Semiconductor Interconnect Air Gaps Mechanical Stress Protection
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Solution Overview
Problem
The mechanical vulnerability of semiconductor devices due to acicular air gaps between interconnects, which can lead to damage from shear stress and other mechanical forces during processes like chemical mechanical polishing, is not effectively addressed by existing interconnect structures.
Innovation Solution
A semiconductor device structure that includes a protective insulator with a higher Young's modulus than the surrounding dielectric, surrounding the interconnects and air gaps from the lateral sides, formed of materials like silicon nitride, to enhance mechanical strength and prevent damage from mechanical stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air gaps are formed between interconnects to prevent capacitance increase, then electrical performance is improved, but mechanical strength deteriorates
Solution Approach 1:
A protective insulator layer is introduced as an intermediary between the air gaps and the external environment. This protective insulator has higher mechanical strength than the surrounding dielectric and fills the air gaps, providing mechanical support while maintaining the electrical isolation function. The protective insulator absorbs mechanical stresses that would otherwise concentrate at the air gap interfaces and cause cracks.
Solution Approach 2:
The structure employs a composite material system consisting of the original dielectric material, air gaps, and the protective insulator material. The protective insulator is specifically selected to have higher Young's modulus than the surrounding dielectric, creating a composite structure that combines the electrical benefits of air gaps with the mechanical strength of the protective insulator material.
2Reliability
If conventional interconnect structure with air gaps is used, then electrical performance is improved, but damage from shear stress during CMP process occurs
Solution Approach 1:
The protective insulator acts as a cushioning layer that is already in place before the chemical mechanical polishing process. It absorbs and distributes the shear stresses generated during CMP, preventing these stresses from concentrating at the air gap interfaces and causing cracks. This beforehand cushioning protects the interconnect structure from mechanical damage during subsequent processing steps.
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 protective insulator effectively absorbs shear and perpendicular stresses, preventing cracks and damage to the interconnects and dielectric, thereby increasing the mechanical robustness of the semiconductor device.
Implementation Method 1
The protective insulator effectively absorbs shear and perpendicular stresses, preventing cracks and damage to the interconnects and dielectric
Data Source
AI summary
A semiconductor device includes a substrate, and interconnects provided above the substrate. The device further includes a first insulator that is provided on the interconnects and on air gaps provided between the interconnects, surrounds the interconnects from lateral sides of the interconnects, and is formed of a first insulating material. The device further includes a second insulator that surrounds an interconnect region including the interconnects and the air gaps from the lateral sides of the interconnects through the first insulator, includes no portion provided between the interconnects, and is formed of a second insulating material different from the first insulating material.