishing, thus ensuring optimal circuit integrity and performance.
Implementation Method 1
an internal coil disposed on an outer periphery of the central magnetic body and capable of generating a magnetic field and an external coil disposed on an outer periphery of the peripheral magnetic body and capable of generating a magnetic field
Implementation Method 2
the density of eddy current flowing through the object needs to be greater
Data Source
AI summary
A magnetic element for strengthening a magnetic field formed in an object and an eddy current sensor using the magnetic field are provided. The eddy current sensor includes a bottom face portion which is a magnetic body, a magnetic core portion provided at the middle of the bottom face portion and a peripheral wall portion provided on the periphery of the bottom face portion. The eddy current sensor further includes an excitation coil disposed on an outer periphery of the magnetic core portion and capable of generating a magnetic field and an excitation coil disposed on an outer periphery of the peripheral wall portion and capable of generating a magnetic field.