Sub-Resolution Assist Features With Reusable TCC Kernels
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Solution Overview
Problem
Conventional SRAF placement techniques in semiconductor manufacturing suffer from unsatisfactory accuracy and long turn-around-times due to inadequate consideration of exposure tool conditions and mask three-dimensional effects, with rule-based methods being too fast but inaccurate, and inverse lithography technology being too slow.
Innovation Solution
A method that considers all orders of eigenvalues and eigenfunctions of the transmission cross coefficient to calculate a kernel, accounting for exposure tool conditions and mask 3D effects, allowing for accurate SRAF placement with reduced turn-around-time by reusing the kernel for different mask designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If rule-based SRAF placement techniques are used, then turn-around-time is reduced, but manufacturing precision deteriorates
Solution Approach 1:
The patent pre-calculates and stores a kernel based on exposure tool conditions and mask 3D effects before SRAF placement. This preliminary computation of the kernel (which encapsulates the optical system's response) allows subsequent SRAF placements to use this pre-computed data, avoiding repeated full calculations and reducing turn-around-time while maintaining accuracy through the stored kernel's consideration of all exposure parameters.
2Manufacturing precision
If inverse lithography technology is used, then manufacturing precision is improved, but productivity deteriorates
Solution Approach 1:
The patent performs preliminary computation of the kernel that incorporates all exposure tool conditions and mask 3D effects. This pre-computed kernel captures the complete optical system behavior, enabling accurate SRAF placement without requiring repeated full inverse lithography calculations, thus achieving high precision with improved productivity.
Solution Approach 2:
The patent transforms the complex inverse lithography problem into a kernel-based approach where the system's optical parameters (exposure conditions, mask 3D effects) are pre-processed into a reusable kernel. This parameter transformation allows accurate SRAF placement through simpler operations on the kernel, reducing computational time while maintaining the precision of full inverse lithography technology.
3Device complexity
If conventional SRAF placement techniques are used, then device complexity is reduced, but manufacturing precision deteriorates
Solution Approach 1:
The patent introduces a kernel as an intermediary that bridges the gap between simple rule-based methods and complex inverse lithography technology. The kernel pre-encapsulates the effects of exposure tool conditions and mask 3D effects, serving as a mediator that enables accurate SRAF placement without requiring the full complexity of repeated inverse lithography calculations, thus improving precision while managing device complexity.
Data Source
AI summary
Methods of semiconductor device fabrication are provided. In an embodiment, a method of semiconductor device fabrication includes receiving a first mask design comprising a first mask function, determining a transmission cross coefficient (TCC) of an exposure tool, decomposing the TCC into a plurality orders of eigenvalues and a plurality orders of eigenfunctions, calculating a kernel based on the plurality orders of eigenvalues and the plurality orders of eigenfunctions; and determining a first sub-resolution assist feature (SRAF) seed map by convoluting the first mask function and the kernel.