High Aspect Ratio Feature Collapse Repair via Plasma Etching
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Solution Overview
Problem
High aspect ratio nanostructures on semiconductor wafers often experience feature collapse during wet chemical treatment and drying processes due to capillary forces, leading to defects in semiconductor devices, with existing methods like supercritical carbon dioxide drying being costly and inefficient.
Innovation Solution
A method involving forming high aspect ratio features on silicon wafers, followed by wet processing and controlled drying, with a repair step using dry or wet etching to break bonds between adjacent features, specifically employing plasma etching and HF etching to reverse pattern collapse, and incorporating queue time control to ensure timely repair.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet chemical treatment and drying processes are used on high aspect ratio nanostructures, then cleaning effectiveness is improved, but pattern collapse occurs due to capillary forces
Solution Approach 1:
The patent applies a preliminary protective coating to the high aspect ratio nanostructures before wet processing. This coating prevents capillary forces during drying from causing pattern collapse, while allowing the wet cleaning process to effectively remove contaminants. The protective coating is subsequently removed after cleaning, leaving the cleaned structures intact without collapse.
Solution Approach 2:
The patent introduces an intermediary substance (protective coating) that mediates between the wet chemical treatment and the nanostructures. This intermediary allows the cleaning chemistry to access and clean the structures while preventing the harmful capillary forces from directly acting on the nanostructures during the drying phase.
2Ease of operation
If conventional drying methods are used after wet processing, then processing simplicity is maintained, but pattern collapse occurs
Solution Approach 1:
The protective coating is applied in advance before the drying step, preparing the structures to withstand the drying process without requiring complex modified drying procedures. This maintains processing simplicity while preventing pattern collapse through the preliminary protective measure.
3Quantity of substance
If high aspect ratio features with characteristic dimension less than 40 nm are formed, then device density is improved, but susceptibility to pattern collapse increases
Solution Approach 1:
The protective coating is applied beforehand to the high aspect ratio features, providing immediate protection against pattern collapse. This allows the fabrication process to successfully create high density structures with characteristic dimensions less than 40 nm without sacrificing their stability during subsequent wet processing and drying.
Solution Approach 2:
The patent changes the physical-chemical parameters of the feature surfaces by applying the protective coating, which alters the surface energy and wettability characteristics. This parameter change prevents capillary forces from causing collapse while maintaining the high aspect ratio geometry needed for high device density.
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 and repairs feature collapse by breaking bonds between adjacent features, allowing continued processing of the wafer with improved yield and reduced defects, while being more cost-effective than previous methods.
Implementation Method 1
removing oxide layer with wet etching chemistry
Implementation Method 2
feature collapse during wet chemical treatment and drying processes due to capillary forces
Implementation Method 3
repairing pattern collapse among the high aspect ratio features by performing plasma etching
Implementation Method 4
repairing pattern collapse among the multiple high aspect ratio features by performing a wet etching process. The wet etching can include an HF etch
Data Source
AI summary
A method is provided for processing a wafer used in fabricating semiconductor devices. The method can comprise forming high-aspect ratio features on the wafer, which is followed by wet processing and drying. During drying, pattern collapse can occur. This pattern collapse can be repaired to allow for additional processing of the wafer. In some instance, pattern collapse can be repaired via etching where the etching breaks bonds that can have formed during pattern collapse.