Exposure Apparatus Stage Control for Focus Error Correction
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Solution Overview
Problem
In exposure apparatuses for semiconductor devices, the deformation of frame structures due to substrate stage acceleration or deceleration leads to errors in focus measurement, making it difficult to accurately transfer the pattern of a mask onto a substrate, and unexposed shot regions may occur due to unsatisfied exposure conditions.
Innovation Solution
The exposure apparatus drives the substrate stage in accordance with pre-obtained drive information to correct focus measurement errors and ensures exposure of unexposed shot regions by re-driving the stage with the same drive information used during initial exposure, maintaining consistent exposure conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the substrate stage is accelerated or decelerated during exposure, then the exposure process can be completed efficiently, but the frame structure deforms causing focus measurement errors
Solution Approach 1:
The system performs preliminary focus measurement during constant-speed movement before acceleration occurs, and pre-calculates correction values for the upcoming acceleration phase. This allows the focus measurement to be taken when the frame structure is stable, avoiding deformation errors during acceleration while still enabling efficient exposure completion.
Solution Approach 2:
The system continuously monitors the substrate stage acceleration and uses this feedback to dynamically adjust focus measurement timing and apply correction values. By detecting acceleration events and responding with appropriate correction actions, the system maintains focus accuracy despite frame deformation during stage movement.
2Productivity
If the exposure condition is not satisfied for a shot region, then the substrate stage moves to the next region, but unexposed regions reduce yield
Solution Approach 1:
The system monitors exposure conditions for each shot region and uses this feedback to determine whether re-exposure is needed. When an unexposed region is detected, the system triggers a re-exposure sequence while maintaining the same drive information to ensure consistent focus conditions, thereby improving yield without compromising exposure quality.
Solution Approach 2:
The system checks exposure condition satisfaction in advance and prepares re-exposure sequences proactively. By identifying unexposed regions before finalizing the exposure process, the system can schedule re-exposure operations efficiently, ensuring complete coverage while maintaining productivity.
3Reliability
If the substrate stage is re-driven to expose unexposed regions, then yield increases, but exposure condition consistency must be maintained
Solution Approach 1:
The system copies the original drive information used during initial exposure and applies it again during re-exposure of unexposed regions. This ensures that the same acceleration profile and timing conditions are reproduced, maintaining focus measurement consistency and exposure quality without requiring complex adaptive control algorithms.
Data Source
AI summary
The present invention provides an exposure apparatus which exposes each of a plurality of shot regions on a substrate, comprising a substrate stage configured to be movable while holding the substrate, and a control unit, wherein the plurality of shot regions include a first shot region, and a second shot region which is exposed next to the first shot region, and the control unit drives the substrate stage in accordance with drive information of the substrate stage in a period until exposure of the second shot region starts after an end of exposing the first shot region, and when an exposure condition for exposing the second shot region is not satisfied in the period, the control unit drives again the substrate stage in accordance with the drive information and then exposes the second shot region.