Sidewall Electrode Phase Change Memory Drive Current Reduction
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Solution Overview
Problem
Conventional phase change random access memory (PCRAM) devices face challenges in minimizing the drive current due to the large contact area between electrodes and the phase change material, which is difficult to achieve with existing photo-etching technologies.
Innovation Solution
The implementation of sidewall electrodes in contact with the phase change material, reducing the contact area and utilizing a fabrication process that integrates with the VIA-LOOP process, allowing for a smaller contact area without the limitations of photo-etching, using materials like GeSbTe for the phase change material and titanium nitride for the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional photo-etching technology is used to form electrodes, then the manufacturing process is simple, but the contact area between electrode and phase change material is large
Solution Approach 1:
The patent transitions from planar top/bottom electrode contact to three-dimensional sidewall electrode contact. The sidewall electrodes are formed on the lateral surfaces of the phase change material layer, utilizing the vertical dimension to achieve contact area reduction while maintaining electrical connection functionality.
Solution Approach 2:
The single bottom electrode contact is segmented into multiple sidewall electrodes positioned at different lateral locations. This segmentation allows the total contact area to be distributed across multiple smaller contact points, reducing the overall contact area while maintaining sufficient electrical connection.
2Use of energy by moving object
If the contact area between electrode and phase change material is reduced, then the drive current is reduced, but the manufacturing precision requirement increases
Solution Approach 1:
The patent replaces the photo-etching process with a self-aligned deposition and etching process. The sidewall electrodes are formed by depositing conductive material on the sidewalls of the phase change material layer, followed by anisotropic etching. This process inherently provides better dimensional control and alignment precision compared to conventional photo-etching.
Solution Approach 2:
The patent changes the geometric parameters of the contact structure from planar to three-dimensional sidewall contact. By controlling the height, thickness, and position of the sidewall electrodes, the contact area can be precisely adjusted to achieve the desired drive current level while maintaining manufacturing feasibility.
3Use of energy by moving object
If sidewall electrodes are used instead of top/bottom electrodes, then the contact area is reduced and drive current is lowered, but the device complexity increases
Solution Approach 1:
The sidewall electrodes serve multiple functions: they provide electrical connection to the phase change material, define the contact area for current control, and act as alignment references for subsequent processing steps. This multi-functionality reduces the need for additional separate structures, offsetting the increased structural complexity.
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 effectively reduces the drive current required to change the phase of the phase change material, meeting stringent integration requirements by minimizing the contact area between electrodes and the phase change material, enhancing the efficiency of PCRAM devices.
Implementation Method 1
The phase change material layer has a relatively low resistance when the phase change material layer is in a crystalline phase, and has a relatively high resistance when the phase change material layer is in an amorphous phase
Implementation Method 2
a first sidewall electrode and a second sidewall electrode which are respectively located on two opposite sidewalls of the phase change unit and respectively in contact with two opposite end faces of the phase change material layer
Data Source
AI summary
A device that may be used for a phase change random access memory in a semiconductor device and a manufacturing method thereof are provided. The device includes a phase change unit and two sidewall electrodes respectively located on two opposite sidewalls of the phase change unit. The phase change unit includes a three layer structure, in which a phase change material layer is positioned between a top insulating material layer and a bottom insulating material layer. The first sidewall electrode and the second sidewall electrode are in contact with two opposite end faces of the phase change material layer. The contact area between electrode and phase change material is reduced, thereby obtaining a relatively small drive current and meeting a demand that the integrated level of such a device is increasingly enhanced.