Porous Phase-Change Memory Reducing Reset Current
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Solution Overview
Problem
Current phase-change random access memory (PRAM) technologies face challenges in reducing the reset current, which is essential for scalability and power consumption, especially given the limitations of reducing the area size of the bottom electrode contact.
Innovation Solution
A PRAM structure is developed with a porous phase-change material (PCM) layer containing nano air-pores between the top and bottom electrodes, increasing current density and reducing the reset current, achieved through the use of a porogen material like cyclodextrin, which forms nano air-pores during the fabrication process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the area size of the bottom electrode contact is reduced to increase current density, then the reset current can be reduced, but the structure of the PRAM is limited and further reduction becomes difficult
Solution Approach 1:
The patent introduces a porous phase-change material layer containing nano air-pores between the electrodes. This porous structure increases the effective current density within the PCM layer without reducing the physical contact area, thereby reducing reset current while avoiding structural limitations. The porosity allows higher current concentration in the active phase-change region.
Solution Approach 2:
The patent changes the physical and electrical parameters of the phase-change material by creating a porous structure with controlled porosity (30-70%). This parameter change increases the current density within the PCM layer, enabling lower reset currents without compromising the memory cell's functionality or requiring further reduction of contact area.
2Use of energy by moving object
If the area size of the bottom electrode contact is reduced to increase current density, then the reset current can be reduced, but the contact area for reliable electrical connection is decreased
Solution Approach 1:
The porous PCM layer acts as an intermediate structure that decouples the contact area from the current density. The top and bottom electrodes maintain sufficient contact area for reliable electrical connection, while the porous PCM layer between them provides the high current density environment needed for low reset current operation.
Solution Approach 2:
The patent applies local quality by creating a porous structure specifically in the PCM layer while keeping the electrode contact regions intact. This localized porosity concentrates the current density where needed (in the PCM) without compromising the overall electrical connection reliability between electrodes.
3Use of energy by moving object
If a porous PCM layer with nano air-pores is formed to increase current density, then the reset current is reduced, but the fabrication process complexity increases
Solution Approach 1:
The patent incorporates porogen material (such as cyclodextrin) into the PCM layer before phase-change material deposition. This preliminary action allows the porous structure to form automatically during subsequent processing steps, avoiding the need for separate pore-creation steps and simplifying the overall fabrication process.
Solution Approach 2:
The porogen material serves as an intermediary substance that templates the porous structure during fabrication. It is easily removed after forming the desired pore structure, leaving behind the porous PCM layer. This intermediary approach simplifies the creation of complex porous structures compared to direct patterning methods.
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
The porous PCM layer allows for a higher current density and reduced reset current, enabling efficient phase-change operations within the PRAM, enhancing scalability and power efficiency.
Implementation Method 1
a phase-change material such as GeSbTe is changed in its phase into crystalline and amorphous by local heat generation due to an electrical pulse
Implementation Method 2
local heat generation due to an electrical pulse
Data Source
AI summary
A PRAM and a fabricating method thereof are provided. The PRAM includes a transistor and a data storage capability. The data storage capability is connected to the transistor. The data storage includes a top electrode, a bottom electrode, and a porous PCM layer. The porous PCM layer is interposed between the top electrode and the bottom electrode.