Manganese-Doped Perovskite Capacitor Stack for Low-Voltage Memory Switching
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Solution Overview
Problem
Current semiconductor memory technologies face challenges in achieving high remnant polarization and low coercive voltage for ultra-low voltage operation, particularly in advanced technology nodes, where conventional methods struggle to maintain nonvolatility and fast switching times.
Innovation Solution
A semiconductor device with a capacitor stack featuring a polar layer doped with a metal element from the 4d, 5d, 4f, or 5f series, integrated between crystalline conductive oxide electrodes, where the dopant concentration alters the ferroelectric switching voltage and remnant polarization, enabling efficient low-voltage switching and nonvolatile memory storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ferroelectric materials are used in capacitor structures, then nonvolatile memory storage is achieved, but the coercive voltage is too high for ultra-low voltage operation
Solution Approach 1:
The patent changes the chemical composition parameters of the ferroelectric material by doping with rare earth elements (lanthanides such as La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu) at controlled concentrations (0.1-20 atomic percent). This compositional parameter change modifies the crystal structure and electronic properties, reducing the coercive voltage from conventional high values to below 1200 mV while preserving nonvolatile storage capability
Solution Approach 2:
The patent creates a composite ferroelectric material system by combining base ferroelectric materials (such as Pb(Zr,Ti)O3, Pb1-xLaxZr1-yTiyO3, or other perovskite structures) with rare earth dopants. This composite approach leverages the strong ferroelectric properties of the base material while the rare earth dopant introduces structural modifications that reduce switching voltage requirements
2Use of energy by moving object
If dopant concentration is increased to reduce coercive voltage, then ultra-low voltage operation is enabled, but remnant polarization decreases
Solution Approach 1:
The patent optimizes the dopant concentration parameter within a specific range (0.1-20 atomic percent, preferably 1-5 atomic percent) to achieve the optimal balance between reduced coercive voltage and maintained remnant polarization. This precise parameter control ensures that enough dopant is present to reduce switching voltage below 1200 mV while not so much that the remnant polarization drops below 10 μC/cm²
Solution Approach 2:
The patent employs a feedback mechanism in the material design process where the effects of rare earth doping on both coercive voltage and remnant polarization are measured and used to adjust subsequent doping concentrations. This iterative optimization ensures that the final material composition achieves both ultra-low voltage operation and sufficient polarization for reliable data retention
3Area of stationary object
If device footprint is reduced for scaling, then higher integration density is achieved, but leakage current increases
Solution Approach 1:
The patent modifies the dielectric material parameters by incorporating rare earth-doped ferroelectric layers with optimized composition and thickness. The reduced coercive voltage enables lower operating voltages, which directly reduces leakage current according to the relationship I_leakage ∝ V^α. Additionally, the enhanced remnant polarization allows for more robust signal detection, compensating for the smaller device size
Solution Approach 2:
The patent uses composite capacitor structures combining rare earth-doped ferroelectric dielectric layers with appropriate electrode materials. This composite approach creates a capacitor design where the doped ferroelectric layer provides both the necessary electrical properties (low coercive voltage, high remnant polarization) and functions as an effective barrier against leakage current, enabling scaled device footprints without proportionally increased leakage
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
The solution achieves a ferroelectric capacitor with a remnant polarization greater than 10 μC/cm² and a coercive voltage lower than 1200 mV, ensuring reliable data retention for over 10 years at room temperature, while enabling fast switching times and low power consumption.
Implementation Method 1
a ferroelectric switching voltage of the capacitor is different from that of the capacitor having the base polar material without being doped with the dopant by more than about 100 mV
Implementation Method 2
a polar layer comprising a base polar material doped with a dopant
Implementation Method 3
stored charge in the cell capacitor may represent a logical state '1'
Data Source
AI summary
The disclosed technology generally relates to ferroelectric materials and semiconductor devices, and more particularly to semiconductor memory devices incorporating doped polar materials. In one aspect, a semiconductor device comprises a capacitor which in turn comprises a polar layer comprising a base polar material doped with a dopant. The base polar material includes one or more metal elements and one or both of oxygen or nitrogen. The dopant comprises a metal element that is different from the one or more metal elements and is present at a concentration such that a ferroelectric switching voltage of the capacitor is different from that of the capacitor having the base polar material without being doped with the dopant by more than about 100 mV. The capacitor stack additionally comprises first and second crystalline conductive oxide electrodes on opposing sides of the polar layer. The capacitor stack further comprises first and second barrier metal layers on respective ones of the first and second crystalline conductive oxide electrodes on opposing sides of the polar layer.