Improper Ferroelectric Gate Stack for Transistor Drive Strength
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Solution Overview
Problem
As transistors scale down, they face challenges with short-channel effects that weaken drive strength, and capacitors have limited retention durations due to traditional materials like Hafnium Oxide and ferroelectric materials with wide negative curvature, leading to inefficient energy storage and switching.
Innovation Solution
The use of improper ferroelectric materials with narrower polarization minima and taller negative curvature attributes, such as super lattices of PbTiO3 and SrTiO3, in transistor gate stacks and capacitors to enhance electrostatics, enable transient negative capacitance, and improve retention times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If traditional ferroelectric materials with wide negative curvature are used in capacitors, then capacitance is achieved, but retention duration is limited
Solution Approach 1:
The patent changes the curvature parameter of the polarization curve by selecting materials with taller negative curvature attributes. This parameter change transforms the traditional wide-curvature ferroelectric materials into improper ferroelectric materials with narrow curvature, thereby achieving both long retention duration and reliable capacitor performance simultaneously
Solution Approach 2:
The patent employs composite material structures including super lattices of PbTiO3 and SrTiO3, or combinations of improper ferroelectric materials with high-k dielectric materials. These composite structures enable the capacitor to achieve enhanced retention duration while maintaining reliable performance through the synergistic effects of the different material components
2Productivity
If transistors are scaled down in size, then device density increases, but drive strength weakens due to short-channel effects
Solution Approach 1:
The patent changes the electrostatic parameters of the transistor gate stack by incorporating improper ferroelectric materials with taller negative curvature. This parameter change enhances the electrostatic control and drive strength of scaled-down transistors, allowing high device density to be achieved without sacrificing power performance
Solution Approach 2:
The improper ferroelectric material layer acts as an intermediary between the gate electrode and the channel in scaled-down transistors. This intermediary layer with narrow polarization minima and tall negative curvature provides enhanced electrostatic control, enabling the transistor to maintain strong drive strength even at reduced dimensions for high device density
3Ease of manufacture
If Hafnium Oxide is used in MIM capacitors, then capacitor formation is achieved, but retention is limited due to sub 10 nm thickness scaling
Solution Approach 1:
The patent replaces traditional Hafnium Oxide with composite material structures including super lattices of PbTiO3 and SrTiO3 or other improper ferroelectric materials. These composite materials achieve both ease of manufacture through standard deposition techniques and superior retention performance, overcoming the limitations of sub 10 nm Hafnium Oxide scaling
Solution Approach 2:
The patent changes the material parameters from traditional Hafnium Oxide to improper ferroelectric materials with narrower polarization minima and taller negative curvature. This parameter change enables the capacitor to achieve long retention duration while maintaining manufacturability through existing semiconductor fabrication processes
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 results in improved drive current, longer retention times, and increased storage capacity in capacitors, allowing for more energy-efficient and effective transistor and capacitor performance.
Implementation Method 1
enable transient negative capacitance
Implementation Method 2
improper ferroelectric materials with narrower polarization minima and taller negative curvature attributes
Data Source
AI summary
A capacitor is provided which comprises: a first structure comprising metal; a second structure comprising metal; and a third structure between the first and second structures, wherein the third structure comprises an improper ferroelectric material. In some embodiments, a field effect transistor (FET) is provided which comprises: a substrate; a source and drain adjacent to the substrate; and a gate stack between the source and drain, wherein the gate stack includes: a dielectric; a first structure comprising improper ferroelectric material, wherein the first structure is adjacent to the dielectric; and a second structure comprising metal, wherein the second structure is adjacent to the first structure.