Wafer Inspection Stage Brake Control for Tilt-Free Positioning
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Solution Overview
Problem
Existing inspection devices face issues with stage tilting during wafer electrical inspection due to load applied by probe cards, leading to inaccuracies in positioning and increased power consumption.
Innovation Solution
A stage system with a substrate support, lifters, and a controller that coordinates the thrust force of a drive motor and brake holding force of an electromagnetic brake to stabilize the substrate position, reducing power consumption and maintaining accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive motor continuously outputs thrust force to maintain substrate position, then positioning stability is improved, but power consumption increases
Solution Approach 1:
The electromagnetic brake operates periodically rather than continuously - it is activated only when the substrate position needs to be maintained or adjusted. The controller selectively applies the brake holding force during positioning phases and releases it during movement phases, converting continuous action into periodic action to reduce overall power consumption while maintaining positioning stability when required
Solution Approach 2:
The electromagnetic brake acts as an intermediary force between the drive motor and the substrate. Instead of the drive motor continuously counteracting gravity, the electromagnetic brake provides supplemental holding force only when needed, mediating the load on the drive motor and enabling energy-efficient positioning maintenance without requiring continuous motor operation
2Measurement precision
If the electromagnetic brake applies strong brake holding force to prevent substrate descent, then positioning accuracy is improved, but stage tilting increases due to unbalanced forces
Solution Approach 1:
The brake holding force is applied selectively to specific lifters rather than uniformly across all lifters. The controller determines which individual lifters require brake application based on real-time position feedback and load distribution, applying localized brake force only where needed to maintain positioning accuracy without creating unbalanced forces that would cause stage tilting
Solution Approach 2:
The brake holding force is dynamically adjusted rather than applied at fixed intensity. The controller continuously monitors substrate position and lifters' load conditions, modulating the electromagnetic brake's holding force in real-time to provide exactly the amount of force needed for positioning accuracy while maintaining stage levelness, converting static brake application into dynamic control
3Force
If multiple lifters are used to support the substrate, then load distribution is improved, but coordinating thrust force and brake holding force becomes more complex
Solution Approach 1:
The controller implements feedback control by continuously monitoring the position of the substrate and the status of each lifter, then adjusting the brake holding force on individual lifters accordingly. This closed-loop feedback system automatically coordinates the multiple lifters, managing the complexity of coordinating thrust force and brake holding force across multiple actuators through real-time sensing and adaptive 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
The coordinated control of drive motor and electromagnetic brake ensures stable load reception and precise positioning with reduced power consumption, minimizing tilting and improving inspection accuracy.
Implementation Method 1
each of the one or more lifters includes a drive motor configured to output a thrust force to raise and lower the substrate support based on rotation
Implementation Method 2
an electromagnetic brake configured to apply a brake holding force to the one or more lifters to maintain a height position of the substrate support
Data Source
AI summary
A stage includes a substrate support configured to support a substrate, one or more lifters configured to raise and lower the substrate support, and a controller configured to control operations of the one or more lifters. Each of the one or more lifters includes a drive motor configured to output a thrust force to raise and lower the substrate support based on rotation, and an electromagnetic brake configured to apply a brake holding force to the one or more lifters to maintain a height position of the substrate support. The controller controls the height position of the substrate support while mutually linking the thrust force of the drive motor and the brake holding force of the electromagnetic brake.