Wafer Mark Measurement Layout for Overlay Accuracy and Throughput
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Solution Overview
Problem
The increasing demand for higher overlay accuracy in micro-device manufacturing due to finer integrated circuits poses challenges in correcting wafer distortions caused by processing steps like resist coating, developing, etching, and CMP, which existing exposure apparatuses struggle to address effectively.
Innovation Solution
A measurement system comprising multiple measurement devices and a carrying system that acquires and processes position information on marks on substrates, allowing for concurrent measurement and processing across different stages of substrate processing, including cleaning, oxidation/diffusion, film deposition, and etching, to enhance alignment accuracy and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of sample shot areas in wafer alignment is increased to improve overlay accuracy, then measurement precision is improved, but device complexity increases due to the need for multiple measurement devices and concurrent processing
Solution Approach 1:
The system divides the measurement function into multiple specialized measurement devices, each handling specific shot areas or substrate types. This segmentation allows each device to be optimized for its specific task while collectively providing comprehensive coverage for high-precision overlay measurement across the entire wafer surface
Solution Approach 2:
The measurement system is designed with multi-functional capabilities where measurement devices can handle different substrate types (wafers with different processing stages) and different shot area configurations. The system provides universal measurement functionality across various manufacturing conditions while maintaining high precision through specialized measurement modes
2Measurement precision
If multiple measurement devices are used to increase the number of sample shot areas, then measurement precision is improved, but productivity decreases due to the complexity of coordinating multiple devices
Solution Approach 1:
The system implements continuous measurement operations where multiple measurement devices operate simultaneously and concurrently process different substrates or different shot areas. This parallel processing eliminates idle time between measurements and maintains continuous productive action across the entire measurement system
Solution Approach 2:
The system performs preliminary measurements on substrates at different processing stages (after resist coating, after etching, after CMP) before final exposure. This preliminary action allows distortion correction to be applied in advance, improving overlay accuracy without adding time to the critical exposure path
3Manufacturing precision
If wafer distortion correction is performed to improve overlay accuracy, then manufacturing precision is improved, but measurement precision deteriorates due to distortion in mark arrangement
Solution Approach 1:
The system performs measurements on substrates at multiple processing stages, capturing mark positions before significant distortion occurs. By measuring early in the process chain and tracking distortion progression, the system can separate true mark position information from process-induced distortion, maintaining measurement precision while enabling accurate correction
Solution Approach 2:
The system implements feedback loops where measurement data from multiple devices and multiple processing stages is continuously analyzed and used to refine distortion correction models. This feedback mechanism allows the system to learn and adapt to distortion patterns, improving both measurement accuracy and correction effectiveness over time
Data Source
AI summary
A measurement system used in a manufacturing line for micro-devices includes: a plurality of measurement devices in which each device performs measurement processing on a substrate; and a carrying system to perform delivery of a substrate with the plurality of measurement devices. The plurality of measurement devices includes a first measurement device that acquires position information on a plurality of marks formed on a substrate, and a second measurement device that acquires position information on a plurality of marks formed on a substrate. Position information on a plurality of marks formed on a substrate can be acquired under a setting of a first predetermined condition in the first measurement device, and position information on a plurality of marks formed on another substrate can be acquired under a setting of a second predetermined condition different from the first predetermined condition in the second measurement device.