Optical Proximity Correction Using Iterative Lithography Simulation
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Solution Overview
Problem
Current optical proximity correction (OPC) methods in semiconductor integrated circuit manufacturing are not entirely satisfactory in producing smaller, sharper, and more uniform features due to issues like corner rounding and edge placement errors as device size shrinks, necessitating advances in OPC to improve IC density, performance, and yield.
Innovation Solution
A method involving sub-resolution assist features (SRAFs) and optical proximity correction processes, using both model-based and rule-based processes to modify mask features, add or remove SRAFs, and perform iterative simulations and evaluations to optimize feature formation on the substrate, ensuring accurate and precise pattern transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If device size is shrunk to increase IC density, then production efficiency and cost are improved, but optical interference effects (diffraction, fringing, interference) cause pattern variations (corner rounding, edge placement errors) that worsen manufacturing precision
Solution Approach 1:
The patent applies preliminary action by performing optical proximity correction (OPC) modifications to the mask design before actual photolithography manufacturing. The system predicts optical interference effects and pre-adjusts mask features (adding assist features, modifying shapes) so that the final printed pattern achieves the desired geometry despite diffraction and interference during exposure
Solution Approach 2:
The patent uses computational modeling and simulation to create a virtual copy of the photolithography process. By simulating how light interacts with the mask pattern and predicting the resulting substrate pattern, the system can evaluate and optimize mask designs before physical manufacturing, allowing precise control of pattern formation at scaled dimensions
2Manufacturing precision
If current OPC methods are used to correct pattern variations, then some precision is improved, but the methods are not entirely satisfactory in producing smaller, sharper, and more uniform features
Solution Approach 1:
The patent implements feedback by using lithography simulation and evaluation to assess the effectiveness of OPC modifications, then using this information to iteratively improve the mask design. The system evaluates whether corrections achieve the desired feature sharpness and uniformity, and adjusts the OPC strategy accordingly to meet design criteria
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 method enhances the formation of smaller, sharper, and more uniform features by correcting optical proximity effects, improving edge placement accuracy, and increasing the yield of semiconductor manufacturing processes.
Implementation Method 1
ICs are typically assembled by layering features on a semiconductor substrate using a set of photolithographic masks. During a photolithographic exposure, radiation such as ultraviolet light passes through or reflects off the mask before striking a photoresist coating on the substrate.
Implementation Method 2
behaviors of light such as diffraction, fringing, and interference become more pronounced as device size shrinks
Implementation Method 3
behaviors of light such as diffraction, fringing, and interference become more pronounced as device size shrinks
Data Source
AI summary
A method for performing OPC and evaluating OPC solutions is disclosed. An exemplary method includes receiving a design database corresponding to an IC circuit mask. A first lithography simulation and evaluation is performed on the design database utilizing a first set of performance indexes. A modification is made to the design database based on a result of performing the first lithography simulation and evaluation. A second lithography simulation and evaluation is performed on the design database utilizing a second set of performance indexes to verify the modification. If necessary, the design database is modified again based on a result of the second lithography simulation and evaluation. The modified design database is provided to a mask manufacturer for manufacturing the mask corresponding to the modified design database.