Polishing Apparatus Dynamic Dressing Force Control
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Solution Overview
Problem
Existing polishing apparatuses face challenges in maintaining a constant cutting force on polishing pads during dressing, leading to uneven polishing performance due to variations in force depending on the position and swinging direction of the dresser.
Innovation Solution
A polishing apparatus with a controller that adjusts the pressing force, turntable rotation speed, and dresser rotation speed based on the position and swinging direction of the dresser to maintain a target cutting force, using a table to determine optimal control signals for each position and direction, ensuring consistent dressing across the polishing pad.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the dresser presses the polishing pad with constant force, then the pressing force is stable, but the cutting force varies due to position and swinging direction
Solution Approach 1:
The patent applies dynamics by transitioning from static constant pressing force control to dynamic control that adjusts pressing force based on dresser position and swinging direction. The control system dynamically modifies the pressing force to compensate for variations in cutting force, ensuring uniform dressing across the polishing pad while accounting for the changing mechanical conditions at different positions and swing directions.
Solution Approach 2:
The patent implements feedback control by using detectors to monitor the actual position and swinging direction of the dresser, then feeding this information back to the controller. The controller processes this feedback and adjusts the pressing force accordingly, creating a closed-loop control system that maintains constant cutting force despite variations in dresser position and swing direction.
2Area of stationary object
If the dresser swings on the polishing pad to cover different positions, then the entire pad surface is dressed, but the cutting force becomes non-uniform
Solution Approach 1:
The patent applies local quality by implementing position-dependent and swing-direction-dependent pressing force control. Different regions of the polishing pad receive appropriately adjusted pressing forces based on their specific location and the dresser's swing direction, ensuring that each local area achieves uniform dressing. This localized control strategy allows the entire pad surface to be dressed uniformly despite the dresser's movement across different positions.
Solution Approach 2:
The patent uses dynamics to adjust the pressing force in real-time as the dresser swings across different positions on the polishing pad. The control system dynamically modifies the pressing force parameters based on the current position and swing direction, enabling uniform dressing coverage across the entire pad surface while compensating for the non-uniform mechanical conditions encountered during swinging motion.
3Productivity
If the pressing force is increased to improve cutting efficiency, then productivity increases, but the force variation across different positions worsens
Solution Approach 1:
The patent applies dynamics by implementing dynamic pressing force control that adjusts the force magnitude based on dresser position and swing direction. This allows the system to maintain high productivity through appropriately elevated pressing forces while simultaneously ensuring uniform cutting force distribution across different positions. The dynamic adjustment prevents the force variation problems that would result from using a single high constant pressing force throughout the entire dressing process.
Solution Approach 2:
The patent implements parameter changes by modifying the pressing force parameter as a function of position and swing direction. Rather than using a fixed high pressing force, the system dynamically changes the pressing force parameter to achieve both high productivity and uniformity. This parameter adjustment strategy allows optimal cutting efficiency at each position while maintaining overall uniformity across the polishing pad surface.
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 ensures uniform dressing of the polishing pad by maintaining a constant cutting force, improving polishing performance and productivity by adjusting the pressing force and rotation speeds dynamically in response to changing frictional coefficients and positions.
Implementation Method 1
a dresser configured to dress the polishing pad by cutting a surface of the polishing pad
Data Source
AI summary
A polishing apparatus according to one embodiment includes: a turn table on which a polishing pad for polishing a substrate is provided; a turn table rotation mechanism configured to rotate the turn table; a dresser configured to dress the polishing pad by cutting a surface of the polishing pad; a pressing mechanism configured to press the dresser onto the polishing pad; a dresser rotation mechanism configured to rotate the dresser; a swinging mechanism configured to swing the dresser on the polishing pad; and a controller configured to control the pressing mechanism, the turn table rotation mechanism or the dresser rotation mechanism based on a position and a swinging direction of the dresser.