Stacked 1T1C Memory Cell Layout for Higher Integration Density
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Solution Overview
Problem
The challenge in semiconductor integrated circuits is to increase integration density while overcoming physical limitations and manufacturing complexity, particularly in reducing the dimensions of transistors and memory cells without compromising performance.
Innovation Solution
The implementation of a novel 1T1C memory cell with a stacked and compact configuration, where the transistor partially encloses a metal-dielectric-metal capacitor, and the arrangement of memory cells and logic devices in an overlapped relationship to enhance integration density, utilizing advanced fabrication techniques such as atomic layer deposition and chemical vapor deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional planar memory cell structures are used, then manufacturing process is simpler, but integration density is lower
Solution Approach 1:
The patent transitions from traditional planar (2D) memory cell layouts to a three-dimensional stacked configuration where the capacitor is positioned vertically above the transistor. This vertical stacking enables higher integration density by utilizing the third dimension (height) rather than only horizontal plane space, allowing more memory cells to be packed into the same chip area.
Solution Approach 2:
The transistor structure is designed to partially enclose the capacitor, creating a nested configuration where the capacitor fits within the spatial envelope defined by the transistor components. This nesting arrangement maximizes space utilization and reduces the overall footprint of each memory cell.
2Area of stationary object
If transistor and capacitor are separated in traditional layouts, then manufacturing is easier, but area footprint is larger
Solution Approach 1:
The patent merges the transistor and capacitor into a single integrated stacked structure where the capacitor is formed directly above the transistor in close proximity. This consolidation reduces the area footprint by eliminating the need for separate, dispersed transistor and capacitor regions that characterize traditional planar layouts.
Solution Approach 2:
By moving the capacitor from a horizontal arrangement to a vertical position above the transistor, the design utilizes vertical space to reduce horizontal footprint. The capacitor plates are oriented such that one plate is at the same level as the transistor gate, enabling compact integration without increasing lateral dimensions.
3Productivity
If geometry size is reduced to increase functional density, then production efficiency improves, but manufacturing complexity increases
Solution Approach 1:
The fabrication process is divided into distinct sequential stages: first forming the transistor structure, then depositing capacitor dielectric layers, followed by forming capacitor electrodes, and finally creating interconnect structures. This segmentation of the manufacturing process into modular steps makes it easier to control and scale to smaller geometries compared to attempting to fabricate entire memory cells in a single complex process.
Solution Approach 2:
The transistor structure is formed completely before any capacitor components are added. This preliminary formation of the transistor baseline simplifies subsequent capacitor fabrication steps, as the transistor structure serves as a pre-established foundation upon which capacitor layers are deposited, reducing overall process complexity despite small feature sizes.
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 allows for a significant increase in integration density by creating a more compact memory cell structure and overlapping memory cells with logic devices, thereby reducing the area footprint and improving manufacturing efficiency.
Implementation Method 1
utilizing advanced fabrication techniques such as atomic layer deposition
Implementation Method 2
utilizing advanced fabrication techniques such as atomic layer deposition and chemical vapor deposition
Data Source
AI summary
Memory cells, semiconductor devices, semiconductor stacked structures, and fabrication methods are provided. An example memory cell includes a capacitor and a transistor stacked over the capacitor in a compact configuration. The capacitor includes a floating gate, a high-k dielectric layer, and a metal gate. The metal gate extends horizontally from a first sidewall to a second sidewall and vertically from a bottom surface to a top surface. The transistor includes the metal gate and a gate dielectric layer disposed on the metal gate. The gate dielectric layer includes two side portions respectively disposed on the two sidewalls of the metal gate and, and a top portion disposed on the top surface of the metal gate. The transistor further includes two separate S/D regions respectively formed on the two side portions of the gate dielectric layer, and a channel region formed on the top portion of the gate dielectric layer.