CMP Carrier Head Bladder Attachment and Ejection
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Solution Overview
Problem
Conventional carrier heads for chemical mechanical polishing (CMP) of semiconductor wafers are complex, heavy, and difficult to refurbish, with issues in bladder attachment, wafer ejection, and edge control, leading to potential stress on wafers and interference with induction systems.
Innovation Solution
A CMP carrier head design featuring a simplified bladder attachment using spanner nut/clamp ring assemblies made of lightweight, non-conductive materials, an improved ejection system with pneumatic mechanisms to avoid suction, and an edge control system for precise outer edge planarization using selectively pressurizable plenums and annular ribs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple clamp rings and bolts are used to attach the bladder to the carrier head housing, then the bladder attachment is secure, but the overall complexity and weight of the carrier head increases
Solution Approach 1:
The patent combines multiple clamp rings and bolts into a single integrated clamp ring assembly that secures the bladder. This merging of components reduces the overall complexity of the carrier head while maintaining secure bladder attachment, directly resolving the contradiction between reliable attachment and device complexity.
2Reliability
If multiple clamp rings and bolts are used to attach the bladder, then the bladder attachment is secure, but the weight of the carrier head increases
Solution Approach 1:
The patent merges multiple separate clamp rings and bolts into a single integrated clamp ring assembly, reducing the total weight of the carrier head while maintaining secure bladder attachment.
3Reliability
If bolts are tightened to secure the bladder, then the bladder attachment is secure, but high localized clamping force is produced requiring metal housing
Solution Approach 1:
The patent uses a pneumatic or hydraulic actuator to apply distributed pressure to the bladder through the clamp ring assembly, eliminating the need for high localized clamping forces from tightened bolts. This allows the housing to be made from lighter, non-metallic materials while maintaining secure bladder attachment.
4Strength
If metal housing is used to withstand high axial forces, then the housing strength is sufficient, but carrier head interference with induction system occurs
Solution Approach 1:
The patent replaces the metal housing with a pneumatic or hydraulic actuator-based system that applies distributed pressure, eliminating the need for high-strength metal housing. This removes the source of signal attenuation and interference with the induction system while maintaining sufficient force application to the bladder.
5Ease of operation
If central portion of the bladder is expanded to eject the wafer, then the wafer is ejected, but suction is created between the bladder and wafer preventing ejection
Solution Approach 1:
The patent applies local quality by expanding only the outer peripheral edge portion of the bladder to eject the wafer, rather than expanding the central portion. This localized expansion at the periphery avoids creating suction between the bladder and wafer surface, ensuring reliable ejection without the harmful suction effect.
6Device complexity
If conventional carrier head design is used, then the structure is simple, but precise control of outer edge planarization is difficult
Solution Approach 1:
The patent applies local quality by providing independent pressure control for the outer peripheral edge portion of the bladder through a separate pressure chamber or plenum. This allows precise control of the outer edge planarization process, improving manufacturing precision for the wafer's outer edge without significantly increasing overall device complexity.
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 design reduces complexity and weight, facilitates easier maintenance, minimizes stress on wafers during ejection, and enhances precision in planarizing the outer edge of wafers, improving die yields and reducing signal interference.
Implementation Method 1
Multiple pressure chambers or plenums are provided behind the bladder to form a number of annular pressure zones across the bladder's working face. The pressure within each zone is independently adjusted to vary the force applied to the wafer's back surface at different locations.
Implementation Method 2
The induction system may identify thicker wafer surface areas requiring a higher rate of removal
Implementation Method 3
the carrier head ejects the wafer by, for example, expanding a central portion of the bladder to physically force the wafer away therefrom
Data Source
AI summary
A carrier head for supporting a workpiece is provided. The carrier head comprises a mount plate having an aperture therethrough, and a clamp ring having a foot portion and a first leg portion extending therefrom. The first leg portion extends through the aperture, and the foot portion abuts the mount plate proximate the aperture. A flexible bladder has first and second ribs that are received between the mount plate and the foot portion. An annular fastener is removably coupled to the leg portion, and engages the mount plate to cause the first and second ribs to be sealingly secured between the mount plate and the foot portion.