Silicon-Rich STI Trench Structure for Deep Isolation
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Solution Overview
Problem
Conventional shallow trench isolation (STI) technologies face challenges in achieving effective isolation and expanding active region size due to limitations in trench depth and size, leading to poor performance in semiconductor structures.
Innovation Solution
A method involving the formation of a silicon-rich isolation layer within the trench, followed by an isolation oxide layer, which prevents substrate oxidation and allows for increased trench depth while maintaining active region size, using processes like chemical vapor deposition and in-situ steam generation to enhance isolation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the trench depth is increased to improve isolation effect, then the isolation performance is improved, but the active region size is reduced due to process limitations
Solution Approach 1:
The isolation layer is segmented into multiple layers: a silicon-rich isolation layer (first layer) and an oxide isolation layer (second layer). This segmentation allows the silicon-rich layer to be deposited to greater depths without causing substrate oxidation, while the oxide layer provides the actual isolation function. The segmentation resolves the contradiction by enabling deep trenches for isolation without sacrificing active region size.
Solution Approach 2:
The silicon-rich isolation layer acts as an intermediary between the substrate and the oxide isolation layer. It serves as a protective barrier that prevents oxidation of the substrate during the oxide layer formation process, while also providing structural support for the deeper trench configuration. This intermediary enables both deep trenches and preserved active region dimensions.
2Ease of manufacture
If conventional STI process is used to form isolation layer, then the process is simple, but the trench depth is limited and isolation effect is poor
Solution Approach 1:
The isolation layer is divided into two functional segments: a silicon-rich layer deposited by CVD and an oxide layer formed through oxidation. This segmentation maintains manufacturing simplicity by using standard semiconductor processes while achieving superior isolation effects through the combined functionality of both layers, particularly enabling deeper trench configurations.
Solution Approach 2:
The isolation structure uses composite materials consisting of silicon-rich material and oxide material in distinct layers. This composite approach combines the advantages of both materials: the silicon-rich layer provides deep trench filling capability and oxidation protection, while the oxide layer provides excellent electrical isolation properties, thereby improving isolation effect without significantly complicating the manufacturing process.
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 improves the isolation effect and performance of semiconductor structures by allowing deeper trenches and larger active regions without oxidizing the substrate, thereby addressing the limitations of conventional STI technologies.
Implementation Method 1
using processes like chemical vapor deposition and in-situ steam generation
Implementation Method 2
at least part of the first isolation oxide layer is formed by oxidizing a silicon-rich isolation layer
Implementation Method 3
using processes like chemical vapor deposition and in-situ steam generation to enhance isolation efficiency
Data Source
AI summary
A method for manufacturing a semiconductor structure includes: a substrate is provided, an isolation trench being formed on the substrate; a silicon-rich isolation layer is formed in the isolation trench, the silicon-rich isolation layer covering an inner surface of the isolation trench; and an isolation oxide layer is formed in the isolation trench. The isolation oxide layer fills up the isolation trench.