Sacrificial Bracing for High Aspect Ratio Structure Drying
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Solution Overview
Problem
High aspect ratio structures in semiconductor substrates face challenges during drying due to capillary forces, leading to collapse and stiction issues, which existing methods such as using low surface tension rinsing fluids, supercritical fluids, mechanical bracing, and surface modification do not fully address, especially for higher aspect ratio structures.
Innovation Solution
A method involving the deposition of a solution containing a polymer component, a nanoparticle component, and a solvent between high aspect ratio structures, where the solvent evaporates to precipitate a sacrificial bracing material that fills the structures, followed by plasma removal to counter capillary forces without damaging the structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If deionized water or low surface tension rinsing fluids are used, then the rinsing process can be performed, but capillary forces during drying cause HAR structures to collapse and stiction occurs
Solution Approach 1:
A sacrificial bracing material is deposited into the HAR structures before the drying step. This preliminary action provides mechanical support during the critical drying phase when capillary forces would otherwise cause collapse. The bracing material is removed after drying is complete, having served its protective function.
Solution Approach 2:
The sacrificial bracing material acts as an intermediary element between the HAR structures and the drying process. It temporarily fills the spaces between structures to prevent them from collapsing under capillary forces, then is removed via plasma treatment after it has fulfilled its protective role.
2Reliability
If supercritical fluids are used to dissolve and flush rinsing fluid, then drying can be achieved without capillary forces, but equipment costs and process complexity increase significantly
Solution Approach 1:
Instead of using expensive and complex supercritical fluid equipment, the patent employs a disposable sacrificial bracing material that is deposited, used temporarily to prevent collapse, and then removed via plasma treatment. This approach achieves the same protective function at lower cost and with simpler equipment.
Solution Approach 2:
The patent replaces the mechanical/physical system of supercritical fluid processing with a chemical deposition and plasma removal system. The sacrificial bracing material provides mechanical support during drying, and plasma treatment removes the material, substituting the complex supercritical fluid mechanism with simpler, more cost-effective processes.
3Reliability
If permanent mechanical bracing structures are added, then HAR structures are supported during processing, but cost and process complexity increase, impacting throughput and yield
Solution Approach 1:
The sacrificial bracing material is designed to be temporary and disposable. It is deposited to provide support during critical processing steps, then removed via plasma treatment. This discarding approach eliminates the need for permanent bracing structures that would complicate subsequent processing and reduce throughput.
Solution Approach 2:
The support function is extracted as a separate, temporary component (sacrificial bracing material) rather than being integrated into the permanent structure. This allows the support to be added only when needed and removed afterward, avoiding the continuous presence of bracing structures that would impact productivity.
4Reliability
If freeze drying is used to eliminate collapse by sublimating frozen solvent, then HAR structures are protected, but cost increases and throughput decreases
Solution Approach 1:
Instead of changing the phase of the solvent through freezing and sublimation (freeze drying), the patent uses parameter changes in the sacrificial bracing material deposition and plasma treatment processes. The bracing material is deposited in solution, dries to form a solid support structure, and is then removed by plasma treatment, avoiding the lengthy freeze drying process.
5Reliability
If surface modification is performed to alter contact angle and minimize Laplace pressure, then collapse performance improves, but new tailored molecules are required and structures may still deform during drying
Solution Approach 1:
The sacrificial bracing material is deposited as a preliminary action before drying occurs. This provides immediate mechanical support during the critical drying phase, eliminating the need for surface modification to alter contact angles. The bracing material physically prevents collapse regardless of surface properties.
Solution Approach 2:
The sacrificial bracing material serves as an intermediary mechanical support system that decouples the drying process from the HAR structure. Instead of modifying the HAR structure surface to manage capillary forces, the bracing material provides a physical barrier that prevents collapse independent of surface properties.
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 by increasing the glass transition temperature of the sacrificial bracing material, allowing for faster plasma removal, higher throughput, and reduced surface tension, while maintaining structural integrity.
Implementation Method 1
As the solvent evaporates, a sacrificial bracing material precipitates out of solution and at least partially fills the plurality of HAR structures
Implementation Method 2
exposing the substrate to plasma generated using a plasma gas chemistry to volatilize the sacrificial bracing material
Data Source
AI summary
A method for drying a substrate including a plurality of high aspect ratio (HAR) structures includes, after at least one of (i) wet etching, and (ii) wet cleaning, and (iii) wet rinsing the substrate using at least one of (a) wet etching solution, and (b) wet cleaning solution, and (c) wet rinsing solution, respectively, and without drying the substrate: depositing, between the plurality of HAR structures, a solution that includes a polymer component, a nanoparticle component, and a solvent; wherein as the solvent evaporates, a sacrificial bracing material precipitates out of solution and at least partially fills the plurality of HAR structures, the sacrificial bracing material including (i) polymer material from the polymer component of the solution and (ii) nanoparticle material from the nanoparticle component of the solution; and exposing the substrate to plasma generated using a plasma gas chemistry to volatilize the sacrificial bracing material.