Floating Gate Air Gap Structure for Coupling and Leakage Isolation
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Solution Overview
Problem
As semiconductor structures are scaled down for increased density, coupling interference and leakage currents between adjacent floating gates in non-volatile memory devices become significant issues, affecting reliability and yield.
Innovation Solution
An air gap is formed between the third dielectric layer and the dielectric stack by sequentially depositing multiple dielectric layers and using a sacrificial layer, which is removed through wet etching to create the gap, thereby reducing interference and leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If semiconductor structures are scaled down to increase density, then integrated density is improved, but coupling interference and leakage current between adjacent floating gates increase
Solution Approach 1:
The patent introduces an air gap that segments the continuous dielectric structure between adjacent floating gates into separate regions. This segmentation physically isolates the electric fields of neighboring floating gates, preventing coupling interference while maintaining high density through compact cell design.
Solution Approach 2:
The air gap acts as an intermediary layer between adjacent floating gates and dielectric stacks. This intermediate air region mediates the electric field distribution, preventing direct coupling between adjacent structures while allowing each component to function independently.
2Reliability
If an air gap is introduced between dielectric layers, then coupling interference is reduced, but device complexity increases
Solution Approach 1:
The patent extracts a portion of the dielectric material to create an air gap region. By removing material rather than adding complex structures, the design achieves electrical isolation while maintaining relatively simple fabrication processes. The air gap is formed by selectively removing the sacrificial layer, leaving a void space that provides the necessary isolation.
Solution Approach 2:
The invention changes the physical parameter of the dielectric structure by introducing an air-filled region with different permittivity characteristics. This parameter change (from solid dielectric to air gap) fundamentally alters the electrical field distribution and reduces coupling interference without requiring complex additional components.
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 approach enhances the reliability and performance of the semiconductor structure by minimizing coupling interference and leakage currents, while maintaining the integrity of the dielectric stack and control gate layer.
Implementation Method 1
when a wet etching is performed to form the air gap
Data Source
AI summary
A semiconductor structure and a method of forming the semiconductor structure are provided. The method of forming the semiconductor structure includes forming a floating gate layer on a substrate. A trench is formed in the floating gate layer and the substrate. A first dielectric layer is formed in the trench. A second dielectric layer is formed on the first dielectric layer. A third dielectric layer is formed on the second dielectric layer. A first sacrificial layer is formed on the third dielectric layer. A dielectric stack is formed on the first sacrificial layer. A control gate layer is formed on the dielectric stack. The first sacrificial layer is removed to form an air gap between the third dielectric layer and the dielectric stack.