Semiconductor Interconnect Air Gap Structure for RC Delay Reduction
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Solution Overview
Problem
The increasing integration of integrated circuits leads to smaller transistor dimensions and closer interconnect lead spacing, resulting in higher parasitic capacitance and RC delay in back-end interconnect structures, which existing technologies, such as the copper damascene process, struggle to mitigate effectively due to the challenges of using copper as an interconnect material.
Innovation Solution
A semiconductor structure formation method involving a base with a dielectric layer and pads, forming a dielectric structure that exposes pads and part of the dielectric layer, creating an insulating structure on the sidewall with an air gap between the dielectric and insulating structures, and a conductive structure covering the exposed pads and insulating structure, reducing parasitic capacitance by utilizing copper as an interconnect material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If interconnect leads are placed closer together to increase integration, then circuit density is improved, but parasitic capacitance increases
Solution Approach 1:
An air gap structure is introduced as an intermediary between adjacent conductive structures. This air gap acts as a mediator with low dielectric constant (close to 1), effectively reducing the parasitic capacitance between closely spaced interconnect leads while maintaining high circuit integration density.
Solution Approach 2:
The patent applies different dielectric properties to different regions: air gaps with dielectric constant close to 1 are placed in critical areas between conductive structures where capacitance reduction is most needed, while other regions use conventional dielectric materials. This localized quality differentiation optimizes the balance between integration density and parasitic capacitance.
2Reliability
If copper is used as interconnect material to reduce resistance, then electrical conductivity is improved, but manufacturing complexity increases
Solution Approach 1:
A barrier layer is formed on the substrate before depositing the copper layer. This preliminary action prevents copper diffusion into the dielectric layer, eliminating the need for complex post-deposition barrier structures and simplifying the overall manufacturing process while maintaining copper's excellent electrical conductivity.
Solution Approach 2:
The patent uses a composite structure consisting of a barrier layer (such as tantalum nitride or tungsten nitride) combined with copper. This composite material system provides both the low resistance benefits of copper and the diffusion barrier properties of the barrier layer, achieving reliable electrical conductivity without excessive manufacturing complexity.
3Loss of time
If air gaps are introduced to reduce parasitic capacitance, then RC delay is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The air gap structure is formed through self-aligned processes where the low dielectric constant material is deposited conformally on existing structures, and subsequent planarization automatically creates the air gaps. This self-service approach reduces the need for precise manual alignment and minimizes manufacturing precision requirements while effectively reducing RC delay.
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 method effectively reduces parasitic capacitance between interconnect leads by incorporating air gaps with low dielectric constants, thereby minimizing RC delay in semiconductor structures.
Implementation Method 1
The air gap reduces the parasitic capacitance between the conductive structures
Data Source
AI summary
A method of forming a semiconductor structure and a semiconductor structure are provided. The method of forming the semiconductor structure includes: providing a base, where the base includes a first dielectric layer and pads arranged at intervals in the first dielectric layer; forming a dielectric structure, where the dielectric structure exposes the pad and part of the first dielectric layer; forming an insulating structure, where the insulating structure is formed on a sidewall of the dielectric structure, the insulating structure covers a first partial sidewall of the dielectric structure, and an air gap is formed between a second partial sidewall of the dielectric structure and the insulating structure; and forming a conductive structure, where the conductive structure covers an exposed pad and an outer sidewall surface of the insulating structure.