High Aspect Ratio Feature Fabrication via Sacrificial Stack Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current semiconductor fabrication methods face challenges in forming high aspect ratio features with sufficient open margin and bowing-free structures, particularly in etching processes for three-dimensional structures, where the bottom width of the features is difficult to secure without increasing the bow width.
Innovation Solution
The method involves forming an alternating stack layer and a sacrificial stack layer with alternating oxide and nitride layers, using an amorphous carbon layer as a hard mask to etch through the sacrificial and alternating stack layers, and then removing the sacrificial stack to create high aspect ratio features with improved open margin and bowing-free profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used for three-dimensional structures, then the etching process can be completed, but the bottom width of high aspect ratio features is difficult to secure and bowing occurs
Solution Approach 1:
The patent applies preliminary action by forming a sacrificial stack layer on top of the alternating stack layer before etching. This sacrificial layer serves as a pre-positioned hard mask that maintains the open margin at the top of the structure during etching, preventing bowing and ensuring sufficient bottom width. The sacrificial layer is removed after etching to reveal the final high aspect ratio features with improved geometry.
Solution Approach 2:
The patent segments the etch target layer into two distinct parts: the alternating stack layer containing the final feature pattern and the sacrificial stack layer serving as a temporary hard mask. This segmentation allows the top portion (sacrificial layer) to provide structural support during etching while the bottom portion (alternating stack) receives the etch pattern, resolving the contradiction between maintaining top open margin and achieving sufficient bottom width.
2Length of moving object
If the height of high aspect ratio features is increased, then the three-dimensional structure capability is improved, but the open margin at the bottom becomes insufficient
Solution Approach 1:
The sacrificial stack layer is formed in advance on top of the alternating stack layer to provide a hard mask during etching. This preliminary structure maintains the open margin throughout the etching process, ensuring that even as feature height increases, the bottom width remains sufficient. The sacrificial layer acts as a temporary support that is removed after etching to reveal the final high aspect ratio features.
3Shape
If the open margin at the top is maintained, then the structural integrity is improved, but the bottom width becomes insufficient
Solution Approach 1:
The patent divides the etch target into alternating stack layer and sacrificial stack layer. The sacrificial layer at the top maintains the open margin during etching, while the alternating stack layer below receives the etch pattern. This segmentation allows the top portion to preserve structural integrity with sufficient open margin while the bottom portion achieves adequate width, resolving the contradiction between top open margin and bottom width.
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 enhances the open margin of high aspect ratio features, ensuring a sufficiently large bottom width without increasing the bow width, even as the height of the features increases, by utilizing the uppermost material of the etch target layer as a hard mask during the etching process.
Implementation Method 1
etching the sacrificial stack layer and the alternating stack layer using the amorphous carbon layer pattern as an etch barrier
Data Source
AI summary
A method for fabricating a semiconductor includes: forming an etch target layer on a substrate, wherein the etch target layer includes an alternating stack layer and a sacrificial stack layer on the alternating stack layer, and wherein the sacrificial stack layer includes the same material as the alternating stack layer; forming a hard mask pattern on the sacrificial stack layer; etching the etch target layer using the hard mask pattern as an etch barrier to form a plurality of initial high aspect ratio features, the initial high aspect ratio features penetrating through the etch target layer; and removing the hard mask pattern and the sacrificial stack layer to form a plurality of high aspect ratio features.