Electrostatic Chuck Polar Regions for Wafer De-chucking
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Solution Overview
Problem
Residual electrostatic charge on semiconductor wafers after processing complicates efficient separation from electrostatic chucks, and uncontrolled lift pin forces can damage the wafers during de-chucking.
Innovation Solution
An electrostatic chuck with zones featuring polar regions around lift pins, controlled by sensors and controllers that adjust upward force and voltage to manage electrostatic forces, ensuring safe and efficient de-chucking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If lift pins are used to raise the semiconductor wafer off the electrostatic chuck, then automated retrieval is facilitated, but uncontrolled lift pin forces can damage the wafer
Solution Approach 1:
The patent implements feedback control by using sensors to detect the actual lift pin forces and electrostatic forces, then feeding this information back to controllers that adjust the lift pin actuation and electrostatic chuck voltage accordingly. This closed-loop control prevents wafer damage by ensuring forces remain within safe limits while enabling automated retrieval operations.
Solution Approach 2:
The patent changes operational parameters dynamically by adjusting both the lift pin forces and the electrostatic chuck voltage based on real-time sensor data. The controller modulates these parameters to achieve safe de-chucking conditions, transforming fixed-force mechanical lifting into a controllable, adaptive process that prevents wafer damage.
2Productivity
If residual electrostatic charge remains on the semiconductor wafer, then de-chucking efficiency is reduced, but complete discharge may cause wafer instability
Solution Approach 1:
The patent applies dynamic control to the electrostatic chuck voltage during the de-chucking process. Rather than using a fixed voltage level, the controller dynamically adjusts the voltage based on sensor feedback, allowing the system to optimize the balance between de-chucking efficiency and wafer stability at different stages of the separation process.
Solution Approach 2:
The patent performs preliminary electrostatic discharge before mechanical lift pin engagement. By applying controlled voltage to the electrostatic chuck zones first, the system reduces residual charge that would otherwise hinder efficient de-chucking, then proceeds with lift pin actuation under controlled conditions that maintain wafer stability.
3Stability of the object's composition
If uniform clamping is achieved through electrical pole pattern design, then processing stability is improved, but de-chucking efficiency may be compromised due to uniform electrostatic distribution
Solution Approach 1:
The patent divides the electrostatic chuck into multiple zones with independently controllable polar regions, allowing different voltage levels to be applied to different areas. During de-chucking, specific zones can be activated to create localized electrostatic forces that facilitate separation, while maintaining uniform clamping during processing through coordinated zone control.
Solution Approach 2:
The patent segments the electrostatic chuck into distinct controllable zones rather than using a single uniform electrode. This segmentation enables independent control of electrostatic forces in different regions, allowing the system to maintain uniform clamping during processing while enabling targeted de-chucking operations by activating specific zones.
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 effectively reduces the risk of wafer damage by precisely controlling lift pin forces and electrostatic forces, facilitating automated and efficient retrieval of semiconductor wafers.
Implementation Method 1
an electrostatic chuck to clamp the semiconductor wafer during such processing, through the use of an electrical pole pattern in the electrostatic chuck
Implementation Method 2
each zone includes one or more polar regions around a lift pin moved by pneumatic pressure
Data Source
AI summary
An apparatus for electrostatic chucking and dechucking of a semiconductor wafer includes an electrostatic chuck with a number of zones. Each zone includes one or more polar regions around a lift pin that contacts a bottom surface of the semiconductor wafer. The apparatus also includes one or more controllers that control the lift pins and one or more controllers that control the polar regions. The controller for the lift pins receives data from one or more sensors and uses the data to adjust the upward force of the lift pins. Likewise, the controller for the polar regions receives data from the sensors and uses the data to adjust the voltage in the polar regions.