ONO Stack Hydrogen Occluding Film for Memory Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor memory technologies face challenges in maintaining reliable electron trapping and threshold voltage stability due to varying hydrogen concentrations in ONO stacks, with both high and low hydrogen theories presenting conflicting requirements for device operation.
Innovation Solution
Incorporating a hydrogen occluding film, specifically a silicon oxy-nitride film with Si2N2O, at interfaces within the ONO stack to control hydrogen diffusion and concentration, thereby stabilizing electron trapping and maintaining threshold voltage consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrogen concentration in ONO stack is increased to improve electron trapping, then electron trapping capability is improved, but threshold voltage stability deteriorates
Solution Approach 1:
The patent divides the ONO stack into multiple layers with different hydrogen concentrations. The bottom oxide film contains hydrogen for electron trapping, while the top oxide film has reduced hydrogen for stability. This segmentation allows each layer to fulfill its specific function without compromising the other.
Solution Approach 2:
Different regions of the ONO stack are given different hydrogen concentrations tailored to their specific functions. The bottom oxide film near the silicon substrate has higher hydrogen content for trapping electrons, while the top oxide film has lower hydrogen content for maintaining threshold voltage stability during read operations.
2Stability of the object's composition
If hydrogen concentration in ONO stack is decreased to improve threshold voltage stability, then threshold voltage stability is improved, but electron trapping capability deteriorates
Solution Approach 1:
The patent segments the oxide films into bottom and top layers with different hydrogen concentrations. The bottom oxide film maintains high hydrogen for trapping, while the top oxide film has reduced hydrogen for stability, resolving the contradiction through spatial separation of functions.
Solution Approach 2:
Each oxide film layer is given locally optimized hydrogen concentration: the bottom layer has high hydrogen for trapping capability, while the top layer has low hydrogen for stability, allowing both requirements to be satisfied simultaneously in different locations.
3Ease of manufacture
If conventional ONO stack structure is used, then manufacturing process is simple, but hydrogen diffusion causes threshold voltage variation
Solution Approach 1:
The conventional single oxide film is segmented into two oxide films with different hydrogen concentrations. This maintains manufacturing simplicity while the bottom oxide film traps hydrogen and the top oxide film prevents its diffusion, solving the threshold voltage variation problem.
Solution Approach 2:
The bottom oxide film acts as an intermediary that traps hydrogen, while the top oxide film serves as a barrier that prevents hydrogen diffusion to the gate electrode. This intermediary structure maintains manufacturing simplicity while ensuring threshold voltage consistency.
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 effectively blocks hydrogen diffusion, stabilizes electron trapping, and reduces variations in threshold voltage, enhancing the reliability and durability of semiconductor memory devices by immobilizing hydrogen at interfaces, thus improving data retention and operational stability.
Implementation Method 1
Incorporating a hydrogen occluding film, specifically a silicon oxy-nitride film with Si2N2O, at interfaces within the ONO stack to control hydrogen diffusion and concentration
Implementation Method 2
an ONO stack (a silicon oxide film/a silicon nitride film/a silicon oxide film), capable of trapping electrical charges
Data Source
AI summary
A semiconductor memory in which a gate insulating film (tunnel insulating film) in a memory cell provides higher operational reliability. The semiconductor memory includes an insulating film 3 between a silicon substrate 1 and a gate electrode 4. The insulating film 3 is composed of a silicon oxide film 3f, a silicon nitride film 3d and a silicon oxide film 3b, stacked in this order between the silicon substrate and the gate electrode from the side of the silicon substrate 1. There are provided hydrogen occluding films 3a, 3c and 3e on an interface between the silicon oxide film 3f and the silicon nitride film 3d, on an interface between the silicon nitride film 3d and the silicon oxide film 3b and on an interface between the silicon oxide film 3b and the gate electrode 4 (FIGS. 1A and 1B).