Exposure Apparatus Scan Control for Mix-and-Match Overlay
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Solution Overview
Problem
The challenge lies in achieving high accuracy for mix-and-match exposure between exposure apparatuses with different projection magnifications, such as ¼ and ½ projection exposure apparatuses, due to differences in shot size and alignment, leading to superimposing errors during the lithography process in semiconductor and liquid crystal display device manufacturing.
Innovation Solution
An exposure apparatus with a controller that adjusts the scanning operation of the original and substrate holding units based on the state of the patterns formed on both the original and substrate, allowing for precise superimposition by varying the scan speed and movement trajectory to account for shot magnification and rotational errors, enabling accurate alignment across different projection magnifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mix-and-match exposure is performed between exposure apparatuses with different projection magnifications (e.g., 1/4 and 1/2 projection), then throughput is improved by exposing larger areas with single scanning, but superimposing accuracy deteriorates due to shot size differences and alignment errors
Solution Approach 1:
The patent performs preliminary measurement of the shot formed on the substrate using a measurement optical system before the actual exposure. The measured shot position and size information is stored and used to determine the scan start position and scan speed for subsequent exposure operations, enabling pre-correction of alignment errors before they occur
Solution Approach 2:
The patent implements a feedback mechanism where the measurement optical system detects the actual shot position and size, this information is fed back to the control unit, which then adjusts the scan parameters (start position, scan speed) for the exposure optical system. This closed-loop feedback continuously corrects for magnification differences and alignment errors between different projection apparatuses
2Loss of time
If shot size is increased for single scanning exposure, then exposure time is reduced and throughput is improved, but alignment error between shots increases due to larger step positions
Solution Approach 1:
The measurement optical system performs preliminary measurement of the shot position and size before exposure. This pre-measurement allows the control unit to calculate the appropriate scan start position and scan speed that will compensate for potential alignment errors, enabling larger shot sizes to be exposed with maintained precision
Solution Approach 2:
The patent dynamically adjusts scan parameters (scan start position, scan speed) based on measured shot characteristics. By changing these parameters according to the actual shot state, the system can maintain accurate alignment even when exposing larger areas with single scanning, thus reducing exposure time without sacrificing precision
Data Source
AI summary
An exposure apparatus includes a controller configured to control scanning of an original holding unit and a substrate holding unit to expose a first pattern forming area onto a plurality of second pattern forming areas formed in advance on the substrate. The first pattern forming area is superimposed on the plurality of second pattern forming areas. An original may include the first pattern forming area in plural. The controller is configured to change the operation of the original holding unit or the substrate holding unit among the plurality of second pattern forming areas based on a state of the second pattern forming areas or a state of the first pattern forming areas while the first pattern forming areas are scanning-exposed onto the plurality of second pattern forming areas in a single scanning between the original holding unit and the substrate holding unit.