3D Memory Bit-Line Pillars for Thermal Management
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Solution Overview
Problem
As integrated circuits (ICs) scale down, wire performance degrades, leading to increased power consumption and reduced functionality, while 3D stacking techniques face challenges in efficiently connecting transistors and managing heat in multilayer structures.
Innovation Solution
The development of 3D NOR-P memory devices with vertically oriented bit-line pillars, metalized sources and drains, and a thermally conductive path for heat removal, along with advanced layer transfer technologies for heterogeneous integration, enabling efficient memory cell design and improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If 3D stacking techniques are used to place transistors closer together, then transistor density and performance improve, but wire performance degrades and power consumption increases
Solution Approach 1:
The patent transitions from 2D planar interconnects to 3D vertical bit-line pillars. The bit-lines extend vertically through the stacked memory layers, enabling direct vertical access to memory cells in different layers. This dimensional change reduces horizontal wire lengths and enables more efficient interconnect architecture that scales with 3D stacking.
Solution Approach 2:
The patent divides the interconnect system into vertical bit-line pillars that serve specific layers, rather than using long continuous horizontal wires. Each bit-line pillar is segmented to connect to specific memory cells in vertical stacks, reducing the total interconnect length and improving signal integrity while reducing power consumption.
2Productivity
If multiple layers of transistors are monolithically constructed, then integration density improves, but heat management becomes more difficult
Solution Approach 1:
The patent introduces dedicated thermal pathways as intermediary structures between the active memory layers and the substrate. These thermal pathways include thermal vias and conductive structures that conduct heat away from the densely packed memory layers to heat sinks in the substrate, enabling effective heat management in 3D stacked architectures.
3Speed
If vertical bit-line pillars are implemented, then wire length is reduced and performance improves, but manufacturing complexity increases
Solution Approach 1:
The patent forms the vertical bit-line pillars and channel structures using preliminary epitaxial growth and selective etching steps before final transistor fabrication. The sacrificial layer pattern and selective removal processes are designed in advance to self-align the vertical structures, reducing the need for complex subsequent alignment steps and simplifying manufacturing.
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 approach enhances memory cell performance by reducing power consumption, improving write and read speeds, and extending retention time, while allowing for scalable and cost-effective integration of memory arrays with reduced thermal issues.
Implementation Method 1
a thermal path from the bit-line pillars to an external surface of the device to remove heat
Data Source
AI summary
A 3D memory device, the device comprising: a plurality of memory cells, wherein each memory cell of said plurality of memory cells comprises at least one memory transistor, wherein each of said at least one memory transistor comprises a source, a drain, and a channel; a plurality of bit-line pillars, wherein each bit-line pillar of said plurality of bit-line pillars is directly connected to a plurality of said source or said drain, wherein said bit-line pillars are vertically oriented, wherein said channel is horizontally oriented, wherein said plurality of memory cells comprise a partially or fully metalized source, and/or, a partially or fully metalized drain, and wherein said plurality of bit-line pillars comprise a thermally conductive path from said plurality of memory cells to an external surface of said device.