Magnetron Sputtering Target Wear Detection by Magnetic Field Measurement
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Solution Overview
Problem
Current methods for determining target replacement timing in magnetron sputtering processes are inefficient, requiring pre-processing that increases costs and leads to early target replacement due to variable wear rates, causing suboptimal use of the target and potential contamination or cracking.
Innovation Solution
A film forming apparatus that includes a magnetron sputtering method with a magnetic field strength measurement device to determine target replacement timing based on the increasing magnetic field strength as the target wears, allowing for real-time prediction of remaining target thickness without pre-processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pre-processing is performed to determine target replacement timing, then target replacement can be detected, but manufacturing costs increase and target usage efficiency decreases
Solution Approach 1:
The patent replaces the mechanical pre-processing method (cutting back grooves) with a magnetic field measurement system. A magnet is attached to the target holder, and a magnetic field strength measurement device measures the magnetic field strength through the target. As the target wears down, the magnetic field strength changes, providing a non-contact, non-invasive method to detect target replacement timing without additional manufacturing costs.
Solution Approach 2:
The patent introduces a magnet as an intermediary element attached to the target holder. The magnet serves as a mediator that allows indirect measurement of target thickness through magnetic field strength variations. This intermediary enables detection without direct contact or modification of the target itself, eliminating the need for pre-processing.
2Measurement precision
If pre-processing is performed on the target, then target wear can be detected, but the target is subjected to additional stress that may cause cracking
Solution Approach 1:
The patent replaces mechanical contact methods (cutting, scratching) with a magnetic field-based measurement system. The magnet and measurement device provide non-contact detection, eliminating mechanical stress on the target that could lead to cracking or structural damage.
Solution Approach 2:
The target itself serves as the measurement medium without requiring external modification. The magnetic field passes through the target, and the target's inherent properties (thickness, material composition) directly influence the measured magnetic field strength, allowing detection without external intervention or stress application.
3Object-affected harmful factors
If early target replacement is performed, then contamination can be prevented, but target usage efficiency decreases and costs increase
Solution Approach 1:
The patent implements a feedback mechanism where magnetic field strength measurements continuously monitor target wear. The system provides real-time information about target condition, allowing replacement decisions to be based on actual wear levels rather than predetermined schedules. This enables optimal replacement timing that prevents contamination while maximizing target usage.
Solution Approach 2:
The patent transitions from static, predetermined replacement schedules to dynamic, condition-based replacement. The magnetic field measurement system continuously adapts to the target's actual wear state, allowing the replacement timing to be optimized based on real-time conditions rather than fixed intervals.
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 accurate and timely target replacement, maximizing target usage while preventing contamination and cracking, and reducing costs by eliminating the need for pre-processing, thus improving the efficiency and reliability of the film formation process.
Implementation Method 1
a magnet provided on a surface of the target holder opposite to the substrate holder, and configured to leak a magnetic field to a front surface of the target held by the target holder that is a surface close to the substrate holder
Implementation Method 2
a magnetic field strength measurement device configured to measure a strength of the magnetic field
Data Source
AI summary
A film forming apparatus for forming a film on a substrate by using a magnetron sputtering method. The film forming apparatus includes: a substrate holder configured to hold a substrate; a target holder configured to hold a target made of a ferromagnetic material to face the substrate holder; a magnet provided on a surface of the target holder opposite to the substrate holder, and configured to leak a magnetic field to a front surface of the target held by the target holder that is a surface close to the substrate holder; and a magnetic field strength measurement device configured to measure a strength of the magnetic field.