Photolithography Process Model for CAR/PEB Impact
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Solution Overview
Problem
Inaccuracies in photolithography process models, particularly due to ignored physical effects like Z-direction resist profile diffusion and CAR/PEB effects, negatively impact semiconductor manufacturing, especially at deep submicron scales, affecting optical proximity correction and etch processes.
Innovation Solution
A process model that accounts for the impact of CAR/PEB on the resist profile by modeling defocused aerial images and using Gaussian kernels to differentiate diffusion lengths between the Z and X/Y directions, enhancing accuracy without sacrificing computational performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If physical effects like Z-direction resist profile diffusion and CAR/PEB effects are included in the process model, then manufacturing precision improves, but device complexity increases
Solution Approach 1:
The patent segments the aerial image modeling into multiple discrete depth planes (e.g., first depth plane, second depth plane, third depth plane) along the Z-axis. Each plane is modeled independently with its own aerial image and diffusion parameters, allowing the complex 3D diffusion process to be broken down into manageable 2D calculations that can be performed sequentially, thus improving accuracy without prohibitively increasing computational complexity
Solution Approach 2:
The patent transitions from conventional 2D aerial image modeling (X/Y directions only) to 3D modeling by incorporating the Z-depth dimension. This is achieved by calculating aerial images at multiple depth planes and applying depth-dependent diffusion, thereby capturing the third dimension of acid diffusion while maintaining computational efficiency through systematic approximation methods
2Manufacturing precision
If multiple depth planes are modeled to account for Z-direction diffusion, then manufacturing precision improves, but computation time increases
Solution Approach 1:
The patent applies partial action by selecting a representative subset of depth planes (e.g., first, second, and third depth planes) rather than modeling every possible depth increment. This provides sufficient accuracy for capturing Z-direction diffusion effects while avoiding the computational burden of excessive discretization, achieving an optimal balance between precision and simulation speed
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 improves the accuracy of photolithography process models, reducing errors associated with CAR/PEB effects and enhancing the robustness of subsequent processes like etch, while maintaining fast simulation times.
Implementation Method 1
diffuses the aerial image using a Gaussian kernel to account for the diffusion length difference between the Z direction and the X/Y directions
Data Source
AI summary
An embodiment provides systems and techniques for determining a process model. During operation, the system may receive a first optical model which models a first optical system of a photolithography process. Next, the system may use the first optical model to determine a second optical model that models a second latent image that is formed by the first optical system at a second distance. The system may also use the first optical model to determine a third optical model that models a third latent image that is formed by the first optical system at a third distance. Next, the system may receive process data which is obtained by subjecting a test layout to the photolithography process. The system may then determine a process model using the first optical model, the second optical model, the third optical model, the test layout, and the process data.