Phase Change Memory Fabrication via Orthogonal Mold Segmentation
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Solution Overview
Problem
The increasing complexity and size of semiconductor memory devices lead to higher wordline and bitline capacitances, limiting their speed and power consumption, necessitating the development of next-generation memory devices like phase change random access memory (PRAM) with improved electrical characteristics and process margins.
Innovation Solution
A method for fabricating phase change memory devices involves forming bottom electrodes, mold layers, and phase change material layers in specific configurations to reduce contact areas and volumes, minimizing misalignment and power consumption, and enhancing endurance characteristics through precise trench formation and planarization processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory cells are increased in number and decreased in size to achieve higher integration, then device density is improved, but wordline and bitline capacitances increase leading to higher power consumption and reduced speed
Solution Approach 1:
The patent segments the phase change material layer into multiple isolated phase change layers, each connected to individual bottom electrodes. This segmentation reduces the total contact area between electrodes and phase change material, thereby reducing the capacitance and power consumption while maintaining high cell density
Solution Approach 2:
The patent introduces orthogonal mold layers (first mold layer extending in first direction, second mold layer extending in second direction orthogonal to first direction) to create three-dimensional isolation structures. This dimensional approach enables precise control of phase change layer formation and reduces overlapping capacitance effects
2Reliability
If phase change material layer is formed to connect to parts of bottom electrodes, then electrical connection is achieved, but misalignment and dispersion of operating current occur
Solution Approach 1:
The patent forms mold layers and trenches before forming the phase change material layer, establishing precise geometric boundaries in advance. This preliminary structuring ensures that when the phase change material is deposited, it automatically aligns with the bottom electrodes through the pre-defined trench configurations, reducing misalignment and current dispersion
Solution Approach 2:
The patent creates localized phase change layers within orthogonally oriented trenches, ensuring that each phase change layer makes contact only with its designated bottom electrode portions. This localized configuration minimizes current path dispersion and improves alignment precision by confining the electrical connection to specific regions
Data Source
AI summary
Provided is a method for fabricating a phase change memory device. The method includes forming a plurality of bottom electrodes on a substrate, forming a first mold layer on the substrate to extend in a first direction where the bottom electrodes are exposed, forming a second mold layer on the substrate, the second mold layer extending in a second direction orthogonal to the first direction to expose parts of the bottom electrodes, forming a phase change material layer on the first and second mold layers to be connected to parts of the bottom electrodes dividing the phase change material layer as a plurality of phase change layers respectively connected to the parts of the bottom electrodes and forming a plurality of top electrodes on the phase change layers.