Scatterometry-Based In-Situ Dimension Control for IC Substrate Features
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Solution Overview
Problem
Current lithography methods in the IC industry face challenges in controlling the dimensions of complex IC features, particularly at critical dimensions less than 100 nm, due to limitations in controlling X, Y, and Z dimensions, and existing measurement techniques like CD-SEM are slow, expensive, and disrupt the manufacturing process.
Innovation Solution
A processing system that includes a scatterometer and a control routine to perform scatterometry measurements on test structures with gratings arranged in different directions, allowing for in-situ, non-destructive monitoring and adjustment of substrate feature dimensions, enabling precise control of etching and deposition processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If CD-SEM is used to measure substrate features, then measurement precision is improved, but productivity deteriorates due to slow throughput and wafer transport requirements
Solution Approach 1:
The patent replaces the mechanical CD-SEM measurement system with an optical scatterometry system. The scatterometer uses optical scattering patterns to measure substrate features non-destructively and in-situ, eliminating the need for mechanical wafer transport and breaking vacuum, thereby maintaining measurement precision while dramatically improving productivity
Solution Approach 2:
The patent introduces scatterometry measurements of test structures as an intermediary method to indirectly measure the substrate features. By measuring test structures with known geometries that are processed simultaneously with the actual devices, the system obtains measurement data without directly measuring the production substrates, thus avoiding productivity loss from wafer transport
2Productivity
If in-situ monitoring is implemented, then productivity is improved through real-time feedback, but device complexity increases due to additional measurement and control systems
Solution Approach 1:
The patent segments the monitoring system into separate test structures and production structures. The test structures are specifically designed to be measured by the scatterometer, while production structures continue normal fabrication. This segmentation allows in-situ monitoring without complicating the main production process
Solution Approach 2:
The patent uses test structures that are copies or replicas of the actual device features being fabricated. These test structures contain the same patterns and materials but are dedicated to measurement purposes. By copying the feature geometry into test structures, the system achieves in-situ monitoring capability without adding complexity to the production devices themselves
3Manufacturing precision
If multiple dimension control (X, Y, Z) is implemented, then manufacturing precision is improved, but measurement complexity increases requiring multiple measurement approaches
Solution Approach 1:
The patent utilizes the angular dimension of light scattering to measure multiple feature dimensions. By analyzing scattering patterns at different angles and polarizations, the system can extract information about feature width, height, and other geometric parameters from a single optical measurement, thus controlling multiple dimensions without requiring multiple separate measurement systems
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 enables rapid, cost-effective, and non-destructive monitoring of substrate feature changes, improving process control and yield by allowing real-time adjustments to maintain target dimensions, thereby enhancing the precision and efficiency of IC feature fabrication.
Implementation Method 1
A measurement processor may determine, based upon a first set of scatterometry measurements, a first change in a first dimension of a first set of substrate features along a first direction
Data Source
AI summary
An apparatus may include a processor and memory unit, including a control routine having a measurement processor to determine, based upon a first set of scatterometry measurements, a first change in a first dimension of a first set of substrate features along a first direction. The first set of substrate features may be elongated along a second direction perpendicular to the first direction. The measurement processor may be to determine, based upon a second set of scatterometry measurements, a second change in dimension of a second set of substrate features along the second direction, wherein the second set of substrate features is elongated along the first direction. The apparatus may include a control processor to generate an error signal when a figure of merit based upon the first change and the second change lies outside a target range.