Alignment Apparatus Frame Memory Concurrent Stage Movement
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Solution Overview
Problem
Conventional exposure apparatuses face challenges in increasing throughput due to the time required to capture images of alignment marks, as they cannot start the next image capturing process until the transfer of image data from the camera to the processor is completed, leading to inefficiencies in focus adjustment and alignment processing.
Innovation Solution
The alignment apparatus employs a camera with a frame memory that temporarily stores image data before transferring it to the alignment processor, allowing the next image capturing to begin as soon as the data is accumulated, even if the transfer to the processor is not complete, and enables concurrent stage movement during image data transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor accumulates images of alignment marks and transfers image data to the alignment processor before the next image capturing, then the alignment processing can be performed accurately, but the time required to capture images of alignment marks increases
Solution Approach 1:
The patent applies preliminary action by having the sensor accumulate image data in advance and store it in the camera's memory buffer before the alignment processor is ready to process it. This allows the imaging device to be prepared for the next capture cycle without waiting for the current data transfer and processing to complete, thereby reducing the overall time required to capture multiple alignment marks while maintaining measurement precision.
2Productivity
If the stage is moved to the next measurement shot position while waiting for image data transfer, then the throughput can be improved, but the alignment accuracy may be compromised due to stage movement during data processing
Solution Approach 1:
The patent implements continuity of useful action by enabling the stage to move to the next measurement shot position concurrently with the image data transfer from the sensor to the alignment processor. The sensor continues to accumulate image data during this movement, ensuring that no time is wasted and the throughput is maximized while the memory buffer ensures data integrity is maintained throughout the continuous operation.
3Measurement precision
If the resolution of the camera sensor is increased to capture more detailed images of alignment marks, then the measurement precision is improved, but the transfer time of image data increases
Solution Approach 1:
The patent uses the camera's memory buffer as an intermediary between the high-resolution sensor and the alignment processor. This buffer temporarily stores the large volume of high-resolution image data, allowing the sensor to capture detailed images without being bottlenecked by the processor's reading speed. The buffer decouples the data capture rate from the processing rate, enabling high resolution imaging without proportionally increasing the overall transfer time.
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 approach significantly reduces the time required to capture images of alignment marks, enhancing the throughput and efficiency of the alignment process by allowing for shorter intervals between image captures and improved focus measurement and alignment calculations.
Implementation Method 1
an image sensor configured to accumulate charge by photoelectric conversion
Data Source
AI summary
An alignment apparatus performs alignment of a substrate is provided. The apparatus comprises a stage that moves while holding a substrate, an imaging device that captures an image of a mark on the substrate, and a processor that obtains a position of the mark based on the image of the mark. The imaging device includes an image sensor and a storage device that stores image data obtained by the image sensor. The imaging device performs next image capturing after the image sensor performs accumulation of charge and transfer of image data to the storage device is completed. The apparatus moves the stage for next image capturing concurrently with transfer of the image data to the storage device when capturing an image of the mark using the imaging device at a plurality of positions while moving the stage.