Flash Memory Cell Structure With Low-K Spacer for Cross-Talk Reduction
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Solution Overview
Problem
As flash memory devices are miniaturized, the reduced gap between cells leads to increased parasitic capacitance and cross-talk effects, causing RC delays and performance degradation due to capacitance coupling between adjacent cells.
Innovation Solution
The implementation of a low dielectric constant (low-K) spacer sandwiched between the floating gate and the trench isolation structure, which reduces the parasitic capacitance by creating a gap with a dielectric constant lower than silicon oxide, either as a solid structure or an air spacer, thereby minimizing capacitance coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the device size is reduced to increase integration density, then the gap between cells is reduced, but parasitic capacitance between adjacent floating gates increases causing cross-talk
Solution Approach 1:
A low-K dielectric material is introduced as an intermediary substance between adjacent floating gates to reduce parasitic capacitance. The low-K spacer is formed on the sidewall of the floating gate and extends into the gap between cells, acting as a mediator that electrically isolates adjacent structures while maintaining physical proximity for high density
Solution Approach 2:
The dielectric constant parameter of the material between floating gates is changed from standard silicon oxide (K≈3.9) to low-K dielectric material (K<3.9). This parameter change directly reduces the capacitance value C=Kε0A/d, thereby reducing parasitic effects while maintaining the same geometric structure
2Area of stationary object
If the gap between cells is reduced to increase density, then more cells fit in the same area, but cross-talk effect between adjacent cells increases
Solution Approach 1:
The low-K spacer serves as an intermediary barrier between adjacent floating gates, reducing the electric field coupling that causes cross-talk. By placing this low-dielectric material in the gap region, adjacent cells can be positioned closer together while the spacer material suppresses capacitive coupling and prevents signal interference
Solution Approach 2:
The low-K dielectric material is applied locally only in the critical gap region between adjacent floating gates, rather than throughout the entire device. This localized application针对性地 addresses the cross-talk problem at the interface between cells while maintaining standard dielectric materials in other regions where high density is prioritized
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 solution effectively reduces parasitic capacitance and cross-talk effects, enhancing the operational performance of flash memory cells by minimizing the impact of adjacent cells on the target cell during voltage application.
Implementation Method 1
A low dielectric constant (low-K) spacer is disposed on a sidewall of the floating gate... a dielectric constant of the low-K spacer is smaller than a dielectric constant of the trench isolation structure
Data Source
AI summary
A structure of flash memory cell includes a substrate. A floating gate is disposed on the substrate. A low dielectric constant (low-K) spacer is disposed on a sidewall of the floating gate. A trench isolation structure has a base part disposed in the substrate and a protruding part above the substrate protruding from the base part. The low-K spacer is sandwiched between the floating gate and the protruding part of the trench isolation structure.