Inverse Lithography SRAF Insertion for Mask Fidelity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional photolithographic processing techniques face challenges in accurately matching the pattern of features on a semiconductor wafer with the intended mask pattern due to optical distortions, which existing resolution enhancement techniques only partially address.
Innovation Solution
A system generates optimized mask layout data by calculating an inverse image of the target pattern using Fourier transforms and numerical de-convolution, incorporating sub-resolution assist features (SRAFs) to approximate non-printing features, constrained by manufacturability parameters, to improve printing fidelity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional resolution enhancement techniques are used to compensate for optical distortions, then printing fidelity is improved, but manufacturing precision is insufficient due to inability to fully match desired layout pattern
Solution Approach 1:
The patent applies inverse lithography by calculating the inverse image of the desired pattern through Fourier transforms and numerical de-convolution. Instead of forward-simulating how mask patterns print on wafers, the system inverts the process to directly compute the optimized mask layout that will produce the target pattern, fundamentally reversing the conventional approach to achieve superior pattern fidelity
Solution Approach 2:
The patent transforms the mask layout optimization problem by changing from direct geometric manipulation to frequency domain operations using Fourier transforms. This parameter transformation enables efficient calculation of the inverse image and allows the system to optimize multiple parameters simultaneously to achieve the desired printing fidelity
2Reliability
If subresolution assist features are added to improve printing fidelity, then image quality is enhanced, but device complexity increases
Solution Approach 1:
The patent extracts and separates subresolution assist features from the main printing features in the optimized mask layout. By identifying and isolating non-printing features through the inverse lithography calculation, the system can selectively add only the necessary SRAFs to improve image quality without unnecessarily complicating the overall layout data structure
Solution Approach 2:
The patent uses Fourier transforms and numerical de-convolution as mathematical intermediaries to bridge between the desired target pattern and the actual mask layout. These computational tools enable the system to calculate the optimal intermediate representation that includes SRAFs, mediating between the simple target pattern specification and the complex optimized mask layout
3Ease of manufacture
If conventional geometric rules are used for SRAF placement, then ease of manufacture is improved, but printing fidelity is insufficient
Solution Approach 1:
The patent fundamentally changes the approach to SRAF placement by transitioning from geometric rule-based methods to physics-based optical calculations. By using Fourier transforms and numerical de-convolution to determine SRAF positions and dimensions, the system achieves superior printing fidelity while still maintaining manufacturability through automated calculation
4Reliability
If extensive changes are made to mask features to compensate for distortions, then printing fidelity is improved, but device complexity increases
Solution Approach 1:
The patent applies inverse lithography by calculating the inverse image of the desired pattern through Fourier transforms and numerical de-convolution. Instead of forward-simulating how mask patterns print on wafers, the system inverts the process to directly compute the optimized mask layout that will produce the target pattern, fundamentally reversing the conventional approach to achieve superior pattern fidelity
Solution Approach 2:
The patent creates a universal optimization framework that simultaneously handles multiple distortion compensation tasks through the inverse lithography calculation. The Fourier transform-based approach universally applies to various pattern types and distortion scenarios, consolidating multiple correction functions into a single comprehensive calculation process
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 system significantly enhances the fidelity of the lithographic image to the desired layout pattern by accurately representing the target features on the semiconductor wafer, overcoming limitations of conventional techniques in handling optical distortions and improving manufacturability.
Implementation Method 1
A system generates optimized mask layout data by calculating an inverse image of the target pattern using Fourier transforms and numerical de-convolution
Implementation Method 2
A system generates optimized mask layout data by calculating an inverse image of the target pattern using Fourier transforms and numerical de-convolution
Data Source
AI summary
A system for producing mask layout data retrieves target layout data defining a pattern of features, or portion thereof and an optimized mask layout pattern that includes a number of printing and non-printing features. Mask layout data for one or more subresolution assist features (SRAFs) is then defined to approximate one or more non-printing features of the optimized mask layout pattern.