Sacrificial Bracing for High Aspect Ratio Structure Drying
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Solution Overview
Problem
High aspect ratio structures in semiconductor substrates face collapse and stiction issues during drying due to capillary forces, which existing methods such as using low surface tension rinsing fluids, supercritical fluids, permanent mechanical bracing, and surface modification fail to fully address, especially for structures with high aspect ratios.
Innovation Solution
A method involving the use of a solvent with a bracing material that precipitates out of solution to fill the structures, followed by exposure to hydrogen-rich plasma chemistry to dry the substrate without damaging the structures, using a system with a processing chamber, substrate support, and gas delivery system to manage plasma generation and fluid displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If deionized water or low surface tension rinsing fluids are used for drying HAR structures, then the drying process can be performed, but capillary forces cause structure collapse and stiction
Solution Approach 1:
A sacrificial bracing material is deposited into the HAR structures before the drying process occurs. This bracing material provides mechanical support during drying to prevent collapse, and is subsequently removed after drying completes successfully.
Solution Approach 2:
The sacrificial bracing material acts as an intermediary element between the HAR structures and the drying environment. It temporarily supports the structures during the harmful drying phase, then is removed to leave the structures intact.
2Strength
If supercritical fluids are used for drying HAR structures, then capillary forces are eliminated, but equipment cost and process complexity increase significantly
Solution Approach 1:
Instead of using expensive and complex supercritical fluid equipment, a simple sacrificial bracing material is used that can be easily deposited and removed with standard fabrication tools. The bracing material serves its purpose temporarily and is then discarded.
Solution Approach 2:
The invention changes the approach from modifying the drying fluid properties (as in supercritical drying) to modifying the mechanical support properties of the structures by adding temporary bracing material.
3Strength
If permanent mechanical bracing structures are added to support HAR structures, then collapse is prevented, but cost and process complexity increase and throughput decreases
Solution Approach 1:
The sacrificial bracing material is deposited to provide support during drying, then systematically removed after drying completes. This temporary bracing approach provides the necessary support without the permanent complexity of mechanical bracing structures.
Solution Approach 2:
The harmful element (need for permanent mechanical bracing) is replaced by a temporary element that is subsequently extracted (removed) after serving its purpose, simplifying the overall process.
4Strength
If surface modification is performed on sidewalls of HAR structures, then stiction is reduced, but drying forces are not fully eliminated and new materials are required
Solution Approach 1:
The sacrificial bracing material is deposited before drying to provide mechanical support, preventing collapse at the source rather than attempting to modify surface properties to reduce stiction after collapse occurs.
Solution Approach 2:
The invention replaces chemical surface modification approaches with a mechanical support approach using sacrificial bracing material, which directly addresses the collapse problem through mechanical means rather than surface property changes.
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 effectively prevents collapse and stiction of high aspect ratio structures by using hydrogen-rich plasma to remove the sacrificial bracing material, enabling the use of sacrificial bracing for a wider range of structures without surface modification and equipment limitations.
Implementation Method 1
wherein after the solvent evaporates, the bracing material precipitates out of solution
Implementation Method 2
the bracing material precipitates out of solution and at least partially fills the plurality of HAR structures
Implementation Method 3
exposing the substrate to plasma generated using a plasma gas chemistry that is hydrogen rich to remove the bracing material
Data Source
AI summary
Systems and methods for drying a substrate including a plurality of high aspect ratio (HAR) structures are performed after at least one of wet etching and/or wet cleaning the substrate using at least one of wet etching solution and/or wet cleaning solution, respectively, and without drying the substrate. Fluid between the plurality of HAR structures is displaced using a solvent including a bracing material. After the solvent evaporates, the bracing material precipitates out of solution and at least partially fills the plurality of HAR structures. The substrate is exposed to plasma generated using a plasma gas chemistry that is hydrogen rich to remove the bracing material thereby drying the substrate including the HAR structures without damaging the plurality of HAR structures.