Lithography Stage Detection Order for Thermal Error Reduction
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Solution Overview
Problem
Temperature distributions caused by heat generated during substrate stage movement in lithography apparatuses lead to measurement errors in global alignment, affecting the accuracy of obtaining a common index for pattern transfer in semiconductor manufacturing.
Innovation Solution
The exposure apparatus determines the detection order of sample shot regions to minimize measurement errors by considering the direction of gas flow and positional relationships between measurement units, ensuring that sample shot regions closer to measurement units are detected first, thereby reducing heat application to optical paths and maintaining accurate alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the substrate stage moves quickly to increase throughput, then productivity improves, but temperature distribution occurs on the optical path causing measurement errors
Solution Approach 1:
The patent determines the detection order of sample shot regions in advance, considering the moving direction of the substrate stage and the position of measurement units. By pre-planning the detection sequence to minimize stage movement distance, the system prepares the optimal path before actual measurement, reducing heat generation from prolonged movement while maintaining measurement accuracy.
Solution Approach 2:
The patent changes the detection order parameter based on the substrate stage's moving direction and measurement unit positions. By dynamically adjusting which sample shot regions are detected first, during, or after stage movement, the system optimizes the balance between movement distance (affecting heat generation) and measurement accuracy requirements.
2Measurement precision
If the detection order is optimized to reduce stage movement distance, then measurement accuracy improves, but the complexity of determining detection order increases
Solution Approach 1:
The patent changes the detection order parameter based on the substrate stage's moving direction and measurement unit positions. By dynamically adjusting which sample shot regions are detected first, during, or after stage movement, the system optimizes the balance between movement distance (affecting heat generation) and measurement accuracy requirements.
Solution Approach 2:
The patent uses feedback from the substrate stage's actual moving direction and the fixed positions of measurement units to determine the optimal detection order. The system continuously monitors the stage position and adjusts the detection sequence accordingly, creating a closed-loop control that adapts to real-time conditions while maintaining simplicity through rule-based decision making.
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 effectively reduces measurement errors and ensures accurate global alignment, enhancing the throughput and overlay accuracy of pattern transfer on substrates by optimizing the detection order based on gas flow and measurement unit positions.
Implementation Method 1
a measurement unit (for example, an interferometer) which irradiates the side surface of the substrate stage with light and measures the position of the substrate stage based on reflected light
Implementation Method 2
If a temperature distribution occurs on an optical path of light emitted from the measurement unit due to the influence of heat generated as the movement of the substrate stage
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A lithography apparatus which forms a pattern on a substrate, comprises a stage (14) holding the substrate and being movable; a measurement unit (4) configured to irradiate a side surface of the stage with light and measure a position of the stage, a generation unit (6) configured to generate a flow of gas in a space where the stage moves, a detection unit (15) configured to detect respective positions of sample shot regions formed on the substrate, and a control unit (16) configured to determine an order of detecting the sample shot regions by the detection unit such that detection by the detection unit is performed sequentially from a sample shot region closer to the measurement unit with respect to sample shot regions located on a downstream side of the flow of the gas from a center of the substrate.