Semiconductor Storage Pillar Hollow Part Immobile Charge Reduction
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Solution Overview
Problem
Current semiconductor storage devices face challenges in improving electrical characteristics due to immobile charges in oxide films, which affect threshold values and writing reliability.
Innovation Solution
The semiconductor storage device incorporates a hollow part within the channel part of the pillar, reducing immobile charges and enhancing electrical characteristics by structuring the pillar with a semiconductor material and insulating parts to improve charge storage and interconnection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxide films are used in the pillar structure, then charge storage capability is improved, but immobile charges increase causing threshold value shifts and reduced writing reliability
Solution Approach 1:
The patent extracts and removes the oxide film from the pillar structure, replacing it with a semiconductor material pillar. This elimination of the oxide film directly removes the source of immobile charges while maintaining the charge storage functionality through the semiconductor material's inherent properties.
Solution Approach 2:
The patent changes the material parameter of the pillar from oxide film to semiconductor material. This parameter change fundamentally alters the electrical characteristics, eliminating immobile charges while preserving charge storage capability through the semiconductor material's band structure and carrier properties.
2Object-generated harmful factors
If the pillar is filled with semiconductor material only, then immobile charges are reduced, but charge storage efficiency may be compromised
Solution Approach 1:
The patent employs a composite structure where a semiconductor material pillar is combined with insulating films in a laminate configuration. The semiconductor pillar provides charge storage with minimal immobile charges, while the insulating films in the laminate provide electrical isolation and structural support, creating a composite system that achieves both low immobile charges and high charge storage efficiency.
3Device complexity
If insulating films and word lines are laminated with semiconductor pillars, then device structure is improved, but electrical characteristics remain insufficient due to oxide film charges
Solution Approach 1:
The patent removes the problematic oxide film component from the laminate structure while retaining the beneficial insulating films and word lines. This extraction eliminates the harmful immobile charges that degraded electrical characteristics, allowing the laminate structure to function at its full potential with improved reliability.
Data Source
AI summary
According to one embodiment, a semiconductor storage device includes a first charge storage part, a first insulating part, a second charge storage part, a second insulating part, a first select transistor, and a hollow part. The first charge storage part is at a first position separated from a surface of a substrate by a first distance in a third direction. The first select transistor is at a second position separated from the surface of the substrate by a second distance in the third direction. The second distance is greater than the first distance. The hollow part is up to a third position in the third direction separated from the surface of the substrate by a third distance in the third direction. The third distance is greater than or equal to the first distance and shorter than or equal to the second distance.