RRAM Memory Cell Buffer Layer Structure for Reset Current Control
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Solution Overview
Problem
Resistive random access memory (RRAM) devices using a single metal electrode face issues with excessive first time reset current and high forming voltage, particularly when using metals that are difficult to react with oxides, which affect the reliability and efficiency of memory operations.
Innovation Solution
A memory cell structure for RRAM is developed, featuring a metal oxide layer sandwiched between a first buffer layer that minimally reacts with oxygen and a second buffer layer that strongly reacts with oxygen, along with electrodes that block oxygen diffusion, to manage reset current and forming voltage effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single metal electrode is used as an oxygen atom absorbing layer, then the RRAM has excellent memory characteristics, but the first time reset current during current scaling process is excessive
Solution Approach 1:
The single metal electrode oxygen absorbing layer is segmented into a stacked layer structure consisting of a first metal layer and a second metal layer. The first metal layer (e.g., Ta, W, Mo) has strong oxygen affinity and is positioned adjacent to the metal oxide layer, while the second metal layer (e.g., Pt, Pd, Ir) has weak oxygen affinity and is positioned adjacent to the first electrode. This segmentation allows the first metal layer to control oxygen diffusion and suppress reset current, while the second metal layer provides good electrical contact and stability.
Solution Approach 2:
Different regions of the oxygen absorbing layer are assigned different material properties: the first metal layer near the metal oxide layer uses materials with high oxygen affinity to locally suppress oxygen diffusion and reduce reset current, while the second metal layer near the first electrode uses materials with low oxygen affinity to maintain good electrical contact and stability. This local quality differentiation resolves the contradiction between suppressing harmful reset current and maintaining excellent memory characteristics.
2Object-generated harmful factors
If a metal that is difficult to react with oxide is used in the RRAM, then the problem of excessive first time reset current is overcome, but the forming voltage is large
Solution Approach 1:
The oxygen absorbing layer is segmented into two functional metal layers: the first metal layer (Ta, W, Mo) with strong oxygen affinity positioned near the metal oxide layer to enable low forming voltage through controlled oxygen interaction, and the second metal layer (Pt, Pd, Ir) with weak oxygen affinity positioned near the first electrode to suppress excessive reset current. This segmentation allows simultaneous optimization of forming voltage and reset current control.
Solution Approach 2:
The first metal layer acts as an intermediary between the metal oxide layer and the second metal layer. It facilitates controlled oxygen diffusion from the metal oxide layer, enabling low forming voltage operation, while the second metal layer serves as an intermediary that provides stable electrical contact and suppresses harmful reset current. The stacked structure creates a gradient of oxygen affinity that mediates between the conflicting requirements of low forming voltage and suppressed reset current.
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 structure reduces the first time reset current and lowers the forming voltage, enhancing the reliability and efficiency of RRAM memory operations by optimizing the buffer layer interactions and electrode materials.
Implementation Method 1
the second buffer layer reacts with oxygen from the first buffer layer more strongly than the first buffer layer reacts with oxygen from the metal oxide layer
Implementation Method 2
the second buffer layer reacts with oxygen from the first buffer layer more strongly than the first buffer layer reacts with oxygen from the metal oxide layer
Implementation Method 3
electrode buffer stacked layer... to manage reset current and forming voltage effectively
Data Source
AI summary
A memory cell of a resistive random access memory and a manufacturing method thereof are provided. The method includes the following steps. A first electrode is formed. A metal oxide layer is formed on the first electrode. An electrode buffer stacked layer is formed on the metal oxide layer and includes a first buffer layer and a second buffer layer, and the first buffer layer is located between the second buffer layer and the metal oxide layer. The second buffer layer reacts with oxygen from the first buffer layer more strongly than the first buffer layer reacts with oxygen from the metal oxide layer. A second electrode layer is formed on the electrode buffer stacked layer.