Vertical Memory Cell With Shared MIM Capacitor Electrode
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Solution Overview
Problem
Conventional memory devices, such as DRAM, face challenges in spatial efficiency and capacitance due to the large area requirements of capacitors, which hinder density and performance.
Innovation Solution
The implementation of a memory cell design with a metal-insulator-metal (MIM) capacitor at a lower device portion and a transistor at an upper portion, self-aligned to overlap and share a metal electrode, allowing for a compact footprint and increased capacitance through engineering of the capacitor dielectric and additional metal layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional capacitor designs are used in memory devices, then the basic memory function is achieved, but the area occupied by capacitors is large, reducing spatial efficiency and density
Solution Approach 1:
The patent transitions from planar capacitor layouts to three-dimensional vertical capacitor structures. The capacitor is formed as a vertical column extending through multiple layers, utilizing the vertical dimension to increase capacitance without expanding the horizontal footprint. This dimensional change enables significant area reduction while maintaining or increasing capacitance values.
Solution Approach 2:
The patent implements nested structures where conductive layers and dielectric materials are arranged in concentric or layered patterns within the vertical capacitor structure. Multiple conductive plates are nested within each other, separated by dielectric layers, creating a compact multi-plate capacitor that maximizes capacitance within a minimal volume.
2Area of stationary object
If transistor and capacitor are separately laid out in conventional memory cells, then manufacturing is simplified, but the overall cell area is large due to spacing and alignment requirements
Solution Approach 1:
The patent merges the transistor and capacitor layouts by positioning the vertical capacitor structure directly beneath or adjacent to the transistor, sharing common contact structures and alignment references. This integration reduces the overall cell area by eliminating separate layout zones and reducing spacing requirements between active components.
Solution Approach 2:
The patent designs shared structures that serve multiple functions: the bottom electrode of the vertical capacitor also serves as a contact structure for the transistor, and common alignment markers are used for both components. This multi-functionality reduces the number of discrete structures needed and simplifies the overall layout while maintaining manufacturability.
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 configuration achieves significant density savings, potentially 10 to 20 times more efficient than conventional designs, and enables the formation of large capacitance structures, enhancing memory device performance.
Implementation Method 1
a memory cell includes a metal-insulator-metal (MIM) capacitor... the second plate is separated from the first plate by a capacitor dielectric layer
Data Source
AI summary
Embodiments herein describe techniques for a semiconductor device including a memory cell vertically above a substrate. The memory cell includes a metal-insulator-metal (MIM) capacitor at a lower device portion, and a transistor at an upper device portion above the lower device portion. The MIM capacitor includes a first plate, and a second plate separated from the first plate by a capacitor dielectric layer. The first plate includes a first group of metal contacts coupled to a metal electrode vertically above the substrate. The first group of metal contacts are within one or more metal layers above the substrate in a horizontal direction in parallel to a surface of the substrate. Furthermore, the metal electrode of the first plate of the MIM capacitor is also a source electrode of the transistor. Other embodiments may be described and/or claimed.