Semiconductor Memory Device Insulating Portion Hydrogen Diffusion
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Solution Overview
Problem
Current stacked-type semiconductor memory devices face challenges in improving the electrical characteristics of memory cells, particularly in reducing electron mobility and threshold voltage variations due to trap levels in the channel region.
Innovation Solution
The semiconductor memory device incorporates a stacked body with a specific insulating portion comprising silicon oxide and silicon nitride films, which extends in the stacking direction and includes a slit structure, allowing hydrogen to diffuse and terminate dangling bonds in the polysilicon channel, thereby enhancing cell current and reducing threshold voltage variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a stacked-type semiconductor memory device is used to integrate memory cells three-dimensionally, then device density is improved, but electrical characteristics of memory cells deteriorate due to trap levels in the channel region
Solution Approach 1:
An insulating film containing silicon nitride is introduced as an intermediary layer between the channel and other structures. This silicon nitride film serves as a hydrogen source that releases hydrogen atoms to terminate dangling bonds in the polysilicon channel, thereby reducing trap levels and improving electrical characteristics while maintaining the three-dimensional stacked structure
Solution Approach 2:
The invention changes the chemical composition and structural parameters of the insulating portion by incorporating silicon nitride with specific nitrogen content. This parameter change enables the insulating film to function as a hydrogen source, transforming it from a passive insulator to an active component that modifies the electrical properties of the channel through hydrogen release
2Adaptability or versatility
If the channel region is used for memory cell operation, then memory function is achieved, but electron mobility decreases and threshold voltage varies due to dangling bonds
Solution Approach 1:
The silicon nitride-containing insulating film acts as a mediator that provides hydrogen atoms to the channel region. This hydrogen terminates dangling bonds on polysilicon surfaces, reducing trap levels and stabilizing threshold voltage while preserving the memory cell's functional operation
Solution Approach 2:
The insulating film containing silicon nitride is formed in advance during the manufacturing process, positioned to contact or be near the channel region. This preliminary placement ensures that hydrogen is available to terminate dangling bonds before the device operates, preventing threshold voltage variations from the outset
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
This configuration improves the electrical characteristics of memory cells by increasing cell current and reducing threshold voltage variations, leading to better performance and reliability in the semiconductor memory device.
Implementation Method 1
allowing hydrogen to diffuse and terminate dangling bonds in the polysilicon channel
Data Source
AI summary
According to one embodiment, a semiconductor memory device includes a substrate, a stacked body, a semiconductor portion, and an insulating portion. The insulating portion is provided in the stacked body and extends in a stacking direction and a first direction along a surface of the substrate, the first direction crossing the stacking direction. The insulating portion includes a first insulating film containing silicon oxide, a second insulating film containing silicon oxide, and a third insulating film located between the first insulating film and the second insulating film and containing silicon nitride.