Stepwise Connection Pad Layout for Crack-Resistant Electrostatic Chucks
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Solution Overview
Problem
The electrostatic chuck with internal wiring is prone to damage due to the difference in thermal expansion coefficients between the ceramic and conductive connection pads, leading to stress and potential cracks during high-temperature firing.
Innovation Solution
The connection pads in the electrostatic chuck are arranged stepwise, reducing their overlapping and thus the mounting density, and connected through vias to minimize stress from thermal expansion differences, thereby reducing the risk of damage to the ceramic and conductive pads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If connection pads are arranged in overlapping layers to establish electrical connections through the ceramic plate, then electrical connectivity is achieved, but stress concentration occurs due to difference in thermal expansion coefficients between ceramic and conductive materials
Solution Approach 1:
The connection pads are arranged in a stepwise pattern across multiple layers, transitioning from a conventional overlapping configuration to a distributed spatial arrangement. This dimensional redistribution reduces the concentration of conductive material in any single location, thereby reducing stress concentration while maintaining electrical connectivity through the multi-layer structure.
Solution Approach 2:
Different regions of the ceramic plate are designed with varying connection pad densities. The stepwise arrangement creates zones with different material concentrations, allowing areas with higher stress risk to have reduced conductive material presence while maintaining necessary electrical connections in other regions. This local optimization balances connectivity requirements with stress resistance.
2Ease of manufacture
If green sheets with connection pads are arranged and fired to form the ceramic plate with internal wiring, then internal wiring structure is achieved, but cracks may occur during high-temperature firing due to thermal expansion differences
Solution Approach 1:
The connection pads are pre-positioned in a stepwise pattern on the green sheets before firing. This preliminary arrangement ensures that the conductive material is distributed in a stress-reducing configuration from the outset of the manufacturing process, preventing stress concentration and crack formation during the subsequent high-temperature firing process.
Solution Approach 2:
The invention uses a composite structure combining ceramic green sheets with integrated conductive connection pads. This composite approach allows the ceramic matrix to provide mechanical strength and thermal stability while the distributed conductive elements provide electrical connectivity, with the stepwise arrangement optimizing the balance between these competing requirements during firing.
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
This arrangement reduces the stress and likelihood of cracks in the electrostatic chuck by lowering the connection pad density and distributing thermal stress more evenly, enhancing the chuck's durability and reliability.
Implementation Method 1
Due to a voltage applied to the adsorption electrode built in the ceramic plate, the wafer is adsorbed on the electrostatic chuck by electrostatic force
Implementation Method 2
stress is generated at a boundary between the connection pads and the ceramic due to the difference in coefficient of thermal expansion during firing in which the green sheets are heated at high temperature
Data Source
AI summary
An electrostatic chuck includes: a ceramic plate; an adsorption electrode that is built in the ceramic plate; and a plurality of connection pads that are built in the ceramic plate to be electrically connected to the adsorption electrode. The connection pads are arranged stepwise.