Semiconductor Charge Storage Insulating Film Oxygen Segmentation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional charge trap type nonvolatile semiconductor memories face issues with charge migration between adjacent memory cells due to high charge trap state density in silicon nitride films, leading to degraded operation characteristics and reliability, especially as memory cell sizes are miniaturized.

Innovation Solution

A semiconductor device structure is introduced, featuring a tunnel insulating film with a charge storage insulating film having separated low and high oxygen or fluorine concentration portions, where the high concentration portion between low concentration portions reduces trap state density and inhibits charge migration, and a charge block insulating film improves control gate electrode control over the semiconductor substrate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a charge storage insulating film with high charge trap state density (silicon nitride film) is used, then charge trapping capability is improved, but charge migration between adjacent memory cells occurs

Engineering Contradiction:

Improvecharge trapping capabilityVSAvoidcharge migration

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The charge storage insulating film is designed with spatially varying oxygen concentrations: high oxygen concentration regions (low trap state density) are positioned between adjacent memory cells to prevent charge migration, while low oxygen concentration regions (high trap state density) are positioned under control gate electrodes to enhance charge trapping capability. This local differentiation resolves the contradiction by optimizing each region's function.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The charge storage insulating film is segmented into functionally distinct regions with different oxygen concentrations and trap state densities. The film is divided into inter-cell regions (high oxygen, low trap density) and intra-cell regions (low oxygen, high trap density), allowing independent optimization of charge confinement and charge storage functions.

Inventive Principle:

Principle #1Segmentation

2Area of moving object

If the distance between adjacent memory cells is decreased for miniaturization, then device integration density is improved, but charge migration between cells increases

Engineering Contradiction:

Improvememory cell sizeVSAvoidcharge migration

Core Design Contradiction:

Area of moving objectVSObject-generated harmful factors

Solution Approach 1:

The invention applies local quality differentiation within the charge storage insulating film to counteract the effects of miniaturization. By positioning high oxygen concentration regions specifically in the inter-cell areas, the design maintains charge confinement even when cell dimensions are reduced and spacing is decreased.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The high oxygen concentration portion acts as an intermediary barrier between adjacent memory cells. This intermediate region with low trap state density serves as a protective layer that prevents direct charge migration between cells, enabling closer cell spacing without compromising isolation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Speed

If a tunnel insulating film with ONO structure and silicon nitride layer is used, then tunneling efficiency is improved, but charge migration between adjacent cells occurs

Engineering Contradiction:

Improvetunneling efficiencyVSAvoidcharge migration

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

The silicon nitride-based charge storage insulating film is modified with localized oxygen concentration variations. The high oxygen concentration regions are specifically positioned to address charge migration while preserving the overall tunnel insulating film structure and its efficient charge injection characteristics.

Inventive Principle:

Principle #3Local quality

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 structure effectively prevents charge migration between memory cells, enhancing the reliability and operation characteristics of nonvolatile semiconductor memories by reducing trap state density and improving electric potential control, even at small memory cell sizes.

Implementation Method 1

charges injected into the charge storage insulating film through a tunnel insulating film are trapped in trap states in the charge storage insulating film

Methodology Applied

Scientific EffectCharge trapping:

Implementation Method 2

charges injected into the charge storage insulating film through a tunnel insulating film

Methodology Applied

Scientific EffectQuantum tunneling:

Data Source

PatentUS8278696B2Semiconductor device and method of manufacturing the same

Publication Date: 2012.10.02 KIOXIA CORP

AI summary

A semiconductor device includes a tunnel insulating film formed on a semiconductor substrate, a charge storage insulating film formed on the tunnel insulating film and including at least two separated low oxygen concentration portions and a high oxygen concentration portion positioned between the adjacent low oxygen concentration portions and having a higher oxygen concentration than the low oxygen concentration portions, a charge block insulating film formed on the charge storage insulating film, and control gate electrodes formed on the charge block insulating film and above the low oxygen concentration portions.