3D Memory Vertical Channel Strain via Phase-Change Core
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Solution Overview
Problem
Three-dimensional memory devices face challenges in scaling vertically due to decreased on-current in vertical semiconductor channels as the number of word lines increases, necessitating a solution to enhance mobility and strain within these channels.
Innovation Solution
A method involving an alternating stack of insulating and conductive layers with a memory opening fill structure that includes a polycrystalline core material, inducing lateral compressive and vertical tensile strains within the semiconductor channels through an anneal process, which increases charge carrier mobility and on-current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of word lines is increased to enable vertical scaling, then the storage capacity is improved, but the on-current in vertical semiconductor channels decreases
Solution Approach 1:
The patent applies parameter changes by modifying the physical and chemical state of the core material through annealing treatment. The core material undergoes phase transformation from amorphous to crystalline state, changing its density and volume, which in turn induces mechanical strain in the semiconductor channel to improve carrier mobility and on-current
Solution Approach 2:
The patent utilizes phase transitions of the core material during annealing. The core material transitions from an amorphous phase to a crystalline phase, causing volume expansion that generates lateral compressive strain and vertical tensile strain in the semiconductor channel, thereby enhancing carrier mobility without increasing word line count
2Quantity of substance
If the number of word lines is increased to enable vertical scaling, then the storage capacity is improved, but the charge carrier mobility in vertical semiconductor channels decreases
Solution Approach 1:
The patent changes the physical parameters of the core material through annealing, transforming it from amorphous to crystalline state. This parameter change causes volume expansion that induces mechanical strain in the semiconductor channel, improving charge carrier mobility through strain-induced band structure modification
Solution Approach 2:
The patent exploits thermal expansion during the annealing process. The core material undergoes thermal expansion as it transitions from amorphous to crystalline state, generating lateral compressive strain and vertical tensile strain in the semiconductor channel, which enhances charge carrier mobility through strain engineering
3Reliability
If an anneal process is performed to induce volume expansion in core material, then the lateral compressive strain and vertical tensile strain in semiconductor channels are improved, but the manufacturing process complexity increases
Solution Approach 1:
The patent merges multiple functions into the annealing process. The same annealing step that activates dopants also induces phase transformation in the core material, causing volume expansion and strain generation in the semiconductor channel. This consolidation reduces the number of separate process steps despite the added complexity of the anneal itself
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 solution effectively enhances the mobility of vertical semiconductor channels, enabling vertical scaling of three-dimensional memory devices by increasing the number of word lines and improving on-current performance.
Implementation Method 1
inducing a volume expansion in the core material by performing an anneal process that induces a microstructural change within the core material
Implementation Method 2
the volume expansion in the core material induces a lateral compressive strain and a vertical tensile strain within the vertical semiconductor channel
Data Source
AI summary
A combination of an alternating stack and a memory opening fill structure is provided over a substrate. The alternating stack includes insulating layers and electrically conductive layers. The memory opening fill structure vertically extends through the alternating stack, and includes a memory film, a vertical semiconductor channel, and a core structure comprising a core material. A phase change material is employed for the core material. A volume expansion is induced in the core material by performing an anneal process that induces a microstructural change within the core material. The volume expansion in the core material induces a lateral compressive strain and a vertical tensile strain within the vertical semiconductor channel. The vertical tensile strain enhances charge mobility in the vertical semiconductor channel, and increases the on-current of the vertical semiconductor channel.