Tapered STI With Void For Semiconductor Isolation
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Solution Overview
Problem
The miniaturization of semiconductor devices leads to increased complexity in manufacturing, resulting in challenges such as poor electrical isolation, crack development, and high yield loss due to the difficulty in forming effective isolation structures and managing thermal stress between different materials with varying coefficients of thermal expansion.
Innovation Solution
A semiconductor structure featuring a shallow trench isolation (STI) with a tapered first portion and a second portion extended into the substrate, including a void enclosed by the STI, which reduces parasitic capacitance and thermal stress by forming an air gap with a low dielectric constant, allowing for improved electrical isolation and reduced sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If isolation structures are formed to electrically isolate components, then electrical isolation is improved, but manufacturing complexity increases and may cause poor electrical isolation, cracks or high yield loss
Solution Approach 1:
The isolation structure is divided into multiple portions (first portion, second portion, third portion) with different configurations. The first portion has a first configuration, the second portion has a second configuration, and the third portion has a third configuration, allowing each segment to address specific manufacturing challenges while maintaining overall electrical isolation functionality
Solution Approach 2:
Different portions of the isolation structure are assigned different local properties and configurations tailored to specific regions. The first portion extends to the surface in a first direction, the second portion extends in a second direction, and the third portion has a third configuration, optimizing electrical isolation and stress management locally throughout the structure
2Productivity
If component density is increased to achieve miniaturization, then device functionality is improved, but distance between components decreases making isolation structure formation challenging
Solution Approach 1:
The isolation structure utilizes multiple spatial dimensions and directions to achieve effective isolation. By extending portions in different directions (first direction, second direction, third direction) and creating a multi-level configuration, the structure achieves comprehensive isolation even when component spacing is reduced due to miniaturization
3Adaptability or versatility
If different materials with different coefficients of thermal expansion are used, then device functionality is improved, but thermal stress increases leading to crack development
Solution Approach 1:
Different portions of the isolation structure are designed with different configurations to locally manage thermal stress. The first portion, second portion, and third portion have distinct geometries and orientations that distribute and mitigate thermal stress caused by coefficient of thermal expansion mismatches between different materials in the device
Solution Approach 2:
The isolation structure is segmented into multiple portions that can independently manage thermal stress in different regions. This segmentation allows each portion to be optimized for local thermal conditions, preventing stress concentration that would lead to crack development
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 structural configuration of the STI with a void allows for controlled air gap formation, minimizing parasitic capacitance and thermal stress, thereby enhancing electrical isolation and reducing defects in semiconductor devices.
Implementation Method 1
a void enclosed by the STI, which reduces parasitic capacitance and thermal stress by forming an air gap with a low dielectric constant
Implementation Method 2
reduces parasitic capacitance and thermal stress by forming an air gap with a low dielectric constant
Implementation Method 3
managing thermal stress between different materials with varying coefficients of thermal expansion
Data Source
AI summary
A semiconductor structure includes a semiconductive substrate including a first surface and a second surface opposite to the first surface, a shallow trench isolation (STI) including a first portion at least partially disposed within the semiconductive substrate and tapered from the first surface towards the second surface, and a second portion disposed inside the semiconductive substrate, coupled with the first portion and extended from the first portion towards the second surface, and a void enclosed by the STI, wherein the void is at least partially disposed within the second portion of the STI.