Programmable Resistive Memory Using Junction Diode Selectors
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Solution Overview
Problem
Conventional programmable resistive devices, such as electrical fuses and phase change memory cells, require large program selectors to deliver high currents, leading to increased cell size and fabrication costs, especially when using silicided polysilicon or complex process steps.
Innovation Solution
The use of P+/N well junction diodes as program selectors in standard CMOS logic processes, which can be fabricated without additional processing steps, allowing for smaller cell sizes and reduced costs by utilizing existing CMOS infrastructure and isolations like STI or SBL.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional programmable resistive memory cells use NMOS or bipolar transistors as program selectors, then the programming function can be achieved, but the device size becomes large and fabrication process becomes complex
Solution Approach 1:
The patent replaces complex, expensive transistor-based program selectors with simple, inexpensive junction diodes. The junction diode serves as a disposable-like simple component that provides the necessary programming function without the complexity of transistors, significantly reducing device size and fabrication complexity while maintaining reliability
Solution Approach 2:
The patent extracts the essential programming function from complex transistor structures and implements it using only the diode's inherent rectifying properties. By taking out the selective conduction function from the transistor and implementing it through the diode's forward/reverse bias characteristics, the solution achieves programming capability with much simpler components
2Reliability
If conventional programmable resistive memory cells are designed with large device sizes, then programming reliability can be maintained, but manufacturing cost increases and efficiency decreases
Solution Approach 1:
The junction diode serves as a simple, inexpensive replacement for complex transistor structures. This disposable-like simplicity enables high-volume manufacturing with lower costs and higher efficiency while maintaining adequate programming reliability through the diode's inherent selective conduction properties
Solution Approach 2:
The patent changes the operational parameters by using the diode's forward voltage drop and rectifying characteristics instead of transistor gate control. This parameter change enables programming functionality with simpler components that are more suitable for high-volume, cost-effective 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 enables reliable programming of resistive devices with smaller cell sizes and lower costs, as the P+/N well diodes can efficiently manage high currents and reduce fabrication complexity, making them suitable for embedded applications.
Implementation Method 1
By turning on a program selector, the programmable resistive element can be programmed
Implementation Method 2
the resistive element can assume a first resistance state in response to a first current and can assume a second resistance state in response to a second current
Data Source
AI summary
A Programmable Resistive Device (PRD) memory that can be read under low voltage is disclosed. The PRD includes at least one Programmable Resistive Element (PRE) having one end coupled to a first supply voltage line and the other end coupled to at least one selector and at least one read selector. The read selector includes at least one read source line (SLR) and/or one read enable (ENR) coupled to a second and/or a third supply voltage lines, respectively. The read selector includes at least one MOS device built by core logic device. The PRE in the at least one PRD cells can be configured to be readable by applying voltages to the first, second, and/or the third voltage supply lines to thereby sense the PRE resistance to a logic state. The programmable resistive element can have at least one element in an OTP, MTP, floating gate device, anti-fuse, or emerging memory such as PCRAM, RRAM, or MRAM, etc.