Hybrid Focus-Exposure Matrix for Semiconductor Lithography
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Solution Overview
Problem
In semiconductor fabrication, controlling critical dimensions of structures on a substrate is challenging due to drifts in focus and exposure settings of photolithography tools over time, which affect the characteristics of structures formed, necessitating effective methods to model and monitor these relationships for precise adjustments.
Innovation Solution
A hybrid focus-exposure matrix model is created using data from both optical measurement tools and scanning electron microscopes to form a comprehensive model that allows for accurate determination of optimal focus and exposure settings, enabling adjustments to maintain desired structure characteristics across semiconductor substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single measurement tool (either optical or electron microscope) is used to model focus-exposure relationships, then the modeling process is simpler, but the accuracy and reliability of the model is insufficient
Solution Approach 1:
The patent combines measurements from two different measurement tools (optical scatterometer and electron microscope) into a single hybrid focus-exposure matrix model. This merging of data sources improves model accuracy and reliability by capturing different aspects of structure characteristics that each tool measures effectively, resolving the contradiction between model accuracy and system complexity.
2Manufacturing precision
If focus and exposure settings are not monitored and adjusted, then the fabrication process is simpler and faster, but the critical dimension control deteriorates due to drift over time
Solution Approach 1:
The patent creates a hybrid focus-exposure matrix model in advance that captures the relationship between focus-exposure settings and structure characteristics. This preliminary modeling enables quick determination of optimal settings during production without requiring time-consuming iterative adjustments, thus maintaining critical dimension control while preserving fabrication efficiency.
Solution Approach 2:
The patent implements a feedback mechanism where actual structure measurements are compared against the hybrid focus-exposure matrix model to determine drift in focus and exposure settings. This feedback enables real-time identification and correction of setting drifts, maintaining manufacturing precision without continuously interrupting the fabrication process for manual adjustments.
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 hybrid model provides a more accurate method for controlling semiconductor fabrication by combining data from scatterometers and CD-SEM measurements, allowing for precise adjustments to focus and exposure settings, thereby ensuring consistent and optimal structure formation.
Implementation Method 1
Scatterometry refers to the process of measuring light spectra to determine the size of periodic structures
Implementation Method 2
Another tool that can be used to measure characteristics of structures formed into semiconductor substrates is a scanning electron microscope
Data Source
AI summary
A method for controlling semiconductor production through use of a hybrid Focus Exposure Matrix (FEM) model includes taking measurements of a set of structures formed onto a substrate. The method further includes using a FEM model to determine focus and exposure conditions used to form the structure The model was created through use of measurements of structures formed on a substrate under varying focus and exposure conditions, the measurements being taken using both an optical measurement tool and a scanning electron microscope.