Monitor Wafer Alignment Using Product Wafer Reference Marks
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Solution Overview
Problem
The accuracy of a monitor wafer at the measuring position inside a semiconductor manufacturing apparatus is low, making it difficult to monitor machine performance effectively during the semiconductor process.
Innovation Solution
A method and apparatus where a product wafer with alignment marks is used as a reference to align and position a monitor wafer, ensuring that the projection of the monitor wafer coincides with the product wafer in a vertical direction, allowing for accurate measurement by determining the product measuring sites based on these marks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the monitor wafer is moved directly by the moving unit without alignment marks, then the measuring process is simplified, but the measurement precision deteriorates due to movement errors of hundreds of micrometers
Solution Approach 1:
The patent introduces alignment marks as an intermediary element between the monitor wafer and the measuring apparatus. These marks serve as reference points that mediate the positioning process, allowing the system to compensate for moving unit errors without requiring complex real-time correction mechanisms. The alignment marks act as a bridge that translates rough mechanical positioning into precise measurement locations.
Solution Approach 2:
The patent applies preliminary action by pre-defining alignment marks on the monitor wafer before the measurement process. These marks are prepared in advance to establish reference positions that will be used during measurement. By pre-establishing these reference points, the system can compensate for positioning errors without requiring complex real-time correction mechanisms during the actual measurement.
2Measurement precision
If alignment marks are added to the monitor wafer, then the measurement precision is improved through error compensation, but the device complexity increases due to additional marking and identification requirements
Solution Approach 1:
The patent uses the product wafer as a copy or reference model for positioning the monitor wafer. By aligning the monitor wafer with the product wafer using alignment marks, the system transfers the precise positioning information from the product wafer to the monitor wafer. This copying approach allows error compensation without requiring complex dedicated positioning systems for the monitor wafer.
Solution Approach 2:
The alignment marks serve multiple functions: they are used for both aligning the monitor wafer with the product wafer and for compensating moving unit errors. This multi-functionality reduces the need for separate positioning systems and simplifies the overall device complexity while maintaining high measurement precision.
3Ease of operation
If the monitor wafer is positioned using only the conveying structure and moving unit, then the ease of operation is maintained, but the manufacturing precision deteriorates due to accumulated positioning errors
Solution Approach 1:
The monitor wafer performs self-alignment by using its own alignment marks as reference points. The alignment marks on the monitor wafer enable it to self-correct positioning errors by providing reference information that the measuring apparatus can use to compensate for moving unit inaccuracies. This self-service approach maintains ease of operation while improving positioning precision.
Data Source
AI summary
The present invention relates to a monitor wafer measuring method and measuring apparatus. The monitor wafer measuring method comprises the following steps: fixing a product wafer, the product wafer having several alignment marks and product measuring sites corresponding respectively to the alignment marks; determining the product measuring sites according to the alignment marks; and placing a monitor wafer, a projection of the monitor wafer in a vertical direction being aligned with and coinciding with the product wafer. The present application can reduce or even eliminate positional errors of the monitor wafer during a measurement process, such that product-level measuring position accuracy can be achieved for the monitor wafer and further, the measuring machine itself and process changes can be monitored in a better way.