CMP Substrate Orientation Sensing for Precise Endpoint Analysis
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Solution Overview
Problem
Conventional CMP operations cannot determine the rotational orientation of the substrate relative to the carrier head during the endpoint analysis, leading to uncertainties in the polishing process.
Innovation Solution
A method and system that includes an orientation sensor embedded in the platen at the rotational center to scan the edge of the substrate, allowing for the determination of a reference mark to establish the rotational orientation of the substrate relative to the carrier head, and endpoint sensors to monitor the polishing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional CMP operations are used without orientation sensing, then the polishing process can proceed, but the rotational orientation of the substrate relative to the carrier head cannot be determined during endpoint analysis
Solution Approach 1:
An orientation sensor is introduced as an intermediary device between the substrate and the measurement system. The sensor detects the rotational orientation of the substrate by sensing the position of features on the substrate edge, providing orientation information that mediates between the physical substrate state and the endpoint analysis system, enabling precise correlation of polishing depth with specific substrate locations
Solution Approach 2:
The patent replaces mechanical orientation marking methods with an optical/electromagnetic sensing system. Instead of using physical markers or mechanical alignment features, the orientation sensor uses optical or electromagnetic fields to detect substrate orientation non-contactly, eliminating mechanical interference and providing more precise measurement capability
2Productivity
If the substrate rotational orientation is unknown during polishing, then the polishing process can continue, but the correlation between endpoint sensor readings and specific substrate locations cannot be established
Solution Approach 1:
The orientation sensor provides continuous feedback about the substrate's rotational orientation during the polishing process. This feedback is fed back to the control system, which uses it to correlate endpoint sensor readings with specific substrate locations in real-time, enabling location-specific process control and precise endpoint detection without interrupting the polishing operation
Solution Approach 2:
The system performs preliminary orientation detection by scanning the substrate edge before the main polishing operation begins. This preliminary action establishes the initial rotational orientation reference, allowing the system to track and maintain orientation information throughout the subsequent polishing process, ensuring that endpoint readings can be accurately correlated with substrate locations from the start
Data Source
AI summary
A method of processing a substrate includes polishing a front surface of a substrate on a first pad coupled to a first platen. The method further includes transferring the substrate from the first pad to a second pad coupled to a second platen with a carrier head. The method further includes moving the carrier head to a scan position to place an edge of the substrate above an orientation sensor disposed at a rotational center of the second pad. The method further includes scanning the edge of the substrate with the orientation sensor to produce a signal. The method further includes analyzing the signal to locate a reference mark of the substrate to determine a rotational orientation of the substrate relative to the carrier head.