Rotating Thermal Sensor for CMP Pad Temperature Control
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Solution Overview
Problem
Chemical mechanical polishing (CMP) processes face challenges in maintaining temperature uniformity across the polishing pad, leading to variations in removal rate, polishing uniformity, erosion, and residue due to temperature-dependent chemical and mechanical variables.
Innovation Solution
A temperature monitoring system with a non-contact thermal sensor that rotates to sweep across the polishing pad, generating a temperature profile and controlling a heating or cooling system to adjust temperature uniformly, ensuring improved temperature control without requiring lateral translation of the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a non-contact thermal sensor is used to monitor temperature, then measurement precision is improved, but device complexity increases due to the need for rotation mechanisms and control systems
Solution Approach 1:
The thermal sensor is made rotatable to dynamically sweep across the polishing pad surface, enabling temperature measurement at multiple radial positions without requiring lateral translation of the sensor itself. This dynamic positioning allows a single sensor to monitor the entire pad surface, improving measurement coverage and precision while managing device complexity through controlled rotation rather than multiple fixed sensors
Solution Approach 2:
The sensor rotation adds a temporal dimension to the measurement process, where measurements are taken at different angular positions around the polishing pad. This transforms a single-point spatial measurement into a comprehensive surface profile measurement by accumulating data across multiple angular positions, effectively mapping the temperature distribution across the pad surface
2Manufacturing precision
If temperature control is implemented to improve polishing uniformity, then manufacturing precision is improved, but device complexity increases due to additional heating/cooling systems
Solution Approach 1:
The temperature monitoring system provides real-time feedback on the polishing pad temperature distribution, enabling the control system to adjust heating or cooling elements accordingly. This closed-loop feedback control ensures temperature uniformity across the pad surface, improving polishing manufacturing precision by compensating for temperature variations that would otherwise affect removal rate and surface quality
Solution Approach 2:
The system changes the temperature parameter of the polishing pad by applying localized heating or cooling based on the measured temperature profile. By adjusting the temperature distribution across the pad surface, the system optimizes polishing uniformity and removes the harmful effect of temperature-induced variations in removal rate and surface quality
3Area of stationary object
If the sensor rotates to sweep across the polishing pad, then measurement coverage is improved, but the time required for temperature profiling increases
Solution Approach 1:
The thermal sensor rotates continuously during the polishing process, enabling temperature measurements to be taken at multiple radial positions without interrupting the polishing operation. This continuous measurement approach allows the temperature profile to be mapped in real-time, improving measurement coverage while minimizing time loss by conducting measurements concurrently with the polishing process rather than requiring separate profiling steps
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 allows for precise temperature control, reducing temperature variations and enhancing polishing performance by improving within-wafer and wafer-to-wafer uniformity, while also optimizing space usage in crowded polishing stations.
Implementation Method 1
a non-contact thermal sensor positioned above the platen that has a field of view of a portion of the polishing pad on the platen
Data Source
AI summary
A chemical mechanical polishing apparatus includes a platen having a top surface to hold a polishing pad, a carrier head to hold a substrate against a polishing surface of the polishing pad during a polishing process, and a temperature monitoring system. The temperature monitoring system includes a non-contact thermal sensor positioned above the platen that has a field of view of a portion of the polishing pad on the platen. The sensor is rotatable by the motor around an axis of rotation so as to move the field of view across the polishing pad.