Triple Work Function Memory Cell Structure for Lower Leakage
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Solution Overview
Problem
The challenge in semiconductor technology is to increase memory cell density while reducing parasitic capacitance, which is hindered by structural limitations in traditional memory cell designs.
Innovation Solution
A semiconductor device with a lateral conductive line featuring a triple work function electrode structure, including a high work function electrode, a low work function electrode, and another low work function electrode, is used to reduce leakage current and increase memory cell density by forming a low electric field, allowing for vertical stacking of memory cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If memory cell size is reduced to increase net die, then memory device density increases, but parasitic capacitance increases and storage capacitance decreases
Solution Approach 1:
The patent applies local quality by using different work function materials at different locations within the memory cell. Specifically, the first electrode of the data storage element uses a low work function material (e.g., tungsten, work function 4.5-5.0 eV) while the second electrode uses a high work function material (e.g., platinum, work function 5.6-6.0 eV). This localized differentiation optimizes the electric field distribution specifically at the capacitor electrodes, reducing parasitic capacitance in critical regions while maintaining high density.
Solution Approach 2:
The patent employs composite materials by combining different work function materials in the data storage element electrodes. The first electrode uses a low work function material such as tungsten or molybdenum, while the second electrode uses a high work function material like platinum or iridium. This composite electrode structure creates an optimized electric field that reduces parasitic capacitance effects while maintaining the required storage capacitance, enabling higher density memory cells.
2Quantity of substance
If memory cell size is reduced, then memory device density increases, but capacitance increases (desired) while parasitic capacitance also increases (undesired)
Solution Approach 1:
The patent applies local quality by using different work function materials at different locations within the memory cell. Specifically, the first electrode of the data storage element uses a low work function material (e.g., tungsten, work function 4.5-5.0 eV) while the second electrode uses a high work function material (e.g., platinum, work function 5.6-6.0 eV). This localized differentiation optimizes the electric field distribution specifically at the capacitor electrodes, reducing parasitic capacitance in critical regions while maintaining high density.
Solution Approach 2:
The patent employs composite materials by combining different work function materials in the data storage element electrodes. The first electrode uses a low work function material such as tungsten or molybdenum, while the second electrode uses a high work function material like platinum or iridium. This composite electrode structure creates an optimized electric field that reduces parasitic capacitance effects while maintaining the required storage capacitance, enabling higher density memory cells.
3Device complexity
If conventional single work function electrode structure is used, then device structure is simple, but leakage current is high and threshold voltage is low
Solution Approach 1:
The patent applies local quality by using different work function materials at different locations within the memory cell. Specifically, the first electrode of the data storage element uses a low work function material (e.g., tungsten, work function 4.5-5.0 eV) while the second electrode uses a high work function material (e.g., platinum, work function 5.6-6.0 eV). This localized differentiation optimizes the electric field distribution specifically at the capacitor electrodes, reducing parasitic capacitance in critical regions while maintaining high density.
Solution Approach 2:
The patent employs composite materials by combining different work function materials in the data storage element electrodes. The first electrode uses a low work function material such as tungsten or molybdenum, while the second electrode uses a high work function material like platinum or iridium. This composite electrode structure creates an optimized electric field that reduces parasitic capacitance effects while maintaining the required storage capacitance, enabling higher density memory cells.
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 leakage current, enhances memory cell integration density, and lowers power consumption by creating a high threshold voltage and a low electric field, facilitating high-density device integration and efficient refresh characteristics.
Implementation Method 1
a second work function electrode disposed adjacent the vertical bit line and having a lower work function than the first work function electrode; and a third work function electrode disposed adjacent to the data storage element and having a lower work function than the first work function electrode
Implementation Method 2
forming a low electric field, thereby enhancing the threshold voltage
Data Source
AI summary
A semiconductor device includes: a lateral layer spaced apart from a lower structure and extending in a direction parallel to the lower structure; a vertical conductive line extending in a direction perpendicular to the lower structure and coupled to a first-side end of the lateral layer; a data storage element coupled to a second-side end of the lateral layer; and a lateral conductive line extending in a direction crossing the lateral layer, wherein the lateral conductive line includes: a first work function electrode; a second work function electrode disposed adjacent to the vertical conductive line and having a lower work function than the first work function electrode; and a third work function electrode disposed adjacent to the data storage element and having a lower work function than the first work function electrode.