Air-Gap Wiring Structure for Low-Capacitance Reliable Interconnects
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Solution Overview
Problem
The miniaturization of semiconductor integrated circuit elements leads to narrower intervals between wiring lines, increasing capacity between wiring lines, which causes signal delay and reduces long-term reliability in semiconductor devices, and existing methods using air gaps in insulating films compromise structural stability.
Innovation Solution
A wiring structure with a specific cross-sectional shape of gaps between wiring lines, defined by curved and straight lines coupled at 90° or more, and an insulating film with a planar surface above these gaps, reduces parasitic capacity and stress concentration, enhancing structural stability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the interval between wiring lines is narrowed to increase integration density, then the capacity between wiring lines increases, but signal delay increases and long-term reliability deteriorates
Solution Approach 1:
The patent extracts the harmful dielectric material between adjacent wiring lines and replaces it with air gaps. By removing the solid insulating material from the gap regions between wiring lines, the parasitic capacitance is reduced without compromising the insulating function, as air serves as the dielectric medium with lower permittivity.
Solution Approach 2:
The patent introduces a porous insulating film structure containing air gaps within the insulating layer. This porous structure allows the insulating film to maintain its mechanical integrity and insulating properties while creating low-capacitance regions between adjacent wiring lines, effectively reducing parasitic capacitance.
2Reliability
If air gaps are formed between wiring lines to reduce capacity, then parasitic capacitance decreases, but structural stability deteriorates and cracks may form
Solution Approach 1:
The patent applies different structural qualities to different regions: the insulating film maintains a continuous solid structure in regions providing mechanical support, while air gaps are introduced only in the gap regions between adjacent wiring lines where electrical isolation is needed. This localized differentiation maintains structural stability while achieving capacitance reduction.
Solution Approach 2:
The patent creates a composite insulating film structure combining solid dielectric material and air gaps. This composite structure leverages the mechanical strength of the solid insulating material while utilizing the low permittivity of air to reduce parasitic capacitance, achieving both structural stability and electrical performance improvement.
3Reliability
If complex gap shapes are used to reduce capacity further, then parasitic capacitance decreases, but manufacturing precision requirements increase
Solution Approach 1:
The patent segments the insulating film into distinct regions: continuous solid insulating material providing mechanical support and discrete air gap regions for capacitance reduction. This segmentation is achieved through a two-step process involving formation of the insulating film followed by selective removal of material in gap regions, simplifying the manufacturing process compared to forming complex gap shapes directly.
Data Source
AI summary
Provided is a wiring structure having superior operation reliability. This wiring structure includes a plurality of wiring lines each extending in a first direction and disposed side by side in a second direction orthogonal to the first direction; and a first insulating film that covers the plurality of wiring lines and has a gap present in a gap region sandwiched between the plurality of wiring lines adjacent to each other in the second direction. Herein, the gap has a cross-sectional shape defined by an outline including only one curved line, or a cross-sectional shape defined by an outline that includes one or more curved lines and one or more straight lines coupled at two or more coupling sections and has an intersecting angle of 90° or more between the curved lines, between the straight lines, or between the curved line and the straight line at the coupling section.