3D Virtual Ground Memory Structure for High-Density Random Access
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Solution Overview
Problem
Existing 3D memory technologies face limitations in density and lack random access capabilities, particularly in NAND architecture, making them unsuitable for high-speed applications.
Innovation Solution
A vertical memory structure is implemented using alternating layers of insulator and word line materials with conductive pillars and insulating pillars, featuring semiconductor channels and data storage structures at cross-points, along with conductive strips for pillar selection and bit line conductors, enabling high-density and random access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If NAND architecture is used to achieve high density, then storage capacity increases, but random access capability is lost
Solution Approach 1:
The patent transitions from planar 2D memory architecture to three-dimensional stacked architecture. Multiple memory planes are stacked vertically with word lines extending through the stack, enabling simultaneous access to multiple storage locations across different planes. This vertical dimension allows random access while maintaining high density through increased storage capacity per unit area.
2Quantity of substance
If critical dimensions are shrunk to increase density, then storage capacity increases, but manufacturing precision requirements worsen
Solution Approach 1:
Instead of continuing to shrink critical dimensions in the planar direction, the patent stacks multiple memory planes vertically. This approach increases storage capacity by utilizing the vertical dimension while maintaining larger, more manufacturable critical dimensions in the lateral direction. The alternating conductive and insulating pillars provide a robust structural framework that is easier to manufacture at current precision levels.
Solution Approach 2:
The memory structure is divided into repeating units of alternating conductive and insulating pillars arranged in series. This segmentation creates a modular architecture where each unit cell can be manufactured independently with standard precision, and then replicated across multiple planes and layers to achieve high overall density without requiring extreme precision control across the entire structure.
3Quantity of substance
If vertical stacking is implemented to increase density, then storage capacity increases, but device complexity increases
Solution Approach 1:
The complex three-dimensional structure is broken down into simple, repeating units of alternating conductive and insulating pillars. Each unit cell follows the same pattern, making the overall complex structure manageable through modular repetition. This segmentation simplifies the manufacturing process by using identical fabrication steps for each layer and unit cell throughout the stack.
Solution Approach 2:
The alternating conductive and insulating pillar structure serves multiple functions simultaneously: it provides structural support, defines storage locations at cross-points, enables word line routing through the stack, and facilitates bit line connections. This multi-functionality reduces the need for additional separate components, thereby managing device complexity while achieving high density.
Data Source
AI summary
Memory devices are implemented within a vertical memory structure, comprising a stack of alternating layers of insulator material and word line material, with a series of alternating conductive pillars and insulating pillars disposed through stack. Data storage structures are disposed on inside surfaces of the layers of word line material at cross-points of the insulating pillars and the layers of word line material. Semiconductor channel material is disposed between the insulating pillars and the data storage structures at cross-points of the insulating pillars with the layers of word line material. The semiconductor channel material extends around an outside surface of the insulating pillars, contacting the adjacent conductive pillars on both sides to provide source/drain terminals.