Chuck Table Mechanism for Warping Workpiece Holding
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Solution Overview
Problem
Existing chuck table mechanisms struggle to securely hold warping workpieces, such as wafers, due to the loss of vacuum suction or electrostatic attraction when the workpieces warp during processing, leading to instability and potential detachment.
Innovation Solution
A combined chuck table mechanism incorporating both electrostatic attraction and vacuum suction sections, where electrodes charge the holding surface to create an electrostatic force and a suction port system provides negative pressure, allowing for simultaneous application of both forces to securely hold the workpiece.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If strong vacuum suction is used to hold a warping workpiece, then the workpiece can be held initially, but the suction force is insufficient when the workpiece warps during processing
Solution Approach 1:
The patent combines electrostatic attraction and vacuum suction into a unified chuck table mechanism. The electrostatic chuck table provides strong attraction force for warping workpieces, while vacuum suction ports provide additional holding force, creating a synergistic effect that overcomes the limitations of either method alone.
Solution Approach 2:
The chuck table uses a composite structure combining electrostatic attraction surfaces and vacuum suction ports. This composite approach integrates two different physical mechanisms (electrostatic and pneumatic) into a single holding system, allowing the system to leverage the strengths of both methods simultaneously.
2Force
If electrostatic attraction is used to hold a workpiece, then strong suction force can be exerted when in close contact, but the attraction force cannot act when the workpiece warps and comes off the holding surface
Solution Approach 1:
The patent merges electrostatic attraction with vacuum suction to create a redundant holding system. When the workpiece warps and loses electrostatic contact, the vacuum suction ports continue to provide holding force, ensuring continuous reliability throughout the processing operation.
Solution Approach 2:
The vacuum suction ports act as a cushioning backup mechanism that is already in place before warping occurs. When electrostatic attraction fails due to warping, the vacuum system provides immediate compensatory holding force, preventing workpiece detachment.
3Device complexity
If vacuum suction alone is used, then the structure is simple, but the suction force becomes insufficient when the workpiece warps
Solution Approach 1:
The patent combines electrostatic and vacuum systems in an integrated chuck table design. The electrostatic component adds minimal structural complexity while significantly enhancing holding reliability for warping workpieces, creating a balanced solution that addresses both simplicity and effectiveness.
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 combined chuck table mechanism effectively holds warping workpieces by utilizing electrostatic attraction and vacuum suction forces, ensuring reliable retention even when the workpiece warps, thereby preventing detachment during processing.
Implementation Method 1
electrodes provided in the chuck table for charging the holding surface through supply of power and electrostatically attracting the workpiece
Implementation Method 2
a suction port formed in the holding surface to communicate with a suction source
Data Source
AI summary
A combined chuck table mechanism includes a chuck table, an electrostatic attraction section, and a vacuum suction section. The chuck table has a holding surface for holding a plate-shaped workpiece. The electrostatic attraction section has electrodes provided in the chuck table for charging an upper surface, a holding surface, through supply of power and electrostatically attracting the workpiece. The vacuum suction section has a porous portion that is formed to be flush with the upper surface, that communicates with a suction source, and that has fine holes, suction ports. The combined chuck table mechanism further includes a control unit adapted to achieve holding of the workpiece through a combined force by supplying power to the electrodes and a negative pressure to the suction ports.