Depth-Dependent Etch Bias Modeling for Multi-Level Profiles
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Solution Overview
Problem
Current lithographic processes face challenges in accurately predicting and controlling the etch profiles of features at varying depths, leading to deviations from target dimensions due to etch bias, which complicates the manufacturing of complex three-dimensional structures like NAND memory.
Innovation Solution
A method involving an etch bias model that correlates etch bias with etch depth, utilizing a convolution of a mask and a filter, and potentially a machine learning model, to predict after-etch profiles, allowing for precise control of feature dimensions throughout the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used without depth-dependent bias correction, then the manufacturing process is simpler and faster, but the manufacturing precision of multi-level structures deteriorates due to dimensional deviations at varying etch depths
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing etch bias values in lookup tables during process development. During actual manufacturing, these pre-computed bias values are simply retrieved and applied to correct dimensional measurements at different etch depths, eliminating the need for complex real-time calculations while achieving high precision.
Solution Approach 2:
The patent introduces an intermediary approach by using lookup tables as intermediaries between the complex etch physics and the manufacturing process. These tables store pre-computed bias correction values that mediate between theoretical etch profiles and actual measured dimensions, allowing accurate prediction without solving complex equations in real-time.
2Manufacturing precision
If etch bias correction models are applied to achieve accurate feature dimensions, then manufacturing precision improves, but computational resources and processing time increase
Solution Approach 1:
The patent performs computationally intensive modeling and lookup table generation during the development phase rather than during production. This preliminary action shifts the computational burden from real-time manufacturing to offline process characterization, enabling fast lookup during actual etching without compromising precision.
Solution Approach 2:
The patent uses simplified lookup table structures that replace complex real-time computational models. These tables provide accurate bias correction with minimal computational overhead, effectively replacing expensive continuous calculations with inexpensive discrete lookups during manufacturing.
3Adaptability or versatility
If multi-level etch processes are used to manufacture complex three-dimensional structures, then product functionality improves, but process control difficulty increases due to depth-dependent etch biases
Solution Approach 1:
The patent segments the etch bias correction into separate depth-dependent components by using multiple lookup tables, each corresponding to a specific etch depth level. This segmentation allows independent correction of bias at each level, making the overall process control manageable despite the complexity of multi-level structures.
Solution Approach 2:
The patent changes the control parameter from continuous real-time calculations to discrete lookup table queries based on etch depth. By transforming the control approach into parameter-based lookup rather than computational modeling, the system can handle complex multi-level structures with manageable process control.
Data Source
AI summary
Methods, systems, and computer software for predicting after-etch profiles of features at varying depths. A method can include accessing after-development resist profiles of features. The method can also include applying an etch bias model on the after-development resist profiles to obtain the after-etch profiles, where the etch bias model correlates an etch bias with an etch depth.