Semiconductor Device With Isolation Structure
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Solution Overview
Problem
The scaling down of semiconductor devices increases complexity and results in higher parasitic capacitances due to isolation structures with high dielectric constants, which adversely impact device performance by increasing RC time delay and manufacturing costs.
Innovation Solution
The use of a bi-layer dielectric stack comprising a silicon nitride liner and a silicon oxide or silicon oxycarbide fill layer reduces the dielectric constant of isolation structures, thereby decreasing parasitic capacitance, and allows for independently controlled gate structures with varying dielectric constants in different device areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If isolation structures with high dielectric constants are used, then device isolation is achieved, but parasitic capacitance increases and device performance deteriorates
Solution Approach 1:
The isolation structure is segmented into a bi-layer dielectric stack comprising a first dielectric layer and a second dielectric layer with different dielectric constants. The first dielectric layer (with higher dielectric constant) provides strong isolation, while the second dielectric layer (with lower dielectric constant) reduces parasitic capacitance. This segmentation allows the structure to simultaneously achieve both isolation effectiveness and reduced parasitic effects.
Solution Approach 2:
Different regions of the isolation structure are assigned different dielectric materials with appropriate dielectric constants. The first dielectric layer uses material with higher dielectric constant for maximum isolation, while the second dielectric layer uses material with lower dielectric constant for reduced parasitic capacitance. This local quality differentiation optimizes both isolation performance and parasitic reduction in different spatial zones of the isolation structure.
2Productivity
If device dimensions are scaled down, then storage capacity and processing speed increase, but manufacturing complexity increases
Solution Approach 1:
The bi-layer dielectric stack structure serves multiple functions simultaneously: it provides electrical isolation between devices, reduces parasitic capacitance, and maintains compatibility with existing semiconductor manufacturing processes. By combining isolation and parasitic reduction functions in a single integrated structure, the solution avoids adding manufacturing complexity while delivering multiple performance benefits.
Solution Approach 2:
The invention changes the dielectric constant parameter by using a bi-layer structure with different dielectric constants in different layers. This parameter differentiation allows optimization of both isolation effectiveness and parasitic capacitance without requiring fundamental changes to the manufacturing process, thus improving productivity while maintaining manageable complexity.
3Reliability
If isolation structures with high dielectric constants are used, then electrical isolation is improved, but RC time delay increases and device performance decreases
Solution Approach 1:
The isolation structure is divided into two layers with different dielectric constants. The first layer provides strong electrical isolation with its higher dielectric constant, while the second layer reduces the overall capacitance component of the RC time delay with its lower dielectric constant. This segmentation enables simultaneous optimization of isolation and speed performance.
Solution Approach 2:
The bi-layer structure applies different dielectric qualities to different spatial zones: the first dielectric layer (higher constant) addresses the isolation requirement, while the second dielectric layer (lower constant) addresses the parasitic capacitance and RC time delay requirement. This local quality assignment resolves the contradiction between isolation and speed.
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 reduces parasitic capacitance by 30% to 50% and minimizes performance and cost variability across semiconductor devices, enhancing device performance and manufacturing efficiency.
Implementation Method 1
The use of a bi-layer dielectric stack comprising a silicon nitride liner and a silicon oxide or silicon oxycarbide fill layer reduces the dielectric constant of isolation structures, thereby decreasing parasitic capacitance
Data Source
AI summary
A semiconductor device with isolation structures of different dielectric constants and a method of fabricating the same are disclosed. The semiconductor device includes fin structures with first and second fin portions disposed on first and second device areas on a substrate and first and second pair of gate structures disposed on the first and second fin portions. The second pair of gate structures is electrically isolated from the first pair of gate structures. The semiconductor device further includes a first isolation structure interposed between the first pair of gate structures and a second isolation structure interposed between the second pair of gate structures. The first isolation structure includes a first nitride liner and a first oxide fill layer. The second isolation structure includes a second nitride liner and a second oxide fill layer. The second nitride layer is thicker than the first nitride layer.