Metal Oxide Etch Stop Layers for Precise 3D Memory Staircases
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Solution Overview
Problem
Current three-dimensional memory devices face challenges in forming efficient etch stop layers for vertical NAND strings, particularly in effectively etching transition-metal oxides, which are crucial for precise structure formation and memory array development.
Innovation Solution
Incorporating transition-metal oxide etch stop layers, such as hafnium oxide or zirconium oxide, during the anisotropic etch process to create stepped surfaces and memory openings, allowing for precise formation of memory films and semiconductor channels within the three-dimensional memory device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etch stop layers are used in three-dimensional memory devices, then the etching process can proceed, but the selectivity and precision of etching transition-metal oxides is insufficient
Solution Approach 1:
The patent changes the material parameter of the etch stop layer from conventional materials to transition-metal oxides (hafnium oxide, zirconium oxide), which have different etching characteristics. This material parameter change enables selective etching with fluorine-based chemistries, achieving both precision and reliability in the etching process.
Solution Approach 2:
The patent employs composite material structures where transition-metal oxide etch stop layers are integrated within alternating stacks of insulating and conductive layers. This composite approach allows the etch stop layer to work synergistically with the surrounding materials, providing precise etching control while maintaining structural integrity.
2Manufacturing precision
If transition-metal oxide etch stop layers are incorporated, then etching selectivity and precision improve, but the device structure becomes more complex
Solution Approach 1:
The transition-metal oxide etch stop layers serve multiple functions: they act as etch stop layers during fluorine-based anisotropic etching, provide structural support within the alternating stacks, and enable precise formation of memory openings and contact via structures. This multi-functionality reduces the need for additional separate components.
Solution Approach 2:
The patent segments the alternating stacks by inserting transition-metal oxide etch stop layers between insulating and conductive layers. This segmentation creates distinct functional zones that can be selectively etched, improving precision while organizing the complex structure into manageable segments.
3Manufacturing precision
If fluorine-based anisotropic etching is used through transition-metal oxide layers, then precise memory openings are formed, but the etching process becomes more difficult to control
Solution Approach 1:
The transition-metal oxide etch stop layers act as intermediary layers that mediate between the fluorine-based etching chemistry and the underlying structures. These layers provide a controlled interface that enables precise etching while protecting surrounding materials, making the overall process more manageable despite the complexity of fluorine-based chemistry.
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 enables precise control over the etching process, improving the structural integrity and memory performance of three-dimensional memory devices by providing effective etch stop functionality and enhancing the selectivity of etching chemistries.
Implementation Method 1
by performing a fluorine-based anisotropic etch through the stepped dielectric material portion
Implementation Method 2
by performing a chlorine-based anisotropic etch through the at least one transition-metal oxide etch stop layer
Data Source
AI summary
A semiconductor structure includes an alternating stack of first insulating layers and first electrically conductive layers, the first alternating stack having first stepped surfaces, at least one first metal oxide etch stop layer overlying and contacting the first stepped surfaces, a first stepped dielectric material portion overlying the at least one first metal oxide etch stop layer and the first stepped surfaces, a memory opening vertically extending through the first alternating stack, a memory opening fill structure located in the memory opening and containing a memory film and a vertical semiconductor channel, and an electrically conductive layer contact via structure vertically extending through the first stepped dielectric material portion and the at least one first metal oxide etch stop layer, and contacting a respective one of the first electrically conductive layers.