CMP Polishing Head Zonal Pressure Control via Piezoelectric Layer
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Solution Overview
Problem
Current chemical-mechanical polishing (CMP) systems face challenges in achieving uniformity due to asymmetric topography of the polish profile, as existing designs lack effective control over localized force distribution on substrates during the polishing process.
Innovation Solution
The CMP system incorporates a polishing head with individually actuable pressure units and a piezoelectric layer to exert controlled forces on the substrate, allowing for zonal control of the polish profile by isolating pressure chambers and using voltage differences to adjust forces based on the substrate's profile, ensuring even material removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional polishing head design is used, then the polishing process is simple, but asymmetric topography of the polish profile exists and uniformity is poor
Solution Approach 1:
The polishing head is divided into multiple independently controllable pressure units, each capable of applying force to different zones of the substrate. This segmentation allows localized control of polishing pressure to correct asymmetric topography and achieve uniform polish profiles across the substrate surface.
Solution Approach 2:
The polishing head incorporates dynamically adjustable pressure units that can vary the applied force in real-time based on feedback from sensors measuring substrate topography. This dynamic control enables continuous adjustment of polishing pressure to maintain uniform material removal rates across different zones.
2Manufacturing precision
If uniform pressure is applied across the substrate, then the polishing process is simple to control, but asymmetric topography cannot be corrected
Solution Approach 1:
Different zones of the substrate receive customized pressure levels through individually controlled pressure units. Areas with higher protrusions receive greater pressure to remove material faster, while recessed areas receive reduced pressure, creating a localized quality distribution that corrects asymmetric topography and achieves symmetric polish profiles.
Solution Approach 2:
Sensors integrated into the polishing head continuously measure substrate topography and provide feedback to the control system. This feedback enables automatic adjustment of pressure unit forces to maintain desired pressure distribution patterns, simplifying operation while achieving precise symmetric polish profiles through closed-loop control.
3Manufacturing precision
If localized force control is implemented, then asymmetric topography can be addressed, but the number of pressure units increases
Solution Approach 1:
Each pressure unit is designed as a multi-functional module that combines force application, sensing capabilities, and local control functions. This universal design allows a smaller number of sophisticated pressure units to perform the work of multiple simpler units, reducing overall device complexity while maintaining precise localized force control for correcting asymmetric topography.
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 enables precise control over the polish profile, effectively addressing asymmetric topography by applying tailored forces to different zones of the substrate, resulting in a more uniform and planar surface finish.
Implementation Method 1
a piezoelectric layer to exert controlled forces on the substrate, allowing for zonal control of the polish profile by isolating pressure chambers and using voltage differences to adjust forces
Data Source
AI summary
A method includes supplying slurry onto a polishing pad; holding a wafer against the polishing pad with a piezoelectric layer interposed vertically between a pressure unit and the wafer; exerting a force on the piezoelectric layer using the pressure unit to make the piezoelectric layer directly press the wafer; generating, using the piezoelectric layer, a first voltage corresponding to a first portion of the wafer and a second voltage corresponding to a second portion of the wafer; tuning the force exerted on the piezoelectric layer according to the first voltage and the second voltage; and polishing, using the polishing pad, the wafer.