Exposure Apparatus Substrate Stage Position Control
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Solution Overview
Problem
The challenge in the lithographic process for semiconductor manufacturing is achieving accurate alignment of the substrate surface with the image plane, particularly with decreasing depth of focus and increasing substrate surface variance, which leads to focus sampling errors and increased manufacturing complexity due to the need for precise surface position measurement.
Innovation Solution
An exposure apparatus with a projection optical system, a substrate stage, a console for setting valid measurement areas, and a controller to adjust the substrate position based on measured surface data, using a multi-point surface position measuring device to ensure accurate alignment and reduce focus sampling errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple measurement points are provided before and after the exposure slit to measure substrate surface position, then measurement coverage is improved, but device complexity increases
Solution Approach 1:
The patent pre-calculates the optimal number and positions of measurement points based on the depth of focus and shot region dimensions before exposure begins. This preliminary determination allows the system to use only the necessary minimum number of measurement points, avoiding unnecessary complexity while ensuring adequate measurement coverage for accurate focus control
Solution Approach 2:
The system dynamically adjusts the number and positioning of measurement points as parameters based on the specific exposure conditions, including the depth of focus, shot region size, and substrate characteristics. This parameter-based configuration optimizes the measurement system for each exposure scenario without requiring a fixed complex multi-point system for all cases
2Productivity
If the exposure area is increased to improve productivity, then manufacturing efficiency is improved, but focus control difficulty increases due to larger substrate surface variance
Solution Approach 1:
Before exposure, the system pre-determines the optimal measurement point configuration based on the shot region dimensions and expected substrate surface variance. This preliminary setup ensures that adequate measurement coverage is established across the entire exposure area, enabling accurate focus control even for large-area exposures
Solution Approach 2:
The patent extends measurement coverage from a single line to a two-dimensional grid pattern across the shot region. By distributing measurement points in both the scanning direction and the direction perpendicular to scanning, the system achieves comprehensive substrate surface characterization across large exposure areas, maintaining focus accuracy despite increased area
3Manufacturing precision
If measurement points are positioned at specific locations to reduce focus sampling error, then focus accuracy is improved, but the requirement for precise measurement point positioning increases device complexity
Solution Approach 1:
The system determines measurement point positions as calculated parameters based on exposure conditions rather than requiring fixed precise mechanical positioning. The number and locations of measurement points are derived from parameters such as depth of focus, shot region size, and substrate characteristics, allowing flexible adaptation without stringent mechanical tolerances
Solution Approach 2:
The measurement point configuration is made dynamic and adaptable to different exposure scenarios. Rather than requiring fixed precise positioning for all cases, the system adjusts the number and positions of measurement points based on real-time parameters including the specific shot region geometry and substrate surface characteristics, reducing the burden of precise mechanical positioning
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 solution enables precise alignment of the substrate surface with the image plane, improving focus accuracy and reducing manufacturing complexity by determining valid measurement points and adjusting the substrate position accordingly, thus enhancing the yield and efficiency of semiconductor device production.
Implementation Method 1
a gap sensor such as an oblique-incident-light surface position measuring device
Data Source
AI summary
An exposure apparatus includes a projection optical system for projecting light from a reticle onto a substrate, and exposes a shot region of the substrate to radiant energy via the reticle and the projection optical system. The exposure apparatus comprises a substrate stage configured to hold the substrate and to be moved, a console configured to set a valid area inside the shot region, a measuring device configured to measure a position of a surface of the substrate in a direction parallel to an optical axis of the projection optical system, and a controller configured to control a position of the substrate stage based on the position of the surface measured by the measuring device at a measurement point in the valid area set by the console, the measurement point being determined in accordance with a position of the substrate relative to the measuring device.