Vertical Semiconductor Channel Germanium Gradient
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Solution Overview
Problem
Current three-dimensional memory devices face challenges in achieving high-density storage and efficient data retention due to limitations in the formation of vertical semiconductor channels with optimal germanium concentration and gradient profiles, which affect the mobility and retention of charge carriers.
Innovation Solution
A method of forming a three-dimensional memory device by depositing a silicon-germanium alloy layer with a germanium concentration less than 25% within memory openings, followed by an oxidation process to create a vertical semiconductor channel with a germanium concentration greater than 50%, and a silicon-germanium oxide core with a radial concentration gradient, enhancing the channel's properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a silicon-germanium alloy layer with germanium concentration less than 25% is deposited and oxidized to form a vertical semiconductor channel, then the manufacturing process is simplified and manufacturing precision is improved, but the germanium concentration in the channel becomes insufficient to achieve optimal charge carrier mobility
Solution Approach 1:
The patent applies parameter changes by controlling the germanium concentration in the silicon-germanium alloy layer to be less than 25% before oxidation. This parameter control enables the oxidation process to produce a vertical semiconductor channel with germanium concentration between 20-50%, optimizing charge carrier mobility while maintaining manufacturing precision through controlled composition gradients.
Solution Approach 2:
The patent implements local quality by creating a radial concentration gradient of germanium within the vertical semiconductor channel. The germanium concentration varies from the center to the periphery of the channel, with higher concentrations at specific radial positions, providing locally optimized electrical properties for charge carrier transport while maintaining structural integrity.
2Speed
If the germanium concentration in the vertical semiconductor channel is increased to improve charge carrier mobility, then operational speed and on-current are enhanced, but the formation process becomes more complex and difficult to control
Solution Approach 1:
The patent applies preliminary action by pre-depositing the silicon-germanium alloy layer with a controlled germanium concentration (less than 25%) before the oxidation process. This preliminary step establishes the foundation for achieving the desired germanium concentration profile (20-50%) in the final vertical semiconductor channel, simplifying the overall process by avoiding complex in-situ doping or multiple deposition steps.
Solution Approach 2:
The patent utilizes parameter changes in the oxidation process to transform the germanium concentration from the initial alloy layer (less than 25%) to the final channel structure (20-50%). By controlling oxidation conditions such as temperature, time, and atmosphere, the process achieves the target germanium concentration profile without requiring complex additional processing steps, thereby enhancing operational speed while managing device complexity.
3Reliability
If a radial concentration gradient of germanium is created in the vertical semiconductor channel to optimize electrical properties, then charge carrier mobility and retention are improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent implements local quality by creating a radial concentration gradient of germanium within the vertical semiconductor channel. The germanium concentration varies locally from the center to the periphery, with specific concentration ranges (20-50%) optimized for charge carrier retention and mobility. This local variation in composition provides enhanced electrical properties while the overall process remains manufacturable through controlled deposition and oxidation parameters.
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 approach results in improved charge carrier mobility and retention, leading to increased operational speed and on-current in vertical semiconductor channels, thereby enhancing the performance and efficiency of three-dimensional memory devices.
Implementation Method 1
performing an oxidation process on the silicon-germanium alloy layer to form a vertical semiconductor channel in an unoxidized remaining material portion of the silicon-germanium alloy layer
Data Source
AI summary
An alternating stack of insulating layers and sacrificial material layers is formed over a substrate. The sacrificial material layers are formed as, or are subsequently replaced with, electrically conductive layers. Memory openings are formed through the alternating stack. A memory film is formed within each memory openings. A silicon-germanium alloy layer including germanium at an atomic concentration less than 25% is deposited within each memory opening. An oxidation process is performed on the silicon-germanium alloy layer. A vertical semiconductor channel including an unoxidized remaining material portion of the silicon-germanium alloy layer is formed, which includes germanium at an atomic concentration greater than 50%.