Semiconductor Exposure Alignment via Height-to-Position Conversion
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Solution Overview
Problem
In semiconductor device manufacturing, the increasing feature size and vertical height differences pose challenges for achieving precise positional accuracy, particularly in aligning patterns on substrates, due to limitations in vertical resolution and alignment mark detection.
Innovation Solution
An exposure method and apparatus that utilize height detection information to calculate differential position information, allowing for precise alignment and correction of positional deviations between masks and substrates, by converting height information into position information and using it for alignment adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If height detection is used to improve vertical position measurement, then vertical resolution is improved, but device complexity increases due to additional detection systems
Solution Approach 1:
The patent combines the height detection function with the existing optical detection system by using the same optical path and detection apparatus for both alignment mark detection and height measurement. This merging approach improves vertical position measurement precision without proportionally increasing device complexity, as the same hardware serves dual purposes.
Solution Approach 2:
The detection apparatus is designed to perform multiple functions: detecting alignment marks for lateral positioning and detecting height variations for vertical positioning. This multi-functionality allows the system to achieve improved measurement precision in both lateral and vertical directions using a single integrated system, thereby limiting the increase in device complexity.
2Measurement precision
If alignment marks are used for position detection, then positioning accuracy is improved, but the method becomes inadequate for substrates with large vertical height differences
Solution Approach 1:
The patent transitions from two-dimensional alignment mark detection to three-dimensional positioning by adding height detection capability. The system now measures not only lateral positions (x, y coordinates) but also vertical height (z coordinate), enabling accurate positioning on substrates with large vertical height differences or warpage by incorporating the third dimension into the detection process.
Solution Approach 2:
The system performs preliminary height detection and calculation of differential position information before the actual exposure process. By pre-calculating the positional deviations caused by height variations and compensating for them in advance, the system ensures accurate pattern alignment even on substrates with significant vertical height differences.
3Ease of manufacture
If conventional exposure methods are used, then manufacturing process is simple, but positional accuracy deteriorates due to warpage and stress-induced shifts
Solution Approach 1:
The patent implements a feedback mechanism where height detection information is used to calculate differential position information, which then feeds back into the exposure control system. This feedback loop enables real-time compensation for warpage and stress-induced positional shifts, significantly improving pattern alignment precision while maintaining manufacturing process simplicity through automated control.
Solution Approach 2:
The system changes the parameter used for alignment from solely lateral position coordinates to include vertical height information. By incorporating height parameters into the alignment calculation and using differential position information derived from height measurements, the system compensates for warpage effects and improves manufacturing precision without complicating the overall process.
Data Source
AI summary
An exposure method includes acquiring first height information through detection of a height of an upper surface of a substrate subjected to exposure; acquiring first position information through detection of a relative position between the substrate and a first mask having a first pattern to be transferred on the substrate; converting the first height information to second position information; acquiring second height information through detection of a height of the upper surface of the substrate; acquiring third position information through detection of a relative position between the substrate and a second mask having a second pattern to be transferred on the substrate; converting the second height information to fourth position information; calculating differential position information, based on difference between the second position information and the fourth position information; and aligning the second mask and the substrate, based on the third position information and the differential position information.