Air Gap Formation in 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 form air gaps in dielectric layers to mitigate this issue.
Innovation Solution
The formation of air gaps in the buried dielectric layer near device structures within the semiconductor device, achieved by creating openings in a metal layer surrounded by inter-layer dielectric (ILD) layers, which reduces parasitic capacitance by sealing the air gaps with subsequent dielectric layers.
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 regions where parasitic capacitance is most problematic (near device structures and interconnect structures), rather than uniformly across the entire device. This localized approach reduces parasitic capacitance in critical areas while maintaining device density and integration.
Solution Approach 2:
The patent uses air gaps as intermediary structures between conductive elements (device structures, interconnect structures, and metal layers). These air gaps act as mediators that reduce capacitive coupling between adjacent conductors, thereby reducing parasitic capacitance and improving operation speed.
2Object-affected harmful factors
If air gap volume increases, then parasitic capacitance is reduced, but fabrication complexity increases
Solution Approach 1:
The patent forms air gaps during the fabrication process by selectively removing dielectric material before final interconnect structure formation. This preliminary creation of air gaps integrates smoothly into the existing fabrication flow, avoiding the need for complex post-fabrication modifications while achieving the desired parasitic capacitance reduction.
Solution Approach 2:
The patent controls the volume and dimensions of air gaps by adjusting fabrication parameters such as etch depth, pattern size, and dielectric layer thickness. By optimizing these parameters, the patent achieves effective parasitic capacitance reduction with manageable air gap volumes that do not excessively complicate the fabrication process.
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, thereby enhancing the operation performance of semiconductor devices by minimizing the RC effect and improving speed.
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
A second ILD layer is disposed on the metal layer and sealing the air gap at the openings of the metal layer
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. 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. A second ILD layer is disposed on the metal layer and sealing the air gap at the openings of the metal layer.