Vertically Movable Top Ring for Semiconductor Wafer Polishing
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Solution Overview
Problem
Conventional top ring systems for semiconductor wafer polishing face challenges in achieving precise control over the vertical position and pressure distribution, leading to deformation and stress on the wafer, which can result in defects or damage during the polishing process.
Innovation Solution
A polishing method and apparatus that utilizes a vertically movable top ring with a membrane-based pressure chamber, allowing for controlled movement between two heights to minimize deformation and stress, and employs sensors for detecting contact and pressure changes to optimize polishing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the top ring is lowered to bring the polishing pad, substrate and membrane into close contact before applying pressure, then fluid leakage is prevented, but the substrate may be deformed or damaged due to excessive stress during pressure application
Solution Approach 1:
The top ring is lowered to a first height before pressure application to establish close contact between the polishing pad, substrate and membrane, ensuring proper sealing and positioning before the harmful pressure is applied. This preliminary positioning action prevents fluid leakage while preparing the system for controlled pressure application.
Solution Approach 2:
The top ring's vertical position is dynamically adjusted between two heights: a first height during pressure application to minimize substrate deformation, and a second height during polishing to maintain optimal contact. This dynamic positioning resolves the contradiction between sealing reliability and substrate protection.
2Productivity
If pressure is applied to the membrane while the substrate is in close contact with the polishing pad, then polishing effectiveness is improved, but the substrate experiences excessive stress and deformation
Solution Approach 1:
The system dynamically adjusts the top ring's vertical position based on the polishing phase: positioned at a first height during pressure application to reduce substrate stress, and at a second height during the polishing phase to optimize contact and effectiveness. This dynamic control allows the system to achieve both productivity and substrate protection.
Solution Approach 2:
The vertical position parameter of the top ring is changed between two discrete values (first height and second height) to control the degree of contact between the substrate and polishing pad. This parameter change enables the system to switch between stress-reduction mode and effectiveness-optimization mode.
3Manufacturing precision
If the vertical position of the top ring is precisely controlled, then substrate deformation is minimized, but the device complexity increases
Solution Approach 1:
The top ring is designed with dynamic vertical movement capability, allowing it to adjust its position between two heights. This dynamic feature enables precise control of the substrate's vertical position during different phases of the polishing process, minimizing deformation while maintaining manageable device complexity through controlled mobility rather than rigid positioning.
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 method and apparatus effectively reduce deformation and stress on the semiconductor wafer, enhancing the precision and safety of the polishing process while preventing defects and damage.
Implementation Method 1
a fluid such as air is supplied to a pressure chamber (pressurizing chamber) formed above the chucking plate and a pressure chamber formed by the elastic membrane (membrane) to press a semiconductor wafer against a polishing pad under a fluid pressure through the elastic membrane
Implementation Method 2
a polishing liquid containing abrasive particles such as silica (SiO2) therein is supplied onto a polishing surface such as a polishing pad, a substrate such as a semiconductor wafer is brought into sliding contact with the polishing surface, so that the substrate is polished
Implementation Method 3
a substrate such as a semiconductor wafer is brought into sliding contact with the polishing surface, so that the substrate is polished
Data Source
AI summary
A polishing method is used for polishing a substrate such as a semiconductor wafer to a flat mirror finish. A method of polishing a substrate by a polishing apparatus includes a polishing table (100) having a polishing surface, a top ring (1) for holding a substrate and pressing the substrate against the polishing surface, and a vertically movable mechanism (24) for moving the top ring (1) in a vertical direction. The top ring (1) is moved to a first height before the substrate is pressed against the polishing surface, and then the top ring (1) is moved to a second height after the substrate is pressed against the polishing surface.