Air-Gap Isolation Structure for Dielectric Breakdown Control
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Solution Overview
Problem
Semiconductor devices face dielectric breakdown issues due to high voltage differentials, leading to undesirable current flow and potential damage to dielectric layers, which existing capacitive Galvanic isolation structures fail to adequately address.
Innovation Solution
Incorporating air gaps in the dielectric layer between conductive structures, specifically at corners and edges of the conductive surfaces, to reduce electric field strength and prevent dielectric breakdown, along with additional dielectric material formation to further mitigate electric field concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive coupling is used for Galvanic isolation between voltage domains, then isolation is achieved, but dielectric breakdown can occur due to high voltage differentials
Solution Approach 1:
The patent applies local quality by creating air gaps specifically at the corners of the conductive structure where electric field concentration is highest. Instead of uniformly modifying the entire dielectric layer, the air gaps are strategically placed only at critical locations (corners) where the electric field strength is maximum, thereby locally reducing the harmful electric field concentration where it matters most while maintaining the overall capacitive coupling structure.
Solution Approach 2:
The air gaps act as an intermediary medium between the conductive structure and the semiconductor substrate. By introducing this intermediate air layer at the corners, the patent creates a transition zone that reduces the direct electric field interaction between high-voltage nodes, thereby mediating the electric field distribution and preventing dielectric breakdown in the main dielectric layer.
2Object-affected harmful factors
If air gaps are added to reduce electric field strength, then dielectric breakdown is prevented, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the dielectric layer into multiple regions: solid dielectric material in the bulk and air gap regions at the corners. This segmentation allows the structure to maintain simple, continuous dielectric coverage over most of the area while introducing discrete, localized air gaps only where needed, thereby reducing complexity compared to a fully modified dielectric structure.
Solution Approach 2:
The patent employs partial action by implementing air gaps only at the corners of the conductive structure rather than throughout the entire dielectric layer. This partial modification is sufficient to address the electric field concentration problem at critical locations without requiring comprehensive changes to the entire isolation structure, thereby minimizing the increase in device complexity.
3Manufacturing precision
If air gaps are formed at corners of conductive structures, then manufacturing precision is improved, but fabrication process complexity increases
Solution Approach 1:
The patent applies preliminary action by forming the air gaps at the corners during the dielectric layer formation process itself, before subsequent processing steps. The dielectric layer is deposited with pre-defined corner regions that will become air gaps, allowing precise placement to be established early in the fabrication sequence when alignment is most controllable, rather than attempting to add air gaps in later, more complex processing stages.
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 air gaps significantly reduce the likelihood of dielectric breakdown by lowering electric field strength, and the additional dielectric material enhances this effect, thereby protecting the semiconductor device from damage.
Implementation Method 1
The one or more air gaps are arranged to reduce the electric field strength between the corners of the lower surface of the conductive structure and the second conductive structure
Implementation Method 2
dielectric breakdown can occur between electrically conductive elements of two given voltage domains with a sufficiently high voltage differential
Implementation Method 3
Galvanic isolation can be achieved through capacitive coupling using isolation structures such as integrated capacitors
Data Source
AI summary
A semiconductor device may include a semiconductor substrate and an isolation structure including a first dielectric layer formed over the semiconductor substrate, the first dielectric layer including one or more air gaps, and a first conductive structure formed on the dielectric layer, the conductive structure having a lower surface that faces the semiconductor substrate. Respective air gaps of the one or more air gaps of the first dielectric layer each may be disposed directly between corners of the lower surface of the conductive structure and the semiconductor substrate.