OPC Model Refinement for Semiconductor Feature Fidelity
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Solution Overview
Problem
The increasing demand for smaller and more densely packed semiconductor components poses challenges for photolithography due to optical effects like diffraction and proximity effects, which existing optical proximity correction (OPC) techniques have not fully addressed, necessitating refinements in mask design and OPC enhancement.
Innovation Solution
A method for refining the OPC model by designing and measuring mask features, comparing them to actual structures on the wafer, and iteratively adjusting the OPC tool to improve fidelity, incorporating actual mask error and fitness values to optimize feature size and sub-resolution assist features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If photolithography is used to form smaller semiconductor features, then component density and integration are improved, but optical effects like diffraction and proximity effects cause deformation and reduce manufacturing precision
Solution Approach 1:
The patent applies preliminary action by pre-compensating for optical effects through OPC mask design. The mask patterns are intentionally modified before photolithography to counteract anticipated diffraction and proximity effects, ensuring that the final fabricated features match the desired layout despite optical distortions.
Solution Approach 2:
The patent employs parameter changes by adjusting mask pattern parameters (such as feature sizes, spacing, and shapes) to compensate for optical effects. The OPC process modifies these parameters iteratively based on fitness evaluations, transforming the mask design parameters to achieve better fidelity in the final fabricated features.
2Manufacturing precision
If existing OPC techniques are used for mask design, then some optical effects are compensated, but the techniques have not fully addressed diffraction and proximity effects, leaving room for further refinement
Solution Approach 1:
The patent implements feedback through an iterative OPC refinement process. Fitness values are calculated by comparing simulated wafer images with target layouts, and these feedback signals guide successive modifications to the OPC model and mask design, progressively improving compensation accuracy while managing complexity through systematic iteration.
Solution Approach 2:
The patent applies dynamics by making the OPC model adaptive and iterative rather than static. The OPC parameters and mask designs are dynamically adjusted through multiple refinement cycles, allowing the system to evolve from initial approximations to optimized solutions that better handle diffraction and proximity effects.
3Length of moving object
If mask features are made smaller to achieve higher density, then component size is reduced, but optical distortion increases due to diffraction and proximity effects
Solution Approach 1:
The patent applies local quality by applying different OPC compensation strategies to different regions and feature types within the mask design. Sub-resolution assist features (SRAFs) are selectively added in specific locations, and OPC parameters are locally adjusted based on the particular geometric and optical characteristics of each feature region, optimizing compensation for diffraction and proximity effects at local scales.
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 enhances the accuracy and efficiency of OPC, allowing for the formation of smaller, more precise semiconductor features by iteratively refining the OPC model based on actual mask and wafer measurements, thereby improving the mask design and reducing errors.
Implementation Method 1
measuring the at least one mask feature, measuring the at least one structure to determine its fidelity to the layout
Implementation Method 2
optical effects like diffraction and proximity effects
Implementation Method 3
optical effects like diffraction and proximity effects
Data Source
AI summary
A method for generating or refining an OPC model for use in wafer fabrication. A predetermined feature layout is used to prepare a mask for use in, for example, a photolithographic process. The mask is used to create structures corresponding to mask features on a semiconductor wafer using the mask. Measurements of the actual mask features and wafer features may then be assessed and correlated, and the results used to generate an OPC model or refine an existing one. In addition, the OPC may be used to simulate a fabrication operation by applying the OPC tool to a predetermined layout to produce a mask image and a wafer image, and then comparing the predetermined layout to the simulated wafer image to determine at least one fitness value.