Trench Isolation Nitridation for DRAM Retention Improvement
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Solution Overview
Problem
The challenge in semiconductor device manufacturing lies in reducing memory cell area as isolation structure spacing decreases, particularly in improving retention time in memory devices like DRAM, where existing methods struggle to effectively manage the nitridation process for enhanced performance.
Innovation Solution
The method involves forming a nitridation layer between the substrate and the isolation layer within trenches in the semiconductor device, using techniques like decoupled plasma nitridation or rapid thermal nitridation, to create a nitridation layer that improves the retention time of the semiconductor device, especially in memory devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If isolation structure spacing is reduced to decrease memory cell area, then device density is improved, but retention time deteriorates
Solution Approach 1:
The isolation structure is segmented into multiple functional layers: a first dielectric layer for electrical isolation, a second dielectric layer for mechanical support, and a nitridation layer for interface stabilization. This segmentation allows each layer to independently contribute to either area reduction or retention time improvement, resolving the contradiction between device density and retention performance
Solution Approach 2:
The isolation structure employs composite materials with different properties stacked together: low-k dielectric materials for reduced capacitance and improved density, high-k nitridation layers for enhanced interface stability and retention. This composite approach enables simultaneous achievement of smaller cell area and longer retention time by combining materials that individually address different aspects of the contradiction
2Ease of manufacture
If conventional isolation structures are used with reduced spacing, then manufacturing simplicity is maintained, but retention time performance deteriorates
Solution Approach 1:
The nitridation layer is formed preliminarily before the final dielectric layer deposition, and the isolation structure is configured in advance with specific layer thicknesses and material compositions optimized for retention. This preliminary action embeds retention-enhancing features into the fabrication process itself, allowing retention time improvement without adding significant manufacturing complexity
Solution Approach 2:
The invention changes key parameters of the isolation structure: dielectric constant values through material selection, layer thickness ratios, and nitrogen concentration in the nitridation layer. These parameter changes are integrated into existing manufacturing processes, enabling retention time enhancement while maintaining ease of manufacture through controlled variations in material properties rather than fundamental process changes
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 retention time of semiconductor devices by up to 36% or more by forming a nitridation layer that improves the structural integrity and performance of memory devices, addressing the limitations of existing isolation structures.
Implementation Method 1
using techniques like decoupled plasma nitridation or rapid thermal nitridation
Implementation Method 2
using techniques like decoupled plasma nitridation or rapid thermal nitridation
Data Source
AI summary
A method of manufacturing a semiconductor device is provided. The method includes providing a substrate. The method also includes forming a first trench within the substrate. The method further includes forming a first nitridation layer within the first trench. In addition, the method includes forming a first isolation layer on the first nitridation layer to form a first isolation structure.