3D Flash Memory Channel Heterojunction for Higher Electron Mobility
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Solution Overview
Problem
Three-dimensional flash memory technologies face challenges in achieving high electron mobility due to the low actual mobility of polycrystalline silicon channel layers, leading to degradation in memory performance and operation speed.
Innovation Solution
A double-structured channel layer is introduced, comprising a first channel layer with higher electron mobility for contact with the charge storage layer and a second channel layer with improved durability and thermal performance, potentially formed from materials like polycrystalline group 3-5 compounds or silicon germanium, and a second channel layer formed from polycrystalline silicon, with a heterojunction between them to enhance electron mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a polycrystalline silicon channel layer is used in three-dimensional flash memory, then the manufacturing process is simple and cost-effective, but the electron mobility is low leading to degraded memory performance and operation speed
Solution Approach 1:
The channel layer is divided into multiple distinct layers (first channel layer with higher electron mobility and second channel layer with improved durability). This segmentation allows each layer to be optimized for its specific function, resolving the contradiction between manufacturing simplicity and electron mobility by creating a structured multi-layer system that can be manufactured using standard processes while achieving superior performance.
Solution Approach 2:
The patent employs composite material structure by combining different materials or compositions in the channel layer (such as silicon germanium and polycrystalline silicon, or different crystalline orientations). This composite approach enables the channel layer to simultaneously achieve high electron mobility in the inversion area and adequate durability, overcoming the limitations of single-material polycrystalline silicon.
2Ease of manufacture
If the channel layer is made from a single material to simplify manufacturing, then the manufacturing process is easier, but the electron mobility and durability cannot be simultaneously optimized
Solution Approach 1:
The channel layer is segmented into functionally distinct layers: a first channel layer optimized for electron mobility (using materials like silicon germanium or specific crystalline orientations) and a second channel layer optimized for durability. This segmentation resolves the contradiction by allowing material selection to be simplified at each individual layer level while achieving superior overall performance through the combination of layers.
Solution Approach 2:
Different regions of the channel layer are assigned different material properties tailored to their specific functional requirements. The first channel layer in contact with the charge storage layer uses materials with higher electron mobility to enhance operation speed, while the second channel layer uses materials with improved durability. This local quality differentiation allows simultaneous optimization of both productivity and reliability without complicating the overall manufacturing process.
Data Source
AI summary
Disclosed are: a three-dimensional flash memory including a channel layer having a multilayer structure; and a method for manufacturing same. The channel layer has a dual structure including a first channel layer which is formed to be in contact with a charge storage layer and improves the electron mobility in an inversion region that is a contact interface with the charge storage layer, and a second channel layer formed on an inner wall of the first channel layer. Alternatively, the channel layer can have a dual structure including an outer first channel layer and a second channel layer formed on an inner wall of the first channel layer, wherein a heterojunction is formed as a junction between the first channel layer and the second channel layer.