Lithography Model Calibration via Aerial Image Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current lithography simulation models face challenges in separating optical and resist components for accurate calibration, leading to incomplete convergence and limited predictability, requiring extensive recalibration with changes in process parameters.
Innovation Solution
A method for separately calibrating optical and resist models using in-situ aerial image measurements from an image sensor array, allowing for more accurate and separable models that improve pattern transfer predictability and model-based process control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If combined calibration of optical and resist models is performed, then calibration can be completed using only resist pattern measurements, but the calibration becomes incomplete and lacks convergence with limited predictability
Solution Approach 1:
The patent divides the combined calibration process into two separate calibration stages: first calibrating the optical model using aerial image measurements, then calibrating the resist model using resist pattern measurements. This segmentation allows each model to be calibrated independently with appropriate measurements, achieving complete convergence while maintaining process feasibility.
2Manufacturing precision
If separate calibration of optical and resist models is performed using aerial image measurements, then model accuracy and predictability improve, but measurement complexity and device requirements increase
Solution Approach 1:
The patent introduces an aerial image measurement system as an intermediary device that captures the optical model's output before resist processing. This intermediary measurement enables separate calibration of the optical model, improving overall accuracy while isolating the complexity of aerial image capture from the resist measurement process.
3Reliability
If separate calibration using aerial image measurements is implemented, then pattern transfer predictability improves, but the calibration process requires additional measurement steps and time
Solution Approach 1:
The patent performs aerial image measurements as a preliminary step before resist pattern measurements. By capturing and using aerial image data to calibrate the optical model first, the system establishes an accurate baseline that accelerates the subsequent resist model calibration and reduces the need for extensive iterative recalibration.
Solution Approach 2:
The patent implements a feedback mechanism where aerial image measurements are used to adjust and refine the optical model parameters, which then inform the resist model calibration. This feedback loop ensures accurate pattern transfer predictability while systematically reducing the number of recalibration iterations needed.
4Manufacturing precision
If extensive recalibration is performed with process changes, then model accuracy is maintained, but productivity and manufacturing efficiency decrease
Solution Approach 1:
By segmenting the calibration into separate optical and resist model calibrations with distinct measurement requirements, the patent enables selective recalibration. When process parameters change, only the affected model component needs recalibration rather than the entire combined model, significantly improving manufacturing efficiency while maintaining accuracy.
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 results in more accurate verification of circuit patterns and process control, enabling better prediction of pattern transfer from mask to wafer and reducing the need for extensive recalibration with process changes.
Implementation Method 1
measuring an aerial image using an image sensor array to produce a measured sensor image
Data Source
AI summary
A method for separately calibrating an optical model and a resist model of lithography process using information derived from in-situ aerial image measurements to improve the calibration of both the optical model and the resist model components of the lithography simulation model. Aerial images produced by an exposure tool are measured using an image sensor array loaded into the exposure tool. Multiple embodiments of measuring aerial image information and using the measured aerial image information to calibrate the optical model and the resist model are disclosed. The method of the invention creates more accurate and separable optical and resist models, leading to better predictability of the pattern transfer process from mask to wafer, more accurate verification of circuit patterns and how they will actually print in production, and more accurate model-based process control in the wafer fabrication facility.