Columnar Storage Node Fabrication via Ion Implantation Hard Mask
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Solution Overview
Problem
The existing methods for fabricating storage nodes in DRAM devices face instability due to high aspect ratio openings with tapered sidewall profiles, leading to the storage node bridge phenomenon and device failure.
Innovation Solution
A method involving a stacked structure with a supporting layer and spacer layer, where ion implantation is used to form a hard mask for selective etching, allowing for the formation of columnar storage nodes with improved stability by controlling the etching process and preventing the storage node bridge phenomenon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the height of storage node is increased to increase surface area, then the capacity of capacitor is improved, but the stability of storage node structure deteriorates
Solution Approach 1:
The storage node structure is segmented into multiple functional layers: a supporting layer (first dielectric layer) that provides structural foundation, a storage node layer formed on sidewalls and bottom of openings, and a second dielectric layer. This segmentation allows the supporting layer to bear the structural load while the storage node layer provides capacitive function, resolving the contradiction between height increase for capacity and structural stability.
Solution Approach 2:
A spacer layer is introduced as an intermediary component between the storage node layer and the second dielectric layer. The spacer layer provides mechanical support and spacing, acting as a mediator that enhances structural stability while allowing the storage node to maintain its required height for sufficient surface area and capacitance.
2Productivity
If high aspect ratio openings are etched to form storage nodes, then the integration level is improved, but the sidewall profile becomes tapered leading to storage node bridge phenomenon
Solution Approach 1:
The supporting layer is formed in advance before etching the high aspect ratio openings. This preliminary action provides a structural foundation that prevents tapering during the etching process, allowing straight sidewall profiles to be maintained even when etching deep openings for high integration density.
Solution Approach 2:
The spacer layer serves as an intermediary that maintains spacing and prevents the storage node bridge phenomenon. By providing a physical barrier and structural support during and after etching, the spacer layer ensures precise sidewall profiles are maintained throughout the manufacturing process.
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 stability of the storage node structure, preventing the storage node bridge phenomenon and ensuring reliable DRAM device operation by maintaining a consistent and stable structure.
Implementation Method 1
performing an ion implantation process to implant dopants into portions of the spacer layer
Data Source
AI summary
A method of fabricating a storage node with a supported structure is provided. A dielectric stacked comprising an etch stop layer, a first dielectric layer, a support layer and a second dielectric layer is formed on a substrate. An opening is etched into the dielectric stacked. A conductive layer is formed on the second dielectric layer and inside the opening. The conductive layer directly above the second dielectric layer is removed to form columnar node structure. The second dielectric layer is then removed. A spacer layer is deposited on the support layer and the columnar node structure. A tilt-angle implant is performed to implant dopants into the spacer layer. The undoped spacer layer is removed to form a hard mask. The support layer not covered by the hard mask is etched away to expose the first dielectric layer. The first dielectric layer and the hard mask are removed.