Buried Dielectric Air Gaps for Lower RC Semiconductor Interconnects
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Solution Overview
Problem
As semiconductor device density increases, parasitic capacitance effects become more pronounced, leading to decreased operation speed due to increased resistance-capacitance (RC) effects, and existing methods struggle to effectively reduce parasitic capacitance without altering the interconnect structure design.
Innovation Solution
Forming air gaps in the buried dielectric layer near the device structure, using a metal layer with openings surrounded by inter-layer dielectric (ILD) layers, which seals the air gaps to reduce parasitic capacitance, thereby improving operation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If device density increases, then device integration is improved, but parasitic capacitance increases and operation speed decreases
Solution Approach 1:
The patent introduces air gaps specifically in the buried dielectric layer beneath high-density device regions, creating localized low-dielectric constant zones where parasitic capacitance is most problematic. This targeted approach reduces capacitance in critical areas without requiring global structural changes to the entire device.
Solution Approach 2:
The air gap acts as an intermediary layer between the semiconductor device structure and the underlying substrate, mediating the electrical field interactions. By inserting this air layer with dielectric constant接近1, the patent reduces the capacitive coupling between adjacent devices, thereby reducing parasitic capacitance and RC effects while maintaining device density.
2Object-affected harmful factors
If air gap volume increases, then parasitic capacitance is reduced, but fabrication complexity increases
Solution Approach 1:
The air gaps are formed during the dielectric layer deposition process itself, rather than as a separate post-processing step. The deposition conditions are controlled to naturally create void spaces in the buried dielectric layer, integrating the air gap formation into the existing fabrication workflow and minimizing additional process complexity.
Solution Approach 2:
The patent controls the volume and distribution of air gaps by adjusting deposition parameters such as deposition rate, temperature, and material composition. By optimizing these parameters, the air gap volume is precisely controlled to achieve the desired parasitic capacitance reduction while maintaining manufacturability and avoiding excessive fabrication complexity.
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 formation of air gaps in the buried dielectric layer effectively reduces parasitic capacitance, enhancing the operational speed and performance of semiconductor devices by minimizing the dielectric constant and RC effects.
Implementation Method 1
The parasitic capacitance effect would be more obviously occurring. As usually known, the increase of the parasitic capacitance would cause the increase of resistance-capacitance (RC) effect
Implementation Method 2
the dielectric constant of air is rather approaching to 1, which is the material basically having the lowest dielectric constant
Data Source
AI summary
A semiconductor device is provided. The semiconductor device includes a device substrate, having a device structure layer and a buried dielectric layer, wherein the buried dielectric layer is disposed on a semiconductor layer of the device structure layer and the device substrate comprises a device structure. A metal layer is disposed on the buried dielectric layer and surrounded by a first inter-layer dielectric (ILD) layer. A region of the metal layer has a plurality of openings. The buried dielectric layer has an air gap under and exposing the region of the metal layer with the openings, wherein the air gap is located above the device structure in the device substrate. A second ILD layer is disposed on the metal layer and sealing the air gap at the openings of the metal layer.