Parallel Metrology Sensor Array for Lithography Alignment
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Solution Overview
Problem
Current metrology sensors in lithographic apparatuses are limited in their ability to measure multiple alignment marks quickly, leading to inefficiencies in capturing higher-order distortions and affecting throughput, as they are typically of a single-sensor head design that is large, expensive, and difficult to position efficiently.
Innovation Solution
A parallel metrology sensor system utilizing a plurality of integrated optics sensor heads arranged in an array, each capable of independent measurement, with a reference frame and actuation mechanisms to accommodate varying field sizes and precise positioning, enabling the measurement of numerous alignment marks without significant increases in measurement time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single-sensor head design is used, then the device is simpler in structure, but the measurement speed and number of alignment marks measured per wafer are limited
Solution Approach 1:
The metrology sensor system is divided into multiple independent sensor heads (first sensor head, second sensor head, etc.) that can simultaneously measure different alignment marks. Each sensor head operates independently with its own optical path and detection system, enabling parallel measurement of multiple alignment marks across the wafer surface, thereby increasing productivity without requiring a completely new system architecture
2Measurement precision
If more sensor heads are added to measure more alignment marks, then the measurement coverage increases, but the device complexity and positioning difficulty increase
Solution Approach 1:
Multiple sensor heads share common functional components including the wafer stage, reference frame, and control system. Each sensor head is designed with the same optical path structure and measurement capability, allowing them to perform identical functions at different positions. This universal design simplifies the overall system complexity while enabling comprehensive measurement coverage across the entire wafer surface
Solution Approach 2:
Additional sensor heads are created as copies of the first sensor head, each capable of performing the same measurement function. The sensor heads are substantially identical in structure and operation, with the primary difference being their spatial arrangement and which alignment marks they measure. This copying approach maintains measurement precision while scaling up the system capability
3Productivity
If a single-sensor head design is used, then the device is easier to manufacture, but the measurement time increases and throughput is reduced
Solution Approach 1:
The sensor heads are pre-positioned and pre-aligned relative to each other and to the wafer stage before measurement begins. The reference frame is established in advance, and the spatial relationships between sensor heads are fixed during assembly. This preliminary configuration allows the system to achieve high throughput during operation without requiring complex real-time positioning adjustments, thereby improving manufacturability
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 allows for the efficient measurement of over 200 to 500 alignment marks per wafer, maintaining throughput while capturing more detailed wafer deformations, thereby improving overlay performance and accuracy.
Implementation Method 1
a first plurality of integrated optics sensor heads in a first column of the array, the first plurality of integrated optics sensor heads being spaced apart in a first direction parallel to the substrate plane
Data Source
AI summary
Disclosed is a parallel metrology sensor system comprising a reference frame and a plurality of integrated optics sensor heads, each integrated optics sensor head configured to perform an independent measurement. Each of the integrated optics sensor heads is operable to measure its position with respect to the reference frame.