3D Phase Change Memory Array Without Diodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current three-dimensional integrated circuit memory technologies require rectifiers or diodes at each memory cell, complicating manufacturing and increasing costs, while seeking to achieve higher storage capacity and lower costs per bit.
Innovation Solution
A 3D phase change memory device using phase change material with different amorphous phase thicknesses to represent data, eliminating the need for additional access devices like diodes, and employing programming pulses to establish non-overlapping resistance ranges for data storage across multiple conductive layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If rectifiers or diodes are used at each memory cell to enable 3D memory structure, then storage capacity and integration density are improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts and removes the rectifier/diode component from each memory cell intersection. Instead of requiring four access devices per cell (two transistors plus two diodes/rectifiers), the invention uses only transistor access devices, eliminating the need for diode fabrication and reducing manufacturing complexity while maintaining the 3D stacked memory structure
Solution Approach 2:
The patent makes the transistor access devices perform multiple functions. The transistors serve both as access switches and as the primary selective element, replacing the need for separate diode-based rectification functions. This multi-functionality reduces the total component count and simplifies the cell structure
2Quantity of substance
If rectifiers or diodes are used at each memory cell to enable 3D memory structure, then storage capacity and integration density are improved, but manufacturing cost increases
Solution Approach 1:
The patent extracts and removes the rectifier/diode component from each memory cell intersection. Instead of requiring four access devices per cell (two transistors plus two diodes/rectifiers), the invention uses only transistor access devices, eliminating the need for diode fabrication and reducing manufacturing complexity while maintaining the 3D stacked memory structure
Solution Approach 2:
The patent changes the material and structural parameters of the access devices. By using standard transistor structures with configurable threshold voltages rather than requiring specialized diode materials and structures, the manufacturing process becomes more compatible with standard CMOS fabrication, reducing overall manufacturing cost
3Device complexity
If phase change material with different amorphous phase thicknesses is used to represent data, then manufacturing complexity is reduced and cost decreases, but achieving precise resistance ranges becomes more difficult
Solution Approach 1:
The patent implements feedback control in the programming process. The system reads the current resistance state of the memory cell and uses this information to determine the appropriate programming pulse parameters. This feedback loop enables precise control of the amorphous phase thickness and resulting resistance range, achieving the desired manufacturing precision without requiring extremely tight process control
Solution Approach 2:
The patent uses dynamic programming pulses with varying amplitude and duration. Rather than relying on static material properties alone, the system dynamically adjusts the programming parameters to achieve the target resistance ranges. This dynamic approach allows flexible control over the amorphous phase thickness and resulting resistance characteristics
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 solution simplifies the manufacturing process, reduces costs, and enables high-density storage by using phase change material resistance states to represent data without additional access devices, maintaining high reliability and low leakage current.
Implementation Method 1
phase change memory material in an interface between the first and second conductors, wherein data stored in the memory cell is represented only by different non-zero thicknesses in an amorphous phase of the phase change memory material
Implementation Method 2
applying a programming pulse through the selected phase change memory cell, the current pulse being configured to program data in the memory cells
Data Source
AI summary
A 3D phase change memory device can store multiple bits per cell represented by a plurality of non-overlapping ranges of resistance all of which are established by different resistance ranges corresponding to respective amorphous phase thickness of the phase change memory material. An array of access devices can underlie a plurality of conductive layers, separated from each other and from the array of access devices by insulating layers. An array of pillars extending through the plurality of conductive layers contact corresponding access devices. The phase memory material is between the pillars and conductive layers. Circuitry is configured to program data in the memory cells using programming pulses having shapes that depend on the resistance range of the cell before programming and the data values to be stored.