Electrostatic Chuck Clamping Force Control via Deflection Sensors
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Solution Overview
Problem
In semiconductor manufacturing, electrostatic chucks often apply excessive clamping forces, leading to workpiece damage such as craters and particulates, due to manufacturing variances and environmental effects, necessitating a more consistent and predictable clamping force to ensure uniform quality and reduce defects.
Innovation Solution
A control system utilizing deflection sensors to measure the workpiece's deflection into recesses of the electrostatic chuck, allowing a controller to adjust the clamping force by applying a clamping voltage to maintain a target force, minimizing damage while securing the workpiece.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clamping force is increased to provide a factor of safety against manufacturing variances and environmental effects, then the reliability of workpiece holding is improved, but the workpiece may suffer damage such as craters, embedded parts, and particulates
Solution Approach 1:
The patent employs feedback control by measuring the actual clamping force applied to the workpiece and adjusting the electrostatic field accordingly. Sensors detect workpiece parameters (such as position, temperature, or electrical properties) and the control system modifies the clamping force in real-time to maintain the optimal force level, preventing both insufficient holding and excessive damage
Solution Approach 2:
The patent dynamically changes the clamping force parameter based on measured workpiece conditions. By adjusting the electrostatic field strength according to real-time feedback about workpiece state (temperature, position, material properties), the system adapts the clamping force to match actual needs rather than applying a fixed high force
2Object-affected harmful factors
If the clamping force is reduced to minimize workpiece damage, then the harmful factors affecting the workpiece are reduced, but the workpiece may not be securely held during manufacturing operations
Solution Approach 1:
The feedback mechanism continuously monitors workpiece conditions and adjusts clamping force upward when needed to maintain secure holding. The control system responds to changes in workpiece state (such as thermal expansion, position drift, or material property changes) by increasing the electrostatic field strength to ensure adequate clamping force is applied
3Reliability
If a fixed high clamping force is applied to accommodate manufacturing variances, then the workpiece holding is reliable under varying conditions, but the precision and uniformity of workpiece quality deteriorates due to overchucking
Solution Approach 1:
The patent changes the clamping force parameter dynamically based on measured workpiece conditions rather than applying a fixed high force. By adjusting the electrostatic field strength according to real-time feedback about individual workpiece characteristics (temperature, position, material properties), the system maintains consistent holding reliability while preventing the uniform overchucking that causes quality defects
Solution Approach 2:
The patent applies different clamping force levels to different regions or individual workpieces based on their specific conditions. By measuring local workpiece parameters and adjusting the electrostatic field accordingly, the system provides customized clamping force where needed rather than applying uniform high force across all workpieces
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 system effectively controls clamping forces to prevent workpiece damage, ensuring consistent quality and reducing defects by maintaining a precise and predictable clamping force, even with varying manufacturing conditions.
Implementation Method 1
an electrostatic force ('clamping force') of the electrostatic chuck to precisely hold the workpiece
Implementation Method 2
a sensor positioned to determine a deflection of a workpiece into at least one recess of the electrostatic chuck
Data Source
AI summary
A control system that includes deflection sensors which can control clamping forces applied by electrostatic chucks, and related methods are disclosed. By using a sensor to determine a deflection of a workpiece supported by an electrostatic chuck, a control system may use the deflection measured to control a clamping force applied to the workpiece by the electrostatic chuck. The control system applies a clamping voltage to the electrostatic chuck so that the clamping force reaches and maintains a target clamping force. In this manner, the clamping force may secure the workpiece to the electrostatic chuck to enable manufacturing operations to be performed while preventing workpiece damage resulting from unnecessary higher values of the clamping force.