Multi-Mask Exposure Apparatus Continuous Scanning
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Solution Overview
Problem
Current exposure apparatuses for semiconductor processing face limitations in throughput due to the need for high speeds and accelerations of wafers and reticles, which is challenging to achieve without compromising precision and efficiency.
Innovation Solution
The exposure apparatus utilizes multiple masks to transfer images to a substrate, allowing for sequential exposure of adjacent sites without stopping or changing the substrate's movement direction, thereby increasing throughput by eliminating the need for stepping motions and optimizing illumination beam polarization for each mask pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the wafer and reticle are moved at higher speeds and accelerations to increase throughput, then the number of exposures per hour increases, but it becomes difficult to maintain precision and operational stability
Solution Approach 1:
The patent implements continuous scanning exposure where the substrate stage moves continuously through multiple sites without stopping or reversing direction. The illumination system continuously exposes patterns across the substrate as it moves, eliminating the start-stop-cycling motion of traditional steppers. This continuous operation maintains constant velocity, avoiding acceleration/deceleration cycles that compromise precision while maximizing throughput.
Solution Approach 2:
The patent divides the exposure process into multiple independent pattern beams (first pattern beam, second pattern beam, etc.) that can be generated simultaneously from different masks. Each pattern beam is directed to different sites on the substrate, allowing parallel exposure of multiple locations. This segmentation enables the system to process multiple sites concurrently during continuous motion, increasing throughput without requiring higher speeds.
2Productivity
If traditional stepper or scanner systems are used with single masks, then the system is simpler to operate, but the throughput is limited by the need for stepping motions and direction changes
Solution Approach 1:
The patent combines multiple masks (first mask, second mask, etc.) and multiple illumination sources into a single integrated exposure system. All masks are positioned on the substrate stage together, and multiple pattern beams are generated and directed simultaneously onto different sites of the same substrate. This merging eliminates the need for separate exposure cycles for different patterns, allowing continuous scanning through all sites in one pass, thereby increasing throughput despite the added complexity of multiple masks.
3Productivity
If the substrate is moved at constant velocity through multiple sites, then the number of stepping motions is reduced and throughput increases, but multiple masks and pattern beams are required
Solution Approach 1:
The patent makes the substrate stage universally capable of holding and moving multiple different masks (first mask, second mask, etc.) and multiple substrates simultaneously. The illumination system is designed to generate multiple pattern beams from different masks and direct them to different sites on the same substrate or different substrates. This multi-functionality allows the system to handle diverse exposure requirements in a single continuous scanning operation, increasing throughput without requiring separate machines for different patterns.
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 enhances overall throughput by enabling continuous scanning of multiple sites at constant velocity, reducing the number of stepping motions and improving exposure efficiency, thus increasing the number of exposures per hour.
Implementation Method 1
an optical assembly, a wafer stage assembly that positions a semiconductor wafer, a measurement system, and a control system
Implementation Method 2
The optical assembly directs and focuses the first pattern beam and the second pattern beam onto the substrate
Data Source
AI summary
An exposure apparatus (10) for transferring a first mask pattern (29A) from a first mask (26A) and a second mask pattern (29B) from a second mask (26B) to a substrate (28) includes a first mask stage assembly (18A), a second mask stage assembly (18B), an illumination system (14A), a substrate stage assembly (20), and an optical assembly (16). The first mask stage assembly (18A) positions the first mask (26A). The second mask stage assembly (18B) positions the second mask (26B). The illumination system (14A) selectively generates a first illumination beam (32A) that is directed at the first mask (26A) to generate a first pattern beam (38A), and a second illumination beam (32B) that is directed at the second mask (26B) to generate a second pattern beam (38B). The substrate stage assembly (20) positions the substrate (28). The optical assembly (16) can include a first optical inlet (40A) that receives the first pattern beam (38A), a spaced apart second optical inlet (40B) that receives the second pattern beam (38B), and an optical outlet (40C) that directs and focuses the first pattern beam (38A) and the second pattern beam (38B) onto the substrate (28).