CMP Carrier Head Notch Sensing for Thickness Asymmetry
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Solution Overview
Problem
Chemical mechanical polishing (CMP) processes often result in substrates with asymmetric thickness profiles, leading to varying RC time constants and processing speeds across integrated circuits due to non-uniform material removal, affecting the quality of integrated circuits.
Innovation Solution
A carrier head system with a pixel cartridge array and notch sensor array is used to determine the angular position of a substrate notch, allowing for localized pressure application to correct thickness asymmetry during polishing, using a controller to adjust pressure based on the substrate's thickness profile and angular position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If symmetric CMP process is used, then material removal is uniform and simple to control, but substrates with asymmetric thickness profiles remain asymmetric after polishing
Solution Approach 1:
The patent applies asymmetric pressure distribution across the carrier head by dividing it into multiple independently controllable zones. Each zone can apply different downforce to correspond with asymmetric thickness profiles detected by notch sensors, transforming the symmetric process into an asymmetric one that compensates for substrate variations and achieves uniform final thickness.
Solution Approach 2:
The patent implements local quality control by dividing the carrier head into multiple zones that can be independently adjusted. Each zone applies customized pressure based on local thickness measurements, allowing different regions of the substrate to receive appropriate polishing pressure according to their specific thickness requirements.
2Manufacturing precision
If asymmetric pressure distribution is applied to correct thickness asymmetry, then thickness uniformity is improved, but device complexity increases due to multiple sensors and actuators
Solution Approach 1:
The patent segments the carrier head into multiple independently controllable zones, each equipped with its own actuators and controlled by the controller based on local thickness profile data. This segmentation enables precise localized control while maintaining modular architecture that manages system complexity through standardized components.
Solution Approach 2:
The patent implements feedback control by using notch sensors to detect substrate thickness profile and angular position, feeding this information to the controller which then adjusts the pressure distribution across different zones in real-time. This closed-loop feedback system automatically compensates for variations and reduces the need for manual intervention.
3Manufacturing precision
If multiple independently controllable zones are used, then localized planarization is achieved, but the number of components and control complexity increases
Solution Approach 1:
The patent designs each actuator zone to serve multiple functions: applying pressure for polishing, detecting through integrated sensors, and responding to control signals based on both thickness profile and angular position data. This multi-functionality reduces the need for separate dedicated components for each function.
Solution Approach 2:
The patent implements dynamic control by allowing real-time adjustment of pressure distribution across different zones based on feedback from thickness measurements and angular position detection. The system adapts its pressure profile during the polishing process to optimize planarization while managing complexity through algorithmic control rather than hardware complexity.
Data Source
AI summary
Embodiments of the disclosure provided herein include systems and methods for correcting thickness asymmetry of a substrate during chemical mechanical polishing. The system includes a carrier head with a pixel cartridge array disposed within a carrier head body and a membrane adjacent to the pixel cartridge array, a notch sensor array disposed on a carrier ring, and a controller coupled to the pixel cartridge array and the notch sensor array. The controller is configured to receive and orient a substrate such that the substrate is an oriented substrate, determine a thickness profile on the oriented substrate, position the oriented substrate in a loading position, receive the oriented substrate, and polish the oriented substrate use the pixel cartridge array. The pixel cartridge array is configured to apply pressure on a membrane of a carrier head in a chemical mechanical polishing system.