CMP Polishing Head with Segmented Pressure Chambers
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Solution Overview
Problem
Conventional chemical mechanical polishing (CMP) methods struggle to achieve uniform film thickness on semiconductor wafers due to variations in the radial direction, making it difficult to maintain the difference between maximum and minimum film thickness within an allowable range, which affects the polishing process and the final film thickness distribution.
Innovation Solution
A polishing apparatus with a polishing head featuring concentrically divided pressure chambers and a film thickness sensor that adjusts pressure based on specific positions on the wafer to reduce the difference between target and average film thickness values, ensuring uniformity by actively polishing thicker or thinner areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP methods are used with average pressure control, then the polishing process is simple, but the film thickness uniformity deteriorates due to radial variations
Solution Approach 1:
The polishing head is divided into multiple concentric pressure chambers (first, second, third pressure chambers) that can independently control pressure in different radial regions. This segmentation allows targeted pressure adjustment to compensate for radial film thickness variations, improving uniformity without requiring complete system redesign
Solution Approach 2:
Different pressure chambers apply different pressure levels to different radial regions of the wafer. The first pressure chamber applies higher pressure to the center region, while the second and third pressure chambers apply progressively lower pressure to outer regions, creating local quality variations that compensate for initial film thickness non-uniformity
2Manufacturing precision
If pressure is adjusted to compensate for radial variations, then film thickness uniformity improves, but the control system complexity increases
Solution Approach 1:
A film thickness sensor detects the actual film thickness at multiple radial positions, and the control unit uses this feedback information to automatically adjust the pressure in each pressure chamber. This closed-loop feedback system simplifies operation by automating the compensation process based on real-time measurements
Solution Approach 2:
The system performs preliminary measurements of film thickness distribution before polishing, and pre-calculates the required pressure compensation values for each pressure chamber. This preliminary action allows the actual polishing process to proceed with automated pressure adjustment, reducing operational complexity during polishing
3Manufacturing precision
If multiple pressure chambers are used for regional control, then film thickness uniformity improves, but the device complexity increases
Solution Approach 1:
The polishing head is divided into multiple concentric pressure chambers (first, second, third pressure chambers) that can independently control pressure in different radial regions. This segmentation allows targeted pressure adjustment to compensate for radial film thickness variations, improving uniformity without requiring complete system redesign
Solution Approach 2:
Multiple pressure chambers are combined within a single polishing head structure, sharing common components such as the wafer support surface and overall housing. This merging approach achieves regional pressure control while minimizing the increase in overall device complexity through efficient spatial arrangement and shared infrastructure
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 improves the uniformity of film thickness across the wafer by dynamically adjusting pressure in real-time, effectively managing variations and maintaining the film thickness within a predetermined range, enhancing the overall polishing process.
Implementation Method 1
a film thickness sensor embedded in the polishing table, the film thickness sensor being configured to output a signal corresponding to a film thickness of the substrate
Implementation Method 2
a polishing head having a plurality of concentrically divided pressure chambers, for pressing a substrate against the polishing surface of the polishing pad
Implementation Method 3
the wafer slides into contact with the polishing surface by relatively moving the polishing table and the polishing head, and the surface of the wafer is polished
Implementation Method 4
the surface of the wafer is polished
Data Source
AI summary
The present invention relates to a polishing apparatus and a polishing method. The polishing apparatus includes an operation controller (9) configured to control a pressure in each of a plurality of pressure chambers. The operation controller (9) is configured to control the pressure in the pressure chamber of the polishing head (1) corresponding to a specific position so that a difference between a control target film thickness value and an average film thickness value of the entire substrate is reduced.