Thermally Conductive Air Gaps for Low-Capacitance Interconnects
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Solution Overview
Problem
The integration of air gaps in semiconductor devices to reduce parasitic capacitance and enhance thermal conductivity is hindered by poor thermal conductivity and reliability issues such as via-to-line breakdown and time-dependent dielectric breakdown (TDDB).
Innovation Solution
A method for manufacturing semiconductor devices that involves forming air gaps by depositing a thermally conductive dielectric capping layer, a low-k dielectric coating layer, and a sustaining layer, followed by the removal of sacrificial features to create air gaps, which are then capped by the sustaining layer, thereby improving thermal conductivity and reducing capacitance while maintaining electromigration resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air gaps are integrated into semiconductor devices to reduce parasitic capacitance, then capacitance between metal features is reduced, but thermal conductivity deteriorates
Solution Approach 1:
The patent applies composite materials by combining air (low-k dielectric) with thermally conductive materials (such as diamond, cubic boron nitride, or aluminum nitride) to create a composite structure that simultaneously achieves low parasitic capacitance and high thermal conductivity. The air gap provides the dielectric isolation while the thermally conductive material fills the thermal management requirement.
Solution Approach 2:
The patent implements local quality by creating regions with different thermal conductivities within the dielectric structure. Specifically, thermally conductive regions are placed adjacent to heat-generating components (such as near via structures or active devices) while maintaining air gaps in other regions for capacitance reduction. This localized approach allows thermal management where needed while preserving the capacitance-reduction benefits elsewhere.
2Temperature
If air gaps are formed in semiconductor devices, then thermal conductivity is improved, but reliability issues such as via-to-line breakdown and TDDB worsen
Solution Approach 1:
The patent applies beforehand cushioning by introducing a sustaining layer that caps the air gaps before reliability issues can occur. This sustaining layer acts as a protective barrier that prevents via-to-line breakdown and time-dependent dielectric breakdown by providing mechanical support and electrical isolation, cushioning against potential failure modes before they manifest.
Solution Approach 2:
The patent uses an intermediary approach by introducing a sustaining layer as a mediator between the air gap structure and the surrounding dielectric environment. This sustaining layer serves as an intermediate structure that maintains the integrity of the air gap while providing the necessary mechanical and electrical properties to prevent reliability issues, acting as a buffer between the air gap and potential failure points.
3Reliability
If low-k dielectric materials are used to reduce parasitic capacitance, then capacitance between metal features is reduced, but processing problems increase
Solution Approach 1:
The patent applies the taking out principle by extracting the problematic low-k dielectric material and replacing it with a combination of air gaps and thermally conductive materials. Instead of using low-k materials that cause processing issues, the invention removes these materials from the structure and uses air (which has inherently low-k properties) combined with thermally conductive fillers, thereby eliminating the processing problems while maintaining the capacitance reduction benefit.
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 method effectively reduces capacitance and enhances thermal conductivity, while also improving electromigration resistance and preventing reliability issues like TDDB by using thermally conductive dielectric materials and a sustaining layer to cap the air gaps.
Implementation Method 1
a thermally conductive dielectric capping layer is conformally formed on the electrically conductive structure
Implementation Method 2
forming a sustaining layer over the dielectric coating layer to cover the sacrificial features... the sustaining layer to cap the air gaps
Implementation Method 3
conformally forming a dielectric coating layer on the thermally conductive dielectric capping layer... reducing capacitance
Data Source
AI summary
A method for manufacturing a semiconductor device includes preparing an electrically conductive structure including a plurality of electrically conductive features, conformally forming a thermally conductive dielectric capping layer on the electrically conductive structure, conformally forming a dielectric coating layer on the thermally conductive dielectric capping layer, filling a sacrificial material into recesses among the electrically conductive features, recessing the sacrificial material to form sacrificial features in the recesses, forming a sustaining layer over the dielectric coating layer to cover the sacrificial features, and removing the sacrificial features to form air gaps covered by the sustaining layer. The thermally conductive dielectric capping layer has a thermal conductivity higher than that of the dielectric coating layer.