Digital Lithography Metrology for Small-Mark Overlay Alignment
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Solution Overview
Problem
Existing digital lithography systems face challenges in achieving accurate overlay alignment and die placement for small alignment and die marks, which are crucial for advanced semiconductor and display device manufacturing.
Innovation Solution
A metrology system integrated with the digital lithography system, comprising a microscope body, lens, focusing stage, LEDs, and illuminators, is used to capture and analyze images of alignment and die marks, enabling precise position determination and digital correction for improved overlay alignment and die placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional digital lithography systems are used for aligning subsequent layers, then the basic lithography process can be performed, but overlay alignment accuracy deteriorates when dealing with small alignment marks and die marks (width less than 50 um)
Solution Approach 1:
The system separates the metrology function from the lithography function by integrating a dedicated metrology system with microscope body, objective lens, and camera specifically for mark detection, while the lithography system handles pattern formation. This segmentation allows each subsystem to be optimized for its specific function, enabling precise detection of small alignment marks without compromising lithography performance.
Solution Approach 2:
The integrated metrology system acts as an intermediary between the lithography system and the alignment marks. It captures images of the marks, determines their positions, and provides correction data that is then used by the lithography system to improve overlay alignment accuracy for subsequent layers.
2Productivity
If small alignment marks and die marks are used to enable higher integration, then device integration density increases, but measurement and detection difficulty increases
Solution Approach 1:
The metrology system employs an objective lens with specific optical properties optimized for detecting small features. The system provides localized high-quality imaging capability for mark detection, allowing precise measurement of sub-50um alignment marks and die marks necessary for high-density integration without requiring the entire lithography system to be redesigned.
3Manufacturing precision
If a dedicated metrology system is integrated to improve alignment accuracy, then overlay alignment accuracy improves, but device complexity increases
Solution Approach 1:
The metrology system is physically integrated with the lithography system, combining mark detection, position determination, and correction functions into a unified platform. This merging allows the system to perform both lithography and precise metrology without requiring completely separate systems, thereby improving overlay alignment accuracy while limiting the increase in overall system complexity.
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
The system enhances overlay alignment accuracy and die placement precision, increasing yield and enabling higher integration of 2D and 3D packages by correcting errors in situ, thus improving process stability and alignment resolution.
Implementation Method 1
a first LED, a second LED, and a third LED coupled to the microscope body. The LEDs deliver light to the microscope body
Implementation Method 2
a lens coupled to the microscope body, and a focusing stage disposed between the microscope body and the lens
Implementation Method 3
The focusing stage is configured to move the lens to adjust a focus of the lens
Implementation Method 4
an illuminator disposed below the lens
Data Source
AI summary
Systems and methods disclosed herein relate to a digital lithography system and method for alignment resolution with the digital lithography system. The digital lithography system includes a metrology system configured to improve overlay alignment for different layers of the lithography process. The metrology system allows for decreased size of alignment marks. Based on determining the positions of alignment marks with the metrology system, correction data is obtained to achieve accurate overlay of layers on subsequent patterning processes.