Photolithography Mask Analysis via Aerial Image Combination
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Solution Overview
Problem
Current photolithography methods for producing smaller semiconductor structures require precise alignment and manufacturing of multiple masks, leading to increased complexity and cost, with existing analysis tools unable to assess the interaction of multiple masks, resulting in overlay errors and inefficiencies in double- or multiple-exposure processes.
Innovation Solution
A method and apparatus for analyzing a group of photolithography masks by recording and combining aerial images of individual masks, simulating double- or multiple-exposure processes through pixel-based combination and photoresist simulation, allowing evaluation of mask interactions and overlay errors without the need for extensive test series.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple masks are used for double- or multiple-exposure processes to produce smaller semiconductor structures, then the manufacturing precision and resolution are improved, but the device complexity and alignment requirements increase
Solution Approach 1:
The patent combines multiple aerial images from different masks into a single simulated aerial image that represents the cumulative effect of all exposures. This merging approach allows evaluation of the complete multi-mask process through one unified analysis, reducing the complexity of assessing each mask separately while maintaining manufacturing precision.
Solution Approach 2:
The patent creates a simulated aerial image that copies and combines the optical effects of multiple actual mask exposures. This virtual copy allows comprehensive evaluation of mask interactions and overlay errors without requiring physical test wafers for each mask combination, thereby reducing device complexity while preserving resolution accuracy.
2Manufacturing precision
If multiple masks are used for double- or multiple-exposure processes, then the manufacturing precision is improved, but the time required for analysis and evaluation increases
Solution Approach 1:
The patent performs preliminary combination of aerial images from all masks before actual wafer fabrication. By simulating and evaluating the complete multi-mask exposure sequence in advance, potential alignment issues and overlay errors are identified and corrected before production, reducing the time required for iterative testing and adjustment during manufacturing.
Solution Approach 2:
The simulated aerial image serves as an intermediary representation that consolidates information from multiple individual mask aerial images. This intermediate model allows comprehensive alignment evaluation without requiring sequential analysis of each mask separately or physical test wafers, thereby reducing analysis time while maintaining alignment precision.
3Ease of manufacture
If individual mask aerial images are analyzed separately, then the analysis process is simple, but the interaction and overlay errors between masks cannot be detected
Solution Approach 1:
The patent merges individual mask aerial images into a single simulated aerial image that preserves and combines all optical and geometric information. This unified representation maintains the simplicity of individual image analysis while enabling detection of interactions and overlay errors that would be invisible in separate analyses, thereby improving reliability without sacrificing ease of analysis.
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
Enables accurate simulation and evaluation of mask interactions, reducing overlay errors and production costs by analyzing the alignment and behavior of multiple masks, thereby improving the precision and efficiency of semiconductor structure manufacturing.
Implementation Method 1
a first aerial image of a first one of the at least two masks is recorded, digitized and stored in a data structure
Data Source
AI summary
The invention relates to a method for analyzing a group of at least two masks for photolithography, wherein each of the masks comprises a substructure of a total structure, which is to be introduced in a layer of the wafer in the lithographic process, and the total structure is introduced in the layer of the wafer by introducing the substructures in sequence. In this method, a first aerial image of a first one of the at least two masks is recorded, digitized and stored in a data structure. Then, a second aerial image of a second one of the at least two masks is recorded, digitized and stored in a data structure. A combination image is generated from the data of the first and second aerial images, which combination image is represented and/or evaluated.