Air Gap Isolation Structure for Non-Volatile Memory
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Solution Overview
Problem
As integration density increases in charge trap non-volatile memory devices, cell-to-cell distance decreases, leading to memory cell errors due to cell-to-cell interference, necessitating an effective device isolation structure to suppress such interference.
Innovation Solution
The implementation of an air gap isolation structure in non-volatile memory devices, where a trench with a decreasing width and a corner angle greater than 90° is formed, and insulation layers are strategically positioned to create an air gap with a low dielectric constant, reducing parasitic capacitance and electrical interference between neighboring cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If integration density is increased, then productivity is improved, but cell-to-cell interference increases causing memory cell errors
Solution Approach 1:
The device isolation region is segmented into multiple functional components: a trench structure for physical separation, an air gap for electrical isolation, and insulation layers for additional protection. This segmentation allows each component to address specific aspects of cell-to-cell interference while maintaining high integration density.
Solution Approach 2:
An air gap is introduced as an intermediary structure between adjacent memory cells. This air gap, having a low dielectric constant, acts as a mediator that reduces parasitic capacitance and electrical interference between cells while allowing the cells to remain in close proximity for high density.
2Reliability
If device isolation structure is added to suppress cell-to-cell interference, then reliability is improved, but device complexity increases
Solution Approach 1:
Multiple isolation functions are merged into a single integrated structure. The trench, air gap, and insulation layers work together as a unified device isolation region that provides both physical separation and electrical isolation, reducing the need for additional separate isolation structures.
Solution Approach 2:
The corner angle of the trench is optimized to greater than 90 degrees, and the air gap width is carefully controlled. These parameter optimizations enable effective isolation while simplifying the manufacturing process and reducing structural complexity compared to alternative designs.
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 air gap isolation structure effectively minimizes cell-to-cell interference, enhancing the reliability and integration density of non-volatile memory devices by reducing parasitic capacitance and ensuring accurate data storage.
Implementation Method 1
an air gap whose top is defined by a memory cell layer and whose bottom is defined by a layer other than that of the top
Data Source
AI summary
A non-volatile memory device includes a substrate having an active region defined by a device isolation region that has a trench and an air gap, a device isolation pattern positioned at a lower portion of the trench, a memory cell layer including a tunnel insulation layer, a trap insulation layer and a blocking insulation layer that are sequentially stacked on the active region and one of which extends from the active region toward the device isolation region encloses top of the air gap whose bottom is defined by a layer other than that of the top, and a control gate electrode positioned on the cell structure. The one of the insulation layer extending includes a recess at a region corresponding to the center of the air gap.