Nitrogen Pocket Implant Passivation for Non-Volatile Memory Retention
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Solution Overview
Problem
Conventional non-volatile memory devices, such as nitride read-only memory devices, experience performance degradation due to increased interface trap density caused by cycling, leading to threshold voltage shifts and reduced data retention, especially in high temperature environments.
Innovation Solution
Implementing nitrogen-doped regions around the source/drain areas to passivate the interface between the substrate and the charge trapping structure, using nitrogen implantation followed by annealing to reduce interface traps and enhance the oxide-substrate interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional nitride read-only memory structures are cycled for programming and erasing, then the memory device can perform multiple write operations, but interface trap density increases causing threshold voltage shifts and reduced data retention
Solution Approach 1:
The patent applies preliminary action by performing nitrogen implantation into the oxide layer before the memory device undergoes programming and erasing cycles. This pre-treatment passivates interface traps in advance, preventing the degradation that would normally occur during cycling. The nitrogen atoms are introduced at a dose of 1×10^19 to 1×10^21 atoms/cm², creating a buffer that stabilizes the interface before operational stress is applied.
Solution Approach 2:
The patent changes the chemical composition parameter of the oxide layer by introducing nitrogen atoms through implantation. This parameter change transforms the oxide layer from a vulnerable interface prone to trap formation into a stabilized structure with reduced interface trap density. The nitrogen concentration is controlled within specific ranges to achieve optimal passivation without compromising other device characteristics.
2Reliability
If high temperature baking is applied to anneal interface traps, then short-term threshold voltage stability may improve, but long-term data retention degrades due to enhanced trap activity
Solution Approach 1:
The patent converts the normally harmful effect of high temperature (which activates interface traps and degrades data retention) into a beneficial process. By performing nitrogen implantation first, the subsequent high temperature baking anneals the implantation damage and activates the nitrogen atoms for effective passivation. The nitrogen atoms, now activated by heat, bond with interface states to reduce trap density, transforming the harmful thermal effect into a useful annealing process that improves both threshold voltage stability and long-term 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 nitrogen passivation significantly improves data retention and performance of cycled non-volatile memory devices by reducing interface trap density and enhancing the reliability of nitride read-only memory devices.
Implementation Method 1
the interface between the substrate and the charge trapping structure above the nitrogen-doped region is passivated by a plurality of nitrogen atoms
Implementation Method 2
nitrogen implantation followed by annealing to reduce interface traps and enhance the oxide-substrate interface
Implementation Method 3
nitrogen implantation followed by annealing to reduce interface traps and enhance the oxide-substrate interface
Data Source
AI summary
In a non-volatile memory structure, the source/drain regions are surrounded by a nitrogen-doped region. As a result, an interface between the substrate and the charge trapping layer above the nitrogen-doped region is passivated by a plurality of nitrogen atoms. The nitrogen atoms can improve data retention, and performance of cycled non-volatile memory devices.