Non-absorbable Pedestal Pad for CMP Corrosion Prevention
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Solution Overview
Problem
Conventional CMP polishing machines expose polished semiconductor surfaces to the atmosphere during the transition from polishing to cleaning, leading to rapid corrosion of copper wiring, which deteriorates the quality and reliability of semiconductor devices.
Innovation Solution
A polishing machine with a workpiece supporting table pad made of resin, where the surface in contact with the workpiece is non-absorbable to fluids, and a method involving the strategic spraying of cleaning fluid to maintain continuous coverage of the polished surface during the transition, preventing exposure to the atmosphere.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the workpiece is transferred from the polishing stage to the cleaning stage, then the cleaning process can be performed, but the polished surface is exposed to the atmosphere causing rapid corrosion of copper wiring
Solution Approach 1:
A non-absorbable pad is introduced as an intermediary component on the workpiece supporting table to prevent direct contact between the polished surface and the absorbent table surface. This pad serves as a mediator that maintains fluid coverage on the polished surface during transfer operations, preventing atmospheric exposure and corrosion while enabling smooth workpiece handling and cleaning access.
Solution Approach 2:
The non-absorbable pad is prepared in advance on the workpiece supporting table before the workpiece transfer. This preliminary preparation ensures that when the workpiece is placed on the table, the polished surface immediately has a non-absorbent interface that prevents fluid absorption and maintains continuous fluid coverage, preventing corrosion before it can occur during the transfer to the cleaning stage.
2Ease of operation
If a conventional absorbent table pad is used, then the workpiece can be easily supported and transferred, but the polished surface absorbs fluids from the table causing oxidation and corrosion
Solution Approach 1:
The invention applies local quality by making only the surface of the pad that contacts the workpiece non-absorbable, while the rest of the pad structure can remain absorbent or have different properties. This localized modification prevents fluid absorption at the critical interface between the pad and polished surface, eliminating oxidation and corrosion, while maintaining the overall workpiece support and transfer functionality.
Solution Approach 2:
The pad is constructed as a composite structure with different material properties in different layers or regions. The surface layer contacting the workpiece is made of non-absorbable material (such as PTFE, polypropylene, or polyethylene) to prevent fluid absorption, while the underlying structure may use different materials for support and flexibility, combining the benefits of non-absorbency at the interface with mechanical support from the composite structure.
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 prevents oxidation and corrosion of metal interconnects, ensuring higher quality and reliability of semiconductor devices by maintaining the polished surface in a protected state until further processing.
Implementation Method 1
at least a surface of the pad which comes into contact with a workpiece is non-absorbable to a fluid
Data Source
AI summary
A pedestal pad (workpiece supporting table pad) is arranged on the top of a pedestal (workpiece supporting table) for temporarily placing and holding a pre-polished or post-polished wafer (workpiece). This pedestal pad is formed of resin, and at least a surface of the pedestal pad which comes into contact with the wafer is non-absorbable to a fluid. The tissue of the pedestal pad is dense and smooth, and does not have any cavity, such as fine holes, which holds the fluid.