3D Memory Drain Contact Via Etch-Stop Layer for Precise Etching
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Solution Overview
Problem
Existing three-dimensional memory devices face challenges in efficiently forming drain contact via structures due to the complexity of etching processes, which can lead to inaccuracies and structural integrity issues.
Innovation Solution
Incorporation of an etch-stop dielectric layer in the drain contact via structures, combined with a method of forming an alternating stack of insulating and sacrificial material layers, allows for precise etching and formation of memory openings and fill structures, ensuring structural integrity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional etching processes are used for drain contact via structures, then the manufacturing process is simpler, but the etching precision and structural integrity deteriorate
Solution Approach 1:
An etch-stop dielectric layer is introduced as an intermediary layer between the insulating cap layer and the alternating stack. This layer serves as a precise stopping point during etching operations, enabling accurate formation of drain contact via structures without requiring complex multi-step etching processes. The etch-stop layer has distinct etching characteristics that allow it to be selectively removed or stopped upon, providing precise depth control.
Solution Approach 2:
The etch-stop dielectric layer is formed in advance before the drain contact via etching process. This preliminary action establishes a predetermined stopping point that guides the etching depth, ensuring that the via structures are formed with precise depth control without needing complex real-time monitoring or multiple etching steps.
2Manufacturing precision
If complex etching processes are used to improve precision, then the etching accuracy improves, but the manufacturing time and process complexity increase
Solution Approach 1:
The etch-stop dielectric layer acts as a physical mediator that provides an automatic stopping mechanism during etching. This eliminates the need for complex multi-step etching processes with multiple masks and etch conditions, reducing manufacturing time while maintaining high precision. The etch-stop layer is designed to be selectively removable or to provide a clear etching termination point.
Solution Approach 2:
The etch-stop dielectric layer has specifically selected material parameters (etching rate, selectivity) that differ from surrounding layers. This parameter change enables simple, single-step etching processes to achieve precise depth control, as the etch process naturally stops or slows significantly when encountering the etch-stop layer, reducing overall manufacturing time.
3Reliability
If traditional via formation methods are used, then the process is faster, but the structural integrity and accuracy of drain contact via structures deteriorate
Solution Approach 1:
The etch-stop dielectric layer serves as a protective intermediary that defines the precise boundary for via formation. It prevents over-etching into the alternating stack and ensures that vias are formed with accurate depth and positioning, thereby improving structural integrity without significantly impacting formation speed.
Solution Approach 2:
The etch-stop layer is prepared in advance as part of the stack structure, so that during via formation, the etching process automatically achieves the correct depth without requiring additional stopping or monitoring steps. This preliminary preparation maintains high productivity while ensuring reliable structural integrity.
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
The etch-stop dielectric layer facilitates precise etching, enhancing the structural integrity and accuracy of drain contact via structures in three-dimensional memory devices, thereby improving device performance and reliability.
Implementation Method 1
an etch-stop dielectric layer for drain contact via structures
Data Source
AI summary
A three-dimensional memory device includes an alternating stack of insulating layers and electrically conductive layers, a composite insulating cap layer located over the alternating stack, memory openings vertically extending through the composite insulating cap layer and the alternating stack, and memory opening fill structures located in the memory openings. Each of the memory opening fill structures includes a vertical semiconductor channel and a vertical stack of memory elements. The composite insulating layer includes a bottom insulating cap layer, a top insulating cap layer, and an etch-stop dielectric layer located between the bottom insulating cap layer and the top insulating cap layer.