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, with existing solutions like low-surface-tension rinsing fluids, supercritical fluids, mechanical bracing, and surface modification either being ineffective or costly and complex.
Innovation Solution
A method using a polymer-based sacrificial bracing material that displaces fluid between high aspect ratio structures, precipitates, and is removed through non-plasma based stimuli such as UV light, heat, or chemicals, forming a mechanical brace to counter capillary forces without surface modification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If deionized water or low-surface-tension rinsing fluids are used for drying HAR structures, then the drying process is simple and low-cost, but capillary forces cause structure collapse and stiction
Solution Approach 1:
A sacrificial bracing material is introduced as an intermediary substance that temporarily supports HAR structures during drying. The material is deposited into structures, dried to form mechanical braces, and then removed after drying is complete, mediating between the conflicting requirements of simple drying and structure stability
Solution Approach 2:
The sacrificial bracing material is deposited and dried in advance before the final drying of HAR structures. This preliminary action creates mechanical support braces that prevent collapse during the subsequent drying process, addressing the stability issue before it occurs
2Reliability
If supercritical fluids are used for drying HAR structures, then collapse and stiction are prevented, but equipment cost and process complexity increase significantly
Solution Approach 1:
The sacrificial bracing material is a temporary, low-cost, disposable structure that provides mechanical support only during the critical drying phase. It is intentionally designed to be removed after serving its brief protective function, replacing expensive supercritical fluid equipment with inexpensive temporary braces
Solution Approach 2:
The complex supercritical fluid drying system is replaced with a simple mechanical bracing approach. Instead of using sophisticated fluid dynamics and phase transition control, the solution uses straightforward mechanical support structures that are easier to implement and remove
3Reliability
If permanent mechanical bracing structures are added to support HAR structures, then structure collapse is prevented, but cost and process complexity increase and throughput decreases
Solution Approach 1:
The mechanical bracing structures are designed as temporary sacrificial elements that are discarded after serving their protective function. The bracing material is removed after drying completes, allowing the process to proceed to next steps without permanent additions that would reduce throughput
Solution Approach 2:
The bracing material properties are specifically designed to change during the process - it transitions from a deposited state that provides mechanical support to a removed state after drying. This parameter change allows the same material to serve both protective and disposable functions, maintaining productivity
4Reliability
If surface modification is performed on HAR structure sidewalls, then collapse resistance is improved, but additional process steps are required and structures still deform during drying
Solution Approach 1:
Instead of modifying the HAR structure sidewalls directly, the invention introduces an external sacrificial bracing material as a mediator that provides support from the outside. This avoids the complexity of surface modification chemistry while still preventing collapse during drying
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
Effectively prevents collapse of high aspect ratio structures during drying by completely removing the sacrificial bracing material without damaging the structures, improving yield and reducing costs compared to existing methods.
Implementation Method 1
After the solvent evaporates, the bracing material precipitates out of solution and at least partially fills the plurality of HAR structures
Implementation Method 2
The plurality of HAR structures are exposed to non-plasma based stimuli to remove the bracing material
Implementation Method 3
The plurality of HAR structures are exposed to non-plasma based stimuli 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 is performed after at least one of wet etching and/or wet cleaning the substrate using at least one of wet etching fluid and/or wet cleaning fluid, 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 plurality of HAR structures are exposed to non-plasma based stimuli to remove the bracing material.