Sacrificial Solid Sealing for High-Aspect-Ratio Feature Protection
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Solution Overview
Problem
During semiconductor processing, high-aspect-ratio features are prone to collapse (toppling) when exposed to moisture-containing air as they are moved between processing tools, leading to defects and inoperability due to liquid condensate formation in openings between features.
Innovation Solution
The use of sacrificial materials to close openings between features, preventing condensate formation and oxidation, by forming and removing these materials at specific processing tools to protect the features during transfer through moist atmospheres.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-aspect-ratio features are exposed to moisture-containing air during transfer between processing tools, then the features can be moved to subsequent processing steps, but liquid condensate forms in openings between features causing feature collapse and device inoperability
Solution Approach 1:
A sacrificial material is introduced as an intermediary substance that fills openings between high-aspect-ratio features during transfer between processing tools. This sacrificial material prevents moisture-containing air from contacting the features and forming liquid condensate that would cause collapse. The sacrificial material is temporarily present during the critical transfer phase and is subsequently removed, allowing features to be exposed only when structurally stable.
2Reliability
If sacrificial materials are used to close openings between features, then feature collapse and oxidation are prevented during transfer, but additional processing steps are required to form and remove the sacrificial materials
Solution Approach 1:
The sacrificial material is applied in advance, before the features are transferred between processing tools, to preemptively close openings and prevent condensate formation. This preliminary action ensures features are protected from the outset during the vulnerable transfer phase, rather than requiring corrective actions after damage occurs.
Solution Approach 2:
The sacrificial material serves as a temporary, disposable element that is intentionally added to protect features during transfer, then completely removed in a subsequent processing step. The sacrificial material is discarded after fulfilling its protective function, with no need for recovery or reuse, simplifying the overall process despite the additional steps.
3Reliability
If features are protected from moisture during transfer, then oxidation is prevented, but the features must be exposed to moisture-containing air at some point for processing
Solution Approach 1:
The harmful element (moisture-containing air) is extracted or excluded from the environment surrounding the features during the critical transfer phase. By removing the harmful atmospheric condition rather than trying to protect the features directly, the sacrificial material creates a protected microenvironment that prevents both condensate formation and oxidation while allowing features to remain in their original state.
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 significantly reduces the likelihood of feature collapse and oxidation, ensuring the integrity of semiconductor devices by maintaining feature structure and preventing defects during processing.
Implementation Method 1
the liquid may create high surface tension forces that may cause the features to topple (e.g., collapse) toward each other
Implementation Method 2
portions of the one or more materials, and in some instances, portions of the semiconductor, may be removed, such as by wet and/or dry etching
Data Source
AI summary
In an example, a method may include closing an opening in a structure with a sacrificial material at a first processing tool, moving the structure from the first processing tool to a second processing tool while the opening is closed, and removing the sacrificial material at the second processing tool. The structure may be used in semiconductor devices, such as memory devices.