Real-Time Polishing Recipe Control for CMP Uniformity
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Solution Overview
Problem
Chemical mechanical polishing (CMP) processes in the semiconductor industry face challenges in achieving consistent polishing rates across different regions of a wafer, leading to inconsistent results due to surface irregularities, despite prior calibrations.
Innovation Solution
An in situ rate monitoring system that collects and analyzes real-time metrology data to identify time deltas in material removal rates across various wafer regions, updating polishing parameters in real-time using a look-up table to adjust pressures applied by the polishing head, ensuring uniform polishing across the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polishing recipes are calibrated to compensate for different polishing rates in sets of wafers, then polishing uniformity across wafer regions is improved, but inconsistent polishing still occurs from wafer to wafer due to surface irregularities
Solution Approach 1:
The system implements real-time feedback control by continuously monitoring material removal rates during polishing and dynamically adjusting polishing parameters. Sensors measure the polishing rate at different wafer regions, and the control system modifies pressure or speed parameters to maintain uniform polishing across all wafers, eliminating the need for repeated calibration while ensuring consistent results.
Solution Approach 2:
The polishing system transitions from static pre-calibrated recipes to dynamic real-time parameter adjustment. The control system continuously adapts polishing parameters based on actual material removal rates measured during the process, allowing the system to respond to surface irregularities and maintain consistent polishing performance across multiple wafers.
2Manufacturing precision
If real-time monitoring and adjustment of polishing parameters is implemented, then polishing consistency is improved, but system complexity increases
Solution Approach 1:
The system replaces complex mechanical adjustment mechanisms with automated sensor-based control. Instead of requiring manual intervention or complex mechanical systems to adjust polishing parameters, the invention uses sensors to monitor material removal rates and automatically controls polishing parameters through software algorithms, simplifying the overall system while improving precision.
3Manufacturing precision
If polishing parameters are adjusted in real-time to compensate for regional differences, then surface uniformity is improved, but processing time increases
Solution Approach 1:
The real-time monitoring and adjustment process operates continuously during the polishing operation without requiring interruptions or separate calibration steps. The system measures material removal rates and adjusts parameters on-the-fly, maintaining continuous polishing action while ensuring uniform surfaces, thereby minimizing additional processing time.
Data Source
AI summary
Systems and methods are provided for controlling a polishing process in real-time. First and second characteristics are identified in first and second data sets, respectively, with each data set corresponding to a real-time wafer polishing data. A time delta is computed between the times at which the first and second characteristics occur within their respective data sets, and polishing parameters are then updated in real-time based on the computed time delta.