Semiconductor Isolation Structure With Air Gap for Lower Parasitic Capacitance
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Solution Overview
Problem
Existing isolation structures in semiconductor integrated circuits (ICs) are inadequate in reducing parasitic capacitance, which affects device performance and efficiency, particularly as ICs scale down to smaller technology nodes.
Innovation Solution
The formation of a Continuous Poly on Diffusion Edge (CPODE) structure with an air gap and low-k filler layer is introduced to reduce parasitic capacitance by forming a trench between neighboring active regions, using a high-k liner layer and low-k filler material, and subsequently creating an air gap to minimize electrical interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If existing isolation structures are used to divide active regions, then active region segmentation is achieved, but parasitic capacitance is not sufficiently reduced
Solution Approach 1:
The patent employs a low-k dielectric material with a porous structure to fill the isolation trench. This porous material reduces parasitic capacitance between active regions while maintaining effective electrical isolation, directly addressing the contradiction between reducing harmful capacitance and ensuring device performance reliability
Solution Approach 2:
The isolation structure uses a composite approach combining a high-k liner material (such as silicon nitride or silicon oxynitride) with a low-k dielectric material. The high-k liner provides excellent electrical isolation and mechanical strength, while the low-k filler reduces parasitic capacitance, together resolving the contradiction between isolation effectiveness and capacitance reduction
2Productivity
If geometry size is scaled down to increase functional density, then production efficiency increases and costs decrease, but parasitic capacitance reduction becomes more difficult
Solution Approach 1:
The patent changes the dielectric constant parameter of the isolation material by using low-k dielectric materials instead of traditional high-k materials. This parameter change enables effective parasitic capacitance reduction even as device dimensions scale down, allowing continued productivity improvement without being constrained by increasing capacitance issues
Solution Approach 2:
The patent applies different material properties to different regions of the isolation structure: a high-k liner material is applied to the trench walls and bottom for strong electrical isolation, while a low-k dielectric material fills the trench interior to minimize parasitic capacitance. This localized quality differentiation enables the structure to simultaneously support scaling for productivity while reducing harmful capacitance effects
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 effectively reduces parasitic capacitance, leading to improved device performance by minimizing RC delays and enhancing overall circuit efficiency.
Implementation Method 1
Existing isolation structures in semiconductor integrated circuits (ICs) are inadequate in reducing parasitic capacitance, which affects device performance and efficiency
Implementation Method 2
using a high-k liner layer and low-k filler material, and subsequently creating an air gap to minimize electrical interference
Data Source
AI summary
Semiconductor structures and methods are provided. An exemplary method according to the present disclosure includes receiving a fin-shaped structure comprising a first channel region and a second channel region, a first and a second dummy gate structures disposed over the first and the second channel regions, respectively. The method also includes removing a portion of the first dummy gate structure, a portion of the first channel region and a portion of the substrate under the first dummy gate structure to form a trench, forming a hybrid dielectric feature in the trench, removing a portion of the hybrid dielectric feature to form an air gap, sealing the air gap, and replacing the second dummy gate structure with a gate stack after sealing the air gap.