Dynamic Lithographic Exposure for Photoresist Depth of Focus
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Solution Overview
Problem
As the resolution of photolithography tools improves, the depth of focus of electromagnetic radiation decreases, leading to a shrinking process window, which can result in inadequate exposure of the photoresist layer and potential integrated chip failure due to sections not being properly printed.
Innovation Solution
A dynamic lithographic exposure method that changes the focus of electromagnetic radiation during exposure, allowing it to have a plurality of different depths of focus spanning various regions of the photosensitive material, thereby increasing the cumulative depth of focus and expanding the process window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the resolution of photolithography tools is improved, then the manufacturing precision is improved, but the depth of focus decreases leading to a shrinking process window
Solution Approach 1:
The patent applies dynamics by making the focus position variable rather than fixed. The system dynamically adjusts the focus position during the exposure process, allowing the depth of focus to be optimized for different regions of the photoresist layer. This dynamic focus adjustment resolves the contradiction by enabling high resolution while maintaining an adequate process window through real-time adaptation.
Solution Approach 2:
The patent introduces a temporal dimension to the focus parameter by varying it over time during exposure. Instead of a single static focus position, the system employs multiple focus positions at different time points, effectively adding a time dimension to the focus control. This allows the system to achieve both high resolution and sufficient process window by exposing different regions of the photoresist at different focus positions.
2Manufacturing precision
If the resolution of photolithography tools is improved, then the manufacturing precision is improved, but sections of the photoresist layer may not be properly exposed leading to chip failure
Solution Approach 1:
The patent applies segmentation by dividing the exposure process into multiple stages, each targeting different regions of the photoresist layer with appropriately optimized focus positions. Instead of attempting to expose the entire layer at a single focus position, the system segments the exposure task and executes it across multiple focus settings, ensuring all sections receive adequate exposure while maintaining high resolution.
3Device complexity
If a fixed focus position is used during exposure, then the device complexity is reduced, but the process window shrinks and exposure quality deteriorates
Solution Approach 1:
The patent applies parameter changes by varying the focus position parameter during the exposure process. Instead of maintaining a constant focus position, the system changes the focus parameter to match the depth variations in the photoresist layer. This parameter variation resolves the contradiction by expanding the effective process window without requiring complex additional hardware, as it leverages existing focus adjustment capabilities.
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 exposure of the photosensitive material by increasing the process window by over 30% and prolongs the lifetime of photolithography tools by compensating for optical element decay, ensuring proper feature printing and reducing yield loss.
Implementation Method 1
exposing the photosensitive material to electromagnetic radiation modifies a solubility of an exposed region within the photosensitive material
Data Source
AI summary
The present disclosure, in some embodiments, relates to a method of developing a photosensitive material. The method includes forming a photosensitive material over a substrate. The photosensitive material is exposed to electromagnetic radiation focused at a plurality of different heights over the substrate. The plurality of different heights are vertically separated from one another and are disposed within the photosensitive material along a vertical path that extends in a direction perpendicular to an upper surface of the photosensitive material. The photosensitive material is developed to remove a soluble region.