Pressurized Cap Polishing Head for Wafer Flatness Control
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Solution Overview
Problem
Conventional polishing machines for semiconductor and solar wafers suffer from unacceptable flatness parameters due to pad wear, leading to issues like 'dishing' and 'doming', resulting in increased costs and downtime for frequent pad replacements.
Innovation Solution
A single-side polishing head assembly with a cap that can be pressurized to deflect and adjust the polishing pressure, allowing for control over the shape of the wafer to minimize doming and dishing, and adjust the material removal profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional polishing pad is used for wafer polishing, then the polishing process can be performed, but the pad wear causes degradation of wafer flatness parameters
Solution Approach 1:
The polishing head incorporates a flexible membrane that can dynamically change its shape in response to pressurization, allowing the polishing surface to adapt and compensate for pad wear over time, thereby maintaining wafer flatness parameters throughout the pad's service life
Solution Approach 2:
The system changes the physical state of the polishing head by pressurizing the flexible membrane, transforming it from a flat state to a curved state, which modifies the polishing pressure distribution to compensate for pad wear and maintain manufacturing precision
2Manufacturing precision
If the polishing pad is replaced frequently to maintain flatness, then wafer flatness parameters are maintained, but operational costs and downtime increase
Solution Approach 1:
The flexible membrane polishing head performs self-adjustment by changing its own shape in response to pressurization, automatically compensating for pad wear without requiring external intervention or pad replacement, thereby maintaining productivity while preserving manufacturing precision
Solution Approach 2:
The system takes preliminary action by pressurizing the flexible membrane before significant pad wear occurs, proactively compensating for wear and preventing degradation of wafer flatness parameters, thereby extending pad service life and maintaining operational efficiency
3Device complexity
If a rigid polishing head is used, then the structure is simple, but the ability to control wafer shape and compensate for pad wear is limited
Solution Approach 1:
The polishing head uses a flexible membrane instead of a rigid structure, allowing the membrane to deform and change shape when pressurized, which enables precise control over wafer flatness and compensation for pad wear while adding minimal complexity to the overall device
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 enables precise control over wafer flatness, reducing the need for frequent pad replacements, lowering operational costs, and improving the efficiency of the polishing process by modulating the polishing pressure to achieve optimal wafer shape.
Implementation Method 1
The chamber is configured to be pressurized for deflecting the floor
Implementation Method 2
the floor is spaced from the recessed surface to form a chamber therebetween. The chamber is configured to be pressurized for deflecting the floor
Data Source
AI summary
A polishing head assembly for single side polishing of silicon wafers is provided. The polishing head assembly includes a polishing head and a cap. The polishing head has a recess along a bottom portion, the recess having a recessed surface. The cap is positioned within the recess, and has an annular wall and a floor extending across the annular wall. The floor is spaced from the recessed surface to form a chamber therebetween. The chamber is configured to be pressurized for deflecting the floor. The annular wall is attached to the polishing head with an adhesive.