IGZO 3D Flash Memory Drain Junction Contact Resistance
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Solution Overview
Problem
Three-dimensional flash memory using indium gallium zinc oxide (IGZO) channel layers faces high contact resistance issues, which limits the area of the drain junction and affects leakage current characteristics.
Innovation Solution
A double-structured drain junction is implemented, with a first area N+ doped in the channel layer and a second area doped with a material having lower contact resistance, such as polysilicon, to increase the contact area and reduce resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If IGZO material is used for the channel layer to achieve excellent leakage current characteristics, then leakage current is suppressed, but contact resistance increases
Solution Approach 1:
The drain junction is divided into two distinct regions: a first region with N+ doping in the IGZO channel layer and a second region with polysilicon material. This segmentation allows each region to optimize for its specific function - the first region maintains the low leakage current characteristic of IGZO while the second region provides low contact resistance through polysilicon
Solution Approach 2:
Different materials and doping concentrations are applied to different local regions of the drain junction. The first area uses N+ doped IGZO for low leakage, while the second area uses polysilicon for low contact resistance. This local differentiation resolves the contradiction by allowing each region to have the optimal properties for its specific function
2Reliability
If the drain junction area is increased to reduce contact resistance, then contact resistance improves, but the structure becomes more complex
Solution Approach 1:
The two drain junction regions are merged into a single integrated structure where the polysilicon second area is formed within or adjacent to the N+ doped first area. This merging approach increases the effective contact area to reduce contact resistance while avoiding the need for separate, complex structures
Solution Approach 2:
The second polysilicon area is formed within or nested adjacent to the first N+ doped area, creating a compact double-structured drain junction. This nesting approach maximizes the use of available space and increases contact area without proportionally increasing overall structural complexity
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 enhanced drain junction structure maximizes the contact area, improving the contact resistance of the channel layer and suppressing leakage current, thereby enhancing the performance of the three-dimensional flash memory.
Implementation Method 1
a first area N+ doped in the channel layer and a second area N+ doped with a material having a smaller contact resistance than that of the channel layer
Data Source
AI summary
Disclosed are a three-dimensional flash memory for improving contact resistance of IGZO channel layer and a method for manufacturing same. According to one embodiment, the three-dimensional flash memory may comprise: multiple word lines sequentially stacked and extending in a horizontal direction on a substrate; and at least one string extending in a vertical direction on the substrate through the multiple word lines, the at least one string comprising a channel layer extending in the vertical direction and a charge storage layer formed to surround the channel layer, wherein the at least one string comprises a drain junction formed in a dual structure and comprising an N+ doped first area on the channel layer and an N+ doped second area with a material having lower contact resistance than the channel layer.