Eddy Current Sensor Single-Row Multi-Layer Coil for CMP
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Solution Overview
Problem
Conventional CMP processes for semiconductor wafers face challenges in efficiently detecting and removing thin metal films during polishing, leading to increased inspection and processing times due to the need for separate inspection and repolishing steps, which can result in reduced throughput and potential short circuits or increased resistance in circuits.
Innovation Solution
An eddy current sensor with a detection coil formed by winding a wire or conductive material in a single row and plural layers, allowing for closer proximity to the substrate and improved sensitivity without increasing oscillation frequency, amplification degree, or exciting voltage, enabling real-time detection and removal of thin metal films during polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional eddy current sensors with multi-row coil windings are used, then the sensor can detect metal films, but the sensor cannot be positioned close to the substrate due to insulation requirements, reducing detection sensitivity
Solution Approach 1:
The coil winding is segmented into a single row with multiple layers instead of multiple rows. This segmentation allows the sensor to be positioned closer to the substrate while maintaining adequate insulation, as the layered structure provides sufficient electrical isolation within a compact vertical arrangement, thereby improving detection sensitivity without requiring complex multi-row configurations
Solution Approach 2:
The coil structure transitions from a horizontal multi-row arrangement to a vertical multi-layer arrangement. This dimensional change allows the sensor to approach the substrate more closely in the vertical dimension while the layered structure provides the necessary insulation in the horizontal plane, effectively resolving the contradiction between proximity and insulation requirements
2Reliability
If separate inspection and repolishing steps are performed after CMP processing, then metal film removal can be verified, but processing time increases and throughput decreases
Solution Approach 1:
The eddy current sensor enables continuous monitoring of metal film thickness during the CMP polishing process itself, eliminating the need for separate inspection steps. The sensor continuously detects metal film presence and provides real-time feedback to the control system, allowing the polishing process to proceed uninterrupted and be terminated precisely when the metal film is fully removed, thereby maintaining reliability while eliminating time losses
Solution Approach 2:
The sensor output is fed back to the control system in real-time during polishing, enabling dynamic adjustment of the polishing process. When the metal film is detected to be fully removed based on the sensor signal, the control system automatically terminates the polishing process, eliminating the need for separate inspection and repolishing steps and significantly reducing processing time while ensuring reliable metal film removal
3Reliability
If insufficient polishing is performed to leave copper layer on insulating layer, then circuits may short-circuit, but excessive polishing removes copper layer and increases circuit resistance
Solution Approach 1:
The eddy current sensor provides real-time feedback on metal film thickness during polishing, enabling the control system to precisely control the polishing process. The sensor detects the metal film presence and thickness continuously, allowing the system to terminate polishing at the exact moment when the metal film is fully removed, thereby preventing both insufficient polishing (which would cause short circuits) and excessive polishing (which would remove the metal film and increase resistance), achieving precise manufacturing control
Solution Approach 2:
The eddy current sensor is positioned to detect the metal film before and during the polishing process, allowing the system to anticipate when the metal film will be fully removed. This preliminary detection capability enables the control system to prepare for and execute the precise termination of polishing at the optimal moment, preventing both under-polishing and over-polishing and ensuring circuit functionality with precise thickness control
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 solution enhances sensor sensitivity, allows for stable detection of thin films, reduces inspection and processing times, and improves throughput by enabling continuous monitoring and adjustment during the polishing process, preventing short circuits and optimizing circuit resistance.
Implementation Method 1
an oscillating magnetic field is applied to a metal film (or conductive film) formed on a substrate
Implementation Method 2
an eddy current sensor... in which a sensor coil comprises an oscillation coil connected to a signal source, a detection coil for detecting the eddy current produced in the metal film (or conductive film)
Data Source
AI summary
An eddy current sensor is used for detecting a metal film (or conductive film) formed on a surface of a substrate such as a semiconductor wafer. The eddy current sensor includes a sensor coil disposed near a metal film or a conductive film formed on a substrate, and the sensor coil includes a detection coil operable to detect an eddy current produced in the metal film or the conductive film. The detection coil includes a coil formed by winding a wire by a single row and plural layers, the row being defined as a direction perpendicular to the substrate and the layer being defined as a direction parallel to the substrate.