Multi-Column Overlay Metrology for High-Throughput Sampling
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Solution Overview
Problem
Current optical metrology systems face challenges in achieving sub-nanometer overlay accuracy and high throughput for semiconductor fabrication due to limitations in wavelength and the increasing demand for tighter overlay tolerances, requiring more efficient and accurate metrology methods.
Innovation Solution
A multi-column metrology tool with multiple measurement columns that simultaneously probe multiple regions on a sample, each equipped with an illumination subsystem, a collection subsystem, and a column-positioning system, allowing for independent positioning and alignment of metrology targets within the measurement fields, enabling high-throughput sampling and accurate overlay measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If optical metrology is used to increase throughput, then measurement speed is improved, but measurement precision deteriorates due to wavelength limitations
Solution Approach 1:
The system divides the measurement task into multiple independent measurement columns (first, second, third columns) that simultaneously measure different regions of the sample. This segmentation allows the system to achieve high throughput by parallelizing measurements while maintaining precision through multiple independent measurement channels that can be processed to achieve sub-nanometer overlay accuracy.
Solution Approach 2:
The patent transitions from single-column sequential measurement to multi-column simultaneous measurement, adding a spatial dimension to the measurement architecture. Multiple measurement columns are positioned at different locations (first position, second position, third position) to probe different measurement regions concurrently, effectively using spatial parallelism to resolve the throughput-precision tradeoff.
2Measurement precision
If tighter overlay tolerances are required, then measurement accuracy is improved, but the number of targets and measurement complexity increases
Solution Approach 1:
The measurement system is segmented into multiple independent measurement columns, each capable of measuring specific targets. This allows the system to handle complex measurement requirements by distributing the measurement load across multiple columns rather than requiring a single complex measurement path, thereby managing complexity while achieving tight overlay tolerances.
Solution Approach 2:
The system employs dynamic positioning capabilities where measurement columns can be selectively activated and positioned based on which measurement regions require probing. This dynamic allocation of measurement resources allows the system to adapt to different measurement scenarios and maintain precision without permanently configuring all possible measurement paths, thus managing device 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 multi-column metrology tool provides enhanced accuracy and throughput by allowing simultaneous measurement of multiple targets across a sample, addressing the need for tighter overlay tolerances and increased feature density in semiconductor devices.
Implementation Method 1
an illumination sub-system to direct illumination from at least one of one or more illumination sources to the sample
Implementation Method 2
a collection sub-system including a collection lens to collect measurement signals from the sample and direct the measurement signals to one or more detectors
Data Source
AI summary
A multi-column metrology tool may include two or more measurement columns distributed along a column direction, where the two or more measurement columns simultaneously probe two or more measurement regions on a sample including metrology targets. A measurement column may include an illumination sub-system to direct illumination to the sample, a collection sub-system including a collection lens to collect measurement signals from the sample and direct it to one or more detectors, and a column-positioning sub-system to adjust a position of the collection lens. A measurement region of a measurement column may be defined by a field of view of the collection lens and a range of the positioning system in the lateral plane. The tool may further include a sample-positioning sub-system to scan the sample along a scan path different than the column direction to position metrology targets within the measurement regions of the measurement columns for measurements.