Collapse-Free Drying of High Aspect Ratio Structures
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Solution Overview
Problem
The challenge in semiconductor device fabrication is the collapse and stiction of high aspect ratio structures during drying due to capillary forces generated by traditional wet processing methods, which are not effectively addressed by existing solutions such as alternative rinsing liquids with lower surface tension or supercritical fluids, due to equipment costs, process complexity, and yield limitations.
Innovation Solution
A method involving a sacrificial bracing drying system that uses a drying solution with a solvent that forms a solid to fill high aspect ratio spaces, which is then removed using a downstream plasma, spinning, and controlled evaporation to counteract capillary forces, preventing feature collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional wet processing methods are used for drying, then the process is simple and cost-effective, but capillary forces cause high aspect ratio features to collapse and stiction occurs
Solution Approach 1:
The patent introduces an intermediary substance (drying solution with controlled surface tension and viscosity) that mediates between the liquid to be removed and the high aspect ratio features. This drying solution acts as a temporary support structure during the drying process, preventing capillary forces from directly acting on the features. The intermediary material provides mechanical bracing while allowing controlled removal of the original liquid.
Solution Approach 2:
The patent changes the physical parameters of the drying environment by controlling the surface tension and viscosity of the drying solution, and by regulating temperature and pressure conditions during drying. These parameter changes allow the drying process to proceed without generating excessive capillary forces that would cause feature collapse, while still achieving effective liquid removal.
2Manufacturing precision
If alternative rinsing liquids with lower surface tension are used, then feature collapse is reduced, but equipment costs and process complexity increase
Solution Approach 1:
The patent modifies the surface tension parameter of the drying solution to be lower than traditional rinsing liquids, which reduces capillary forces and prevents feature collapse. By carefully selecting and controlling the surface tension parameter, the patent achieves better protection for high aspect ratio features while maintaining process simplicity and avoiding the need for complex equipment modifications.
3Manufacturing precision
If supercritical fluids are used for drying, then capillary forces are eliminated, but equipment costs and process complexity significantly increase
Solution Approach 1:
The patent changes the physical parameters of the drying solution (surface tension, viscosity, temperature) to achieve a state where capillary forces are sufficiently reduced to prevent feature collapse, without requiring the extreme conditions of supercritical fluids. This parameter optimization allows effective drying with standard equipment, avoiding the high costs and complexity of supercritical fluid systems.
Solution Approach 2:
The patent uses a disposable or easily replaceable drying solution that can be applied and then removed without requiring expensive, complex equipment. This approach substitutes the need for costly supercritical fluid equipment with a simpler, consumable-based solution that achieves the same protective effect during drying.
4Reliability
If higher aspect ratio structures are fabricated to achieve desired device performance, then device performance is improved, but susceptibility to collapse and stiction during drying increases
Solution Approach 1:
The patent introduces a drying solution as an intermediary material that provides temporary mechanical support to high aspect ratio features during the vulnerable drying phase. This intermediary substance allows the fabrication of higher aspect ratio structures for improved device performance while protecting them from collapse during processing.
Solution Approach 2:
The patent applies the drying solution beforehand to provide cushioning and mechanical support to high aspect ratio features before the actual drying process begins. This prior cushioning prevents the features from being subjected to damaging capillary forces during liquid removal, enabling the safe fabrication of higher aspect ratio structures for improved device performance.
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 achieves 0% feature collapse in high aspect ratio structures, significantly improving yield and throughput by effectively eliminating capillary forces during the drying process.
Implementation Method 1
Some of the solvent is removed from the drying solution to form a solid from the solution
Implementation Method 2
The solid is removed using a downstream plasma
Implementation Method 3
An electrostatic chuck (ESC) for supporting and electrostatically clamping the wet substrate
Implementation Method 4
A vacuum pump is in fluid connection with the chamber
Data Source
AI summary
A method, for drying an etched layer with a plurality of structures with etched spaces between the plurality of structures is provided. A liquid is provided within the spaces on the etched layer. The liquid is displaced with a drying solution with a solvent. Some of the solvent is removed from the drying solution to form a solid from the solution, wherein the solid at least fill half the height of the etched high aspect ratio spaces. The solid is removed.