Exposure Apparatus Focus Leveling for Incomplete Shot Areas
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Solution Overview
Problem
Existing exposure apparatuses face challenges in accurately controlling the surface position of substrates, particularly near the outer edges, due to varying curvature and inclination, leading to increased defocus errors during semiconductor device manufacturing.
Innovation Solution
The exposure apparatus performs focus measurement up to the outer edge of the substrate and determines an approximate plane for incomplete shot areas, using a focus-leveling value to control the surface position, thereby minimizing defocus and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If focus measurement is performed only within the pattern forming area, then the control system remains simple, but surface position control accuracy deteriorates at incomplete shot areas near the outer edge
Solution Approach 1:
The system performs focus measurement in advance across the entire substrate surface including incomplete shot areas before exposure. This preliminary measurement allows the control system to determine appropriate focus-leveling values for all regions, ensuring accurate surface position control even at areas that will not receive exposure patterns.
Solution Approach 2:
The substrate surface is divided into multiple measurement regions including complete shot areas and incomplete shot areas. The system independently determines focus-leveling values for each region based on local surface characteristics, allowing optimized control for each segment rather than applying a uniform approach across the entire substrate.
2Measurement precision
If focus measurement extends to the outer edge of the substrate, then surface position control accuracy improves, but measurement time and processing complexity increase
Solution Approach 1:
The system applies different measurement and control strategies to different regions of the substrate. Complete shot areas use standard focus control, while incomplete shot areas near the outer edge use specialized focus-leveling based on locally determined surface positions. This localized approach ensures high accuracy where needed without uniformly increasing measurement complexity across the entire substrate.
3Manufacturing precision
If a single plane approximation is used for focus control, then the control process remains simple, but defocus errors increase in areas with varying curvature and inclination
Solution Approach 1:
The focus control system dynamically adjusts focus-leveling values based on the specific characteristics of each shot area. Rather than applying a static single-plane approximation, the system determines appropriate focus adjustments for complete shot areas and incomplete shot areas separately, adapting the control parameters to local surface geometry and exposure requirements.
Data Source
AI summary
According to one embodiment, there is provided an exposure apparatus, including a focus detecting system, a stage, and a controller. On the stage, a substrate is to be mounted. The controller performs focus measurement on an incomplete shot area, part of which is outside a pattern forming area of the substrate, by the focus detecting system. The controller obtains amounts of defocus of a plurality of planes that are candidates for approximating the incomplete shot area according to the result of measuring the incomplete shot area. The controller decides on a plane to approximate the incomplete shot area from among the plurality of planes according to the amounts of defocus of the plurality of planes. The controller drives the stage using a focus-leveling value according to the decided-on plane so as to control a surface position of the incomplete shot area.