Real-Time Lithography Registration With Shared Alignment Optics
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Solution Overview
Problem
Current Direct Imaging (DI) and Laser Direct Imaging (LDI) lithography systems face limitations in throughput and accuracy due to time-consuming registration and measurement of reference points, especially when dealing with high precision and fine line/space requirements, which are exacerbated by the need for separate opto-mechanical systems for measurement and lithography.
Innovation Solution
A device and method that integrates a light source, light modulator, and measurement system with concurrent optical paths, using a camera to measure alignment marks in real-time, sharing the same opto-mechanical structure as the exposure system, and transferring data directly to a FPGA for fast pattern calculation and printing, optimizing camera data transfer by defining a camera area of interest.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of reference points/fiducials is increased to achieve higher measurement accuracy for fine line lithography, then measurement precision is improved, but the time consumption for measurements increases significantly
Solution Approach 1:
The patent combines the measurement function and exposure function into a single integrated lithography system. The measurement unit (camera) and exposure unit (projector) share the same opto-mechanical platform, allowing simultaneous or overlapping operation. This merging eliminates the sequential bottleneck where measurement must complete before exposure, enabling parallel processing that reduces total time while maintaining high accuracy through multiple reference points
Solution Approach 2:
The system enables continuous operation by allowing the measurement unit to capture reference points while the exposure unit is printing or preparing to print. The real-time data transfer and processing pipeline ensures that measurement data is continuously fed into the pattern calculation engine without interruption. This continuous workflow eliminates idle time between measurement and exposure operations, maintaining high productivity even with increased measurement complexity
2Adaptability or versatility
If separate opto-mechanical systems are used for measurement and lithography, then each system can be optimized independently, but the complexity of the overall system increases and calibration uncertainty affects yield
Solution Approach 1:
The patent integrates the measurement unit and exposure unit into a single shared opto-mechanical system. Both the camera (measurement) and projector (exposure) are mounted on the same mechanical platform and share common optical components, motion stages, and control systems. This unified architecture reduces the number of separate systems from two to one, eliminating the need for complex inter-system calibration while maintaining the ability to optimize measurement and exposure functions within the shared platform
Solution Approach 2:
The shared opto-mechanical system is designed to perform multiple functions: the camera captures reference points for measurement, the projector delivers exposure patterns, and both operations can occur simultaneously or in overlapping sequences on the same substrate. This multi-functional design allows a single system to replace what would traditionally require two separate specialized systems, reducing overall complexity while maintaining versatility for both high-precision measurement and lithographic exposure
3Productivity
If real-time data transfer and pattern calculation is implemented, then throughput is improved, but the requirement for sophisticated calibration and data processing increases system complexity
Solution Approach 1:
The patent replaces traditional mechanical data transfer methods (physical media, manual input) with direct digital data transfer between the measurement unit's camera and the exposure unit's pattern calculation engine. The camera outputs digital coordinates that are immediately fed into the FPGA or video processor for real-time pattern warping calculations. This electronic substitution eliminates data transfer bottlenecks and enables sub-millisecond processing speeds, achieving high throughput while the standardized digital interface keeps processing complexity manageable
Solution Approach 2:
The system dynamically adjusts processing parameters based on real-time measurement data. The pattern calculation engine receives measured reference point coordinates and automatically computes the transformation parameters (translation, rotation, scaling, warping) needed to align the exposure pattern with the substrate. This automated parameter adjustment replaces manual calibration procedures and enables real-time adaptation to substrate variations, maintaining high throughput through efficient algorithmic processing rather than complex mechanical adjustments
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 significantly reduces the time consumption of high-accuracy measurements, enhancing throughput and precision in fine line lithography by allowing real-time registration and pattern warping, thereby improving the overall efficiency and accuracy of the lithography process.
Implementation Method 1
a camera, and where the measurement system is configured to measure a position of a number of alignment marks previously patterned on a substrate
Implementation Method 2
a light modulator modulating the exposure beam according to an exposure pattern
Data Source
Figure 1
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Figure 1b
AI summary
A device for measuring reference points in real time during lithographic printing comprises a light source providing an exposure beam, a light modulator modulating the exposure beam according to an exposure pattern, a measurement system configured to measure a position of a number of alignment marks previously arranged on a substrate, and an exposure optical system comprising a control unit. The exposure optical system delivers the modulated exposure beam as an image provided by the light modulator onto the substrate and the exposure system control unit is configured to calculate the orientation of the substrate based on the position of the alignment marks and control the delivering of the modulated exposure beam relative to the calculated orientation of the substrate.