Doped Ferroelectric Capacitor Stack for Low-Voltage Memory Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional 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 maintaining nonvolatility and high cycling endurance is crucial.
Innovation Solution
A semiconductor device with a capacitor comprising 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 data storage at ultra-low voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dielectric materials are used in DRAM capacitors, then the device can operate with simple structure, but the remnant polarization is insufficient and leakage current is high
Solution Approach 1:
The patent changes the chemical composition parameters of the capacitor dielectric by doping paraelectric HfO2 with specific metal elements (Fe, Co, Ni, Cu, Zn, Mn, Cr) to induce ferroelectricity. This parameter change transforms the material properties to achieve high remnant polarization while maintaining low leakage current, resolving the contradiction between reliability and energy loss.
Solution Approach 2:
The patent creates composite ferroelectric materials by combining HfO2 base material with dopant metals (Fe, Co, Ni, Cu, Zn, Mn, Cr) to form doped HfO2 capacitors. This composite approach leverages the benefits of both materials to achieve high remnant polarization and low leakage current simultaneously, resolving the technical contradiction.
2Area of stationary object
If the dielectric constant is increased to maintain capacitance as device footprint scales down, then the capacitor can function at smaller nodes, but the leakage current increases
Solution Approach 1:
The patent changes the dielectric material parameters by using doped HfO2 with controlled dopant concentrations to achieve the required dielectric constant without increasing leakage current. This allows the capacitor to maintain functionality at scaled-down device footprints while preventing the leakage current increase that would normally occur.
3Reliability
If ferroelectric materials are used to achieve nonvolatility, then data retention is improved, but the coercive voltage becomes too high for ultra-low voltage operation
Solution Approach 1:
The patent optimizes the chemical composition parameters of the doped HfO2 material to achieve a balance between remnant polarization and coercive voltage. By carefully selecting dopant types and concentrations, the material exhibits sufficient ferroelectricity for nonvolatile data retention while maintaining low coercive voltage for ultra-low voltage operation.
Solution Approach 2:
The patent introduces local compositional variations through doping at specific concentrations to create regions with optimized electric field distribution. This local quality enhancement allows the capacitor to achieve low coercive voltage switching while maintaining the ferroelectric properties needed for data retention.
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 high remnant polarization and low coercive voltage, ensuring reliable nonvolatile memory operations with enhanced cycling endurance and data retention over extended periods.
Implementation Method 1
the dopant is present at a concentration such that a remnant polarization of the polar layer is different than that of the base polar material without the dopant
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.