3D Lithography Resist Simulation via Radiation Interference
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Solution Overview
Problem
Current lithographic processes face challenges in accurately reproducing small feature sizes and high feature densities due to optical proximity effects, which are difficult to predict and correct, especially when features are smaller than the wavelength of light used, leading to non-linear pattern transfer and potential manufacturing defects.
Innovation Solution
A method is developed to simulate the three-dimensional spatial intensity distribution of radiation in the resist layer by calculating the incoherent sum and interference of forward and backward propagating radiation, allowing for a more accurate prediction of resist images and compensation for scattering effects, which are critical for improving image fidelity and pattern transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional two-dimensional resist models are used, then computational simplicity is maintained, but manufacturing precision deteriorates due to inability to account for three-dimensional standing wave effects and scattering
Solution Approach 1:
The patent transitions from conventional two-dimensional resist models to a three-dimensional simulation model that accounts for standing wave effects and scattering in the vertical dimension. This dimensional expansion enables accurate prediction of resist profile morphology by considering radiation intensity distribution throughout the depth of the resist layer, not just at the surface.
Solution Approach 2:
The patent introduces an interference factor as an intermediary parameter that quantifies the combined effect of forward and backward propagating radiation. This factor serves as a mediator between the complex electromagnetic interactions and the resist exposure model, enabling practical computation while capturing three-dimensional effects.
2Productivity
If features are made smaller than the wavelength of light, then feature density increases, but optical proximity effects become non-linear and difficult to predict
Solution Approach 1:
The patent incorporates scattering effects and standing wave formation as feedback mechanisms that continuously influence the radiation intensity distribution within the resist layer. By accounting for backward-propagating radiation that reflects off the substrate and interferes with forward-propagating radiation, the model captures the non-linear optical proximity effects that occur at high feature densities.
3Measurement precision
If three-dimensional radiation distribution is calculated including interference, then image fidelity improves, but computational requirements increase
Solution Approach 1:
The patent transforms the complex three-dimensional electromagnetic problem into a more computationally tractable form by changing parameters: it uses an interference factor that depends on depth into the resist layer, and calculates an incoherent sum of forward and backward propagating radiation. These parameter transformations maintain accuracy while reducing computational burden compared to full-wave electromagnetic simulations.
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 enables more precise control over the lithographic process, enhancing the reproduction of small features and reducing manufacturing defects by accounting for three-dimensional effects within the resist layer, thus improving the overall fidelity and accuracy of pattern transfer.
Implementation Method 1
calculating an interference of the forward propagating radiation in the resist layer and the backward propagating radiation in the resist layer
Implementation Method 2
compensation for scattering effects, which are critical for improving image fidelity and pattern transfer
Data Source
AI summary
Described herein is a method for simulating a three-dimensional spatial intensity distribution of radiation formed within a resist layer on a substrate resulting from an incident radiation, the method comprising: calculating an incoherent sum of forward propagating radiation in the resist layer and backward propagating radiation in the resist layer; calculating an interference of the forward propagating radiation in the resist layer and the backward propagating radiation in the resist layer; and calculating the three-dimensional spatial intensity distribution of radiation from the incoherent sum and the interference.