Ferroelectric Perpendicular Electrode Cell for Low-Temperature Memory
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Solution Overview
Problem
Conventional ferroelectric memory cells require high temperature processes, limiting the use of ceramic ferroelectric materials and resulting in non-uniformity and high production costs, while ferroelectric polymer thin films with perfect hysteresis loop curves are not utilized due to incompatible processing temperatures.
Innovation Solution
A nonvolatile ferroelectric perpendicular electrode cell structure using a ferroelectric capacitor with a ferroelectric polymer thin film and a serial PN diode switch, allowing for a low temperature process and improved cell uniformity, where the ferroelectric polymer thin film is coated between perpendicular electrodes and annealed at less than 200°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ceramic ferroelectric materials (PZT, SBT) are used in conventional ferroelectric capacitors, then high residual polarization and fast data processing speed are achieved, but high temperature process (>600°C) is required which limits electrode selection and increases manufacturing complexity
Solution Approach 1:
The patent changes the material parameter from ceramic ferroelectric materials to ferroelectric polymer thin films, which enables processing at low temperatures (<200°C) while maintaining ferroelectric properties. This parameter change resolves the contradiction by allowing high reliability without requiring high temperature processes.
Solution Approach 2:
The patent uses ferroelectric polymer thin films that can be processed at low temperatures, effectively replacing expensive and complex high-temperature ceramic materials. This substitution reduces manufacturing complexity while maintaining the essential ferroelectric function for data retention.
2Reliability
If ceramic ferroelectric materials are used, then ferroelectric capacitor functionality is achieved, but uniformity in characteristics of each cell degrades which results in difficulty in improvement of yield
Solution Approach 1:
The patent changes from ceramic materials to ferroelectric polymer thin films, which exhibit better uniformity in electrical characteristics across cells. This material parameter change improves manufacturing precision while preserving the ferroelectric capacitor functionality.
3Ease of manufacture
If ferroelectric polymer thin films are used, then low temperature process (<200°C) and perfect hysteresis loop curve are achieved, but conventional ferroelectric memory cell structure does not utilize these materials due to incompatible processing temperatures
Solution Approach 1:
The patent introduces a perpendicular electrode structure that is incompatible with conventional planar cells but enables the use of low-temperature ferroelectric polymer thin films. This structural dimensionality change resolves the contradiction by creating a new cell architecture that accommodates the material's processing requirements.
Solution Approach 2:
Instead of adapting the ferroelectric material to fit the conventional cell structure, the patent inverts the approach by designing a new perpendicular electrode cell structure that is specifically optimized for ferroelectric polymer thin films, enabling low-temperature processing.
4Speed
If conventional ferroelectric memory cell structure is used, then data processing speed comparable to DRAM is achieved, but the structure does not utilize low temperature process materials which increases production cost
Solution Approach 1:
The patent changes the material parameter to ferroelectric polymer thin films that can be processed at low temperatures, reducing production costs while maintaining the fast data processing speed characteristic of ferroelectric memory.
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 reduces production costs, enhances cell uniformity, and enables high-density memory capacity by using ferroelectric polymer thin films in a low temperature process, improving the structure and productivity of ferroelectric memory cells.
Implementation Method 1
a ferroelectric film having a ferroelectric material filled in a space where the lower electrode and the upper electrode
Implementation Method 2
The serial PN diode switch, which is connected between a bit line and the ferroelectric capacitor, selectively switches a current direction between the bit line and the ferroelectric capacitor depending on voltage change
Implementation Method 3
the ferroelectric polymer thin film is coated between perpendicular electrodes and annealed at less than 200°C
Data Source
AI summary
A nonvolatile ferroelectric perpendicular electrode cell comprises a ferroelectric capacitor and a serial PN diode switch. The ferroelectric capacitor includes a word line perpendicular electrode as a first electrode and a storage perpendicular electrode as a second electrode apart at a predetermined interval from the word line perpendicular electrode to have a column type, where a ferroelectric material is filled in a space where the first electrode are separated from the second electrode. The serial PN diode switch, which is connected between a bit line and the ferroelectric capacitor, selectively switches a current direction between the bit line and the ferroelectric capacitor depending on voltage change between the bit line and the ferroelectric capacitor.