Deformable Substrate Chuck With Zoned Pressure for CMP Uniformity
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Solution Overview
Problem
Chemical mechanical polishing (CMP) processes face challenges in achieving uniformity across substrates due to variations in substrate shape and stiffness, leading to non-uniform pressure distribution and over-polishing of certain regions.
Innovation Solution
A deformable substrate chuck with independently pressurizable micro-zones and macro-zones, coupled with pneumatic control lines, allows for shape-based pressure distribution according to the substrate's shape and polishing pad stiffness, enabling precise control of substrate shape and pressure application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If uniform pressure is applied across the substrate during CMP, then the polishing process is simple to control, but non-uniformity occurs due to variations in substrate shape and stiffness
Solution Approach 1:
The support plate is divided into multiple independently pressurizable zones (first zones and second zones), allowing different pressure levels to be applied to different regions of the substrate. This segmentation enables precise control of pressure distribution to compensate for substrate shape variations and achieve uniform polishing across the wafer surface.
Solution Approach 2:
Different zones of the support plate are assigned different pressure characteristics - some zones apply higher pressure while others apply lower pressure, tailored to the local requirements of substrate regions. This local quality approach ensures that each area of the substrate receives the appropriate pressure needed to maintain uniformity, rather than applying a single uniform pressure across the entire substrate.
2Manufacturing precision
If the substrate is rigidly held during polishing, then positioning is stable, but the substrate cannot adapt to pressure distribution requirements for uniform polishing
Solution Approach 1:
The support plate transitions from a rigid structure to a dynamically adjustable structure with multiple independently pressurizable zones. This allows the substrate holding system to adapt its pressure distribution in real-time based on substrate shape variations, enabling the system to respond to different polishing requirements for different wafer regions while maintaining stable positioning.
Solution Approach 2:
The pressurizable zones allow independent adjustment of pressure parameters across different regions of the substrate. By changing pressure parameters in specific zones, the system can accommodate variations in substrate shape and stiffness, enabling the substrate to adapt to the pressure distribution requirements for uniform polishing without compromising positioning stability.
3Manufacturing precision
If pressure is applied without considering substrate shape, then the process is simple, but over-polishing occurs in certain regions
Solution Approach 1:
The system incorporates sensors that detect substrate shape and position information, which is fed back to the pressure control system. This feedback enables the pressure distribution to be automatically adjusted according to the actual substrate configuration, preventing over-polishing in certain regions while ensuring uniform polishing across the entire wafer surface.
Solution Approach 2:
Before polishing begins, the support plate pressure zones are pre-configured based on expected substrate shape variations. This preliminary action allows the system to be prepared with appropriate pressure distribution patterns that anticipate and compensate for substrate non-uniformities, preventing over-polishing before it occurs rather than requiring complex real-time adjustments during the polishing process.
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 solution improves within-wafer and wafer-to-wafer uniformity by tailoring pressure distribution, reducing over-polishing and enhancing the precision of the polishing process through in-situ metrology feedback for pressure adjustment.
Implementation Method 1
The volume between the support plate and the housing includes one or more independently pressurizable first chambers to apply pressure on a top surface of the support plate
Implementation Method 2
a support assembly having a support plate flexibly connected to the housing so as to be vertically movable relative to the housing
Data Source
AI summary
A carrier head includes a housing, a support assembly having a support plate flexibly connected to the housing so as to be vertically movable, a plurality of fluid-impermeable barriers projecting from a bottom of the support plate to define a plurality of recesses that are open at bottom sides thereof, and pneumatic control lines. A volume between the support plate and the housing includes one or more independently pressurizable first chambers to apply pressure on a top surface of the support plate in one or more first zones. The barriers are positioned and configured such that when a planar substrate is loaded into the carrier head the barriers contact the substrate and divide a volume between the support plate and the substrate into a plurality of second chambers. The pneumatic control lines are coupled to the plurality of recesses to provide a plurality of independently pressurizable second zones.