Cylindrical 3D Memory Cell Layout for Low-Leakage Retention
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Solution Overview
Problem
Current planar memory cells face challenges in scaling down due to increased current leakage, power consumption, and decreased retention times, while capacitor-less one transistor memory structures require further improvement for manufacturable integration and operation.
Innovation Solution
A three-dimensional memory architecture featuring a cylindrical body surrounded by multiple gates, including a word line and plate line contacts, which form a capacitor-free multi-gate vertical 1T memory structure, enhancing data retention and reducing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If planar memory cells are scaled to smaller sizes by improving process technology, then device density is improved, but current leakage increases and retention time decreases
Solution Approach 1:
The patent transitions from planar 2D memory cell architecture to a three-dimensional vertical architecture. The cylindrical body extends in the first direction (vertical), with word line contact and plate line contact segments surrounding the insulating layer at different heights, creating a 3D structure that achieves higher device density while maintaining electrical performance through vertical stacking rather than lateral scaling
Solution Approach 2:
The plate line contact is divided into multiple plate line contact segments that surround different portions of the insulating layer along the first direction. This segmentation allows for distributed electrical contact points, improving charge retention and reducing leakage current by creating multiple controlled interfaces between the plate line and the cylindrical body
2Quantity of substance
If 1T1C DRAM structure is used to achieve high device density, then storage capacity is improved, but manufacturing difficulty increases due to process limits
Solution Approach 1:
The patent extracts and eliminates the capacitor component from the traditional 1T1C memory structure, creating a capacitor-less 1T memory structure. The cylindrical body serves as the charge storage element without requiring a separate capacitor, simplifying the manufacturing process and removing process limits associated with capacitor fabrication while maintaining storage functionality
Solution Approach 2:
The cylindrical body performs multiple functions: it serves as the channel region for transistor operation, the charge storage element (replacing the capacitor), and the structural core around which contacts are formed. This multi-functionality consolidates multiple components into a single element, reducing manufacturing complexity
3Quantity of substance
If capacitor-less one transistor memory structures are implemented to improve device density, then storage capacity is improved, but operational performance requires further optimization
Solution Approach 1:
The vertical three-dimensional architecture with cylindrical body extending in the first direction provides enhanced carrier transport paths and improved electrostatic control compared to planar structures. The vertical stacking enables faster charge injection and extraction, improving program/erase speeds and operational performance while maintaining high device density
Solution Approach 2:
The word line contact and plate line contact segments are pre-positioned to surround the insulating layer at optimized locations along the first direction. This preliminary arrangement of contacts ensures efficient electrical field distribution and carrier injection paths are established before operation, enhancing operational performance
Data Source
AI summary
Embodiments of three-dimensional memory devices are disclosed. A disclosed memory structure can comprises a memory cell, a bit line contact coupled to the memory cell, a bit line coupled to the bit line contact, a source line contact coupled to the memory cell, and a source line coupled to the source line contact. The memory cell comprises a cylindrical body having a cylindrical shape, an insulating layer surrounding the cylindrical body, a word line contact surrounding a first portion of the insulating layer, the word line contact coupled to a word line, and a plurality of plate line contact segments surrounding a second portion of the insulating layer, the plurality of plate line contact segments coupled to a common plate line.