Complex Oxide Nanodots for Memory Charge Retention
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Solution Overview
Problem
Conventional nonvolatile memory technologies face challenges in charge retention due to defects in tunneling dielectric layers, leading to scaling limitations and reliability issues in memory devices.
Innovation Solution
The use of complex oxide nanodots, specifically strontium titanate (STO) nanodots with a perovskite structure, formed through alternating pulse deposition methods, provides discrete charge trapping sites that minimize charge leakage and enhance charge retention capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the tunneling dielectric layer thickness is reduced to enable vertical scaling, then programming speed increases and lower voltage operation is achieved, but charge retention capability seriously degrades
Solution Approach 1:
The charge trapping layer is segmented into discrete nanodots rather than a continuous layer. This segmentation isolates charge storage into individual confined regions, preventing charge leakage paths that would exist in thin continuous dielectric layers, thereby maintaining charge retention while enabling thin tunneling oxide for fast programming
Solution Approach 2:
The nanodots provide localized charge trapping sites with specific material properties (complex oxide composition) that create deep potential wells for charge confinement. This local quality enhancement at the nanodot sites compensates for the reduced overall dielectric thickness, maintaining charge retention capability while enabling scaling
2Length of stationary object
If conventional SONOS dielectric layers are used with thin tunneling oxide, then vertical scaling is achieved, but charge retention properties intrinsically deteriorate
Solution Approach 1:
The charge trapping layer uses composite materials (complex oxides such as SrTiO3, BaTiO3, Pb(Zr,Ti)O3) with specific perovskite crystal structures that provide superior charge confinement properties. These materials have higher dielectric constants and create deeper potential wells compared to conventional SiN, enabling reliable charge retention even with thin tunneling oxide layers
Solution Approach 2:
The invention changes the material parameters of the charge trapping layer from conventional SiN to complex oxides with higher dielectric constants and appropriate band offsets. This parameter change creates deeper charge traps and improves charge confinement, compensating for the reduced tunneling oxide thickness and maintaining charge retention capability
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 implementation of STO nanodots in charge trapping layers offers superior charge storage and retention properties, reducing the sensitivity to defects and improving the reliability of memory devices by providing localized, deep charge traps with high dielectric constants and appropriate energy band characteristics.
Implementation Method 1
a second dielectric layer comprising a material having a perovskite structure over the first dielectric layer
Implementation Method 2
complex oxide nanodots, specifically strontium titanate (STO) nanodots with a perovskite structure
Data Source
AI summary
Devices are disclosed, such as those having a memory cell. The memory cell includes an active area formed of a semiconductor material; a first dielectric over the semiconductor material; a second dielectric comprising a material having a perovskite structure over the first dielectric; a third dielectric over the second dielectric; and a gate electrode over the third dielectric.