CMP Polishing Head Fluid Removal via Reversed Chamber Pressurization
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Solution Overview
Problem
The presence of fluid, such as cleaning liquid or air, between the upper surface of a workpiece and the polishing head in chemical mechanical polishing (CMP) can prevent the application of appropriate forces to the workpiece, leading to unintended force application and reduced polishing effectiveness.
Innovation Solution
A polishing method and apparatus that utilize a polishing head with multiple pressure chambers, where the fluid is forced to flow out by sequentially pressurizing the chambers from the center to the outer regions, ensuring the elastic membrane applies consistent forces to the workpiece by maintaining pressure differences across the chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the inner pressure chamber is pressurized and then the outer pressure chamber is pressurized, then the fluid can be moved outward from the workpiece surface, but the inflation of the elastic membrane becomes unbalanced and the bottom of the elastic membrane is pulled toward the outer pressure chamber, causing pressure loss in the inner pressure chamber and potential fluid flow backward
Solution Approach 1:
The patent applies preliminary action by pressurizing the outer pressure chamber before the inner pressure chamber. This reversed sequence prevents the elastic membrane from becoming unbalanced during fluid removal, as the outer chamber is already pressurized to provide support before the inner chamber inflation begins. This eliminates the problem of the membrane bottom being pulled toward the outer chamber and prevents pressure loss in the inner chamber.
Solution Approach 2:
The patent inverts the conventional pressurization sequence by pressurizing the outer pressure chamber first and then the inner pressure chamber, rather than the traditional inner-to-outer sequence. This inversion resolves the technical contradiction by preventing elastic membrane imbalance and ensuring stable pressure application throughout the fluid removal process.
2Ease of operation
If sequential pressurization from center to outer is used to remove fluid, then fluid can flow out from the workpiece, but the elastic membrane inflation becomes unbalanced causing pressure transmission issues
Solution Approach 1:
The outer pressure chamber is pressurized in advance before the inner pressure chamber, creating a stable support structure for the elastic membrane before fluid removal begins. This preliminary action ensures that when the inner chamber is pressurized to remove fluid, the membrane remains balanced and maintains consistent force application across the workpiece surface.
Solution Approach 2:
The patent inverts the pressurization sequence from the conventional inner-to-outer approach to an outer-to-inner approach. This inversion ensures that the elastic membrane inflates in a balanced manner, preventing unbalanced force application and maintaining manufacturing precision while effectively removing fluid from the workpiece surface.
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 approach effectively removes fluid from the workpiece surface, allowing the polishing head to apply appropriate and consistent forces, thereby improving the polishing process and preventing fluid from interfering with the force application.
Implementation Method 1
pressurizing the first pressure chamber to move fluid present between an upper surface of the workpiece and the first pressure chamber outward
Implementation Method 2
a polishing head having a plurality of pressure chambers formed by an elastic membrane
Data Source
AI summary
A polishing method and a polishing apparatus that can suppress fluid from remaining on an upper surface of a workpiece, and that can apply an appropriate force to the workpiece to polish the workpiece are disclosed. The polishing method includes: pressurizing a first pressure chamber to move fluid present between an upper surface of the workpiece and the first pressure chamber outward; moving the fluid present between the upper surface of the workpiece and a second pressure chamber outward by pressurizing the second pressure chamber to form a second pressure in the second pressure chamber which is lower than a target pressure when a pressure equal to or higher than the target pressure is formed in the first pressure chamber; and polishing the workpiece after causing the fluid to flow out from the workpiece.