Vertical Channel Nonvolatile Memory Doping Control
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Solution Overview
Problem
Conventional methods for fabricating 3D nonvolatile memory devices face challenges in controlling the doping concentration of vertical channels, making it difficult to achieve low doping concentrations necessary for optimal threshold voltage control.
Innovation Solution
A method involving the alternation of interlayer insulating and gate electrode layers to form a channel trench, followed by the deposition of undoped and doped channel layers using plasma doping and thermal treatment to achieve specific doping concentrations, allowing for the formation of channels with controlled doping levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion implantation process is used to dope the channel layer, then doping can be performed, but low doping concentration (less than 1E19 atoms/cm3) cannot be achieved
Solution Approach 1:
The patent changes the doping method from ion implantation to in-situ doping during channel layer formation. This parameter change enables precise control of doping concentration, achieving low doping concentrations (less than 1E19 atoms/cm3) that are essential for vertical channel nonvolatile memory devices with threshold voltages below 1V.
2Productivity
If the channel trench is filled with channel layer to form vertical channel, then 3D nonvolatile memory device is formed, but doping concentration control becomes difficult
Solution Approach 1:
The patent applies preliminary doping action by incorporating dopants directly into the channel layer during its formation process, before the channel trench is completely filled. This preliminary doping enables precise concentration control while maintaining the vertical channel structure necessary for high integration density.
Solution Approach 2:
The patent introduces asymmetric doping by forming channel layers with different doping concentrations at different positions or times. This asymmetric approach allows optimization of threshold voltage and performance characteristics while achieving the required low doping concentrations for vertical channel devices.
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
Enables precise control over the doping concentration of channels in 3D nonvolatile memory devices, facilitating the fabrication of memory cells with desired threshold voltages and improving integration density.
Implementation Method 1
doping the first channel layer with impurities through a plasma doping process
Implementation Method 2
doping the first channel layer with impurities through a plasma doping process; and filling the channel trench with a second channel layer
Data Source
AI summary
A method for fabricating a vertical channel type nonvolatile memory device includes: stacking a plurality of interlayer insulating layers and a plurality of gate electrode conductive layers alternately over a substrate; etching the interlayer insulating layers and the gate electrode conductive layers to form a channel trench exposing the substrate; forming an undoped first channel layer over the resulting structure including the channel trench; doping the first channel layer with impurities through a plasma doping process; and filling the channel trench with a second channel layer.