Polishing Head Membrane Inflation via Fluid Storage
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Solution Overview
Problem
The existing polishing apparatuses face challenges in maintaining a stable pressure for inflating the membrane during wafer release, leading to inconsistent membrane inflation and potential wafer breakage or failure to release due to fluctuations in primary-side pressure of the pressure regulator.
Innovation Solution
A method and apparatus where a primary-side valve is closed while a secondary-side valve is opened to store fluid at a pressure adjusted by a pressure regulator in a fluid storage element, and then the stored fluid is supplied to the pressure chamber to inflate the membrane, ensuring a consistent pressure for membrane inflation and proper wafer release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fluid is supplied directly from the primary side of the pressure regulator to the pressure chamber, then the system is simple, but the secondary-side pressure fluctuates with changes in primary-side pressure, causing inconsistent membrane inflation
Solution Approach 1:
The fluid supply system is segmented into primary-side and secondary-side circuits. The primary side handles high-pressure fluid supply from the pressure regulator, while the secondary side delivers controlled fluid to the membrane pressure chamber. This segmentation isolates the membrane inflation process from primary-side pressure fluctuations, ensuring consistent secondary-side pressure regardless of primary-side variations.
Solution Approach 2:
A pressure control mechanism acts as an intermediary between the primary-side pressure regulator and the secondary-side membrane inflation system. This intermediary component buffers and stabilizes the pressure transmitted to the membrane, preventing direct transmission of primary-side pressure fluctuations and ensuring reliable, consistent membrane inflation.
2Ease of operation
If the membrane is not properly inflated, then the wafer is not released from the polishing head, but excessive inflation may cause wafer breakage
Solution Approach 1:
The system incorporates feedback control where the actual pressure in the pressure chamber is monitored and used to adjust the fluid supply to the membrane. This feedback mechanism ensures the membrane is inflated to the precise pressure needed for reliable wafer release without excessive pressure that could cause wafer breakage, maintaining optimal pressure within a specified range.
Solution Approach 2:
The system dynamically adjusts the pressure parameter of the fluid supplied to the membrane based on process requirements. By controlling the secondary-side pressure independently of primary-side fluctuations, the system maintains pressure within an optimal range that ensures complete wafer release while preventing wafer damage from excessive inflation.
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 allows for reliable and reproducible inflation of the membrane, even with changes in primary-side pressure, ensuring proper wafer release and preventing breakage by maintaining a stable secondary-side pressure for membrane inflation.
Implementation Method 1
This pressure chamber is supplied with a fluid, such as air, to press the wafer against the polishing surface of the polishing pad through the membrane under a fluid pressure
Implementation Method 2
Releasing of the wafer is performed by supplying a fluid into the pressure chamber to deform a wafer holding surface of the membrane
Implementation Method 3
The wafer is brought into sliding contact with the polishing surface in the presence of the polishing liquid, so that the surface of the wafer is polished
Data Source
AI summary
A polishing method which can properly inflate a membrane of a polishing head when a substrate, such as a wafer, is released from the polishing head, is disclosed. In this method, the substrate is polished while moving a polishing table and the polishing head relative to each other. The polishing head has a substrate holding surface and a membrane formed by a membrane. Further, a secondary-side valve is closed and a primary-side valve is opened, thereby storing a fluid, having a pressure adjusted by a pressure regulator, in a fluid storage element. The primary-side valve is then closed and the secondary-side valve is opened to supply the fluid from the fluid storage element into a pressure chamber of the polishing head, thereby inflating the membrane to form a gap between the substrate and the membrane. A releasing shower is ejected into this gap to thereby release the polished substrate from the polishing head.