Inter-Wire Cavities in Integrated Chips to Cut RC Delay
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Solution Overview
Problem
Integrated chips face performance limitations due to capacitance between metal wires, which contributes to resistive-capacitive (RC) delay, primarily caused by the high dielectric constant of the material separating them, leading to low performance and reliability.
Innovation Solution
Incorporating cavities with a low dielectric constant gas, such as air, between metal wires, defined by dielectric caps and etch-stop layers, to reduce capacitance and prevent damage to the wires during formation, maintaining structural integrity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal wires are separated by a dielectric layer with high dielectric constant, then structural integrity is maintained, but capacitance between wires increases leading to RC delay
Solution Approach 1:
The patent changes the dielectric parameter by introducing cavities filled with low dielectric constant material (air or gas) between metal wires. This reduces the effective dielectric constant in the inter-wire region, thereby reducing capacitance and RC delay while maintaining structural integrity through the surrounding dielectric material and etch-stop layers.
Solution Approach 2:
The patent introduces a porous or cavity-containing structure between metal wires, where the cavities are filled with low dielectric constant material. This porous-like structure reduces the effective dielectric constant compared to a solid dielectric layer, achieving lower capacitance while maintaining mechanical support through the surrounding structures.
2Loss of time
If cavities are formed between metal wires to reduce capacitance, then RC delay is reduced, but damage to metal wires may occur during formation
Solution Approach 1:
The patent applies preliminary protective actions by forming etch-stop layers and dielectric caps before cavity formation. These protective structures are prepared in advance to prevent damage to metal wires during the subsequent cavity formation process, ensuring wire integrity while enabling capacitance reduction.
Solution Approach 2:
The patent implements beforehand cushioning by introducing etch-stop layers and dielectric caps that act as protective barriers during cavity formation. These structures cushion or protect the metal wires from potential damage during the etching or formation processes, ensuring wire integrity is maintained while cavities are created to reduce capacitance.
3Loss of time
If cavities with low dielectric constant gas are introduced, then capacitance is reduced, but device complexity increases
Solution Approach 1:
The patent extracts or removes portions of the dielectric material between metal wires to create cavities. This extraction approach simplifies the overall structure compared to using complex low dielectric constant materials, as it involves removing material rather than adding complex structures, while still achieving capacitance reduction through the air or gas-filled cavities.
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 solution effectively reduces RC delay and improves chip performance by lowering capacitance between metal wires while ensuring the integrity and reliability of the metal wires by using a low dielectric constant gas in the cavities.
Implementation Method 1
Incorporating cavities with a low dielectric constant gas, such as air, between metal wires, defined by dielectric caps and etch-stop layers, to reduce capacitance
Data Source
AI summary
The present disclosure relates to an integrated chip comprising a substrate. A first conductive wire is over the substrate. A second conductive wire is over the substrate and is adjacent to the first conductive wire. A first dielectric cap is laterally between the first conductive wire and the second conductive wire. The first dielectric cap laterally separates the first conductive wire from the second conductive wire. The first dielectric cap includes a first dielectric material. A first cavity is directly below the first dielectric cap and is laterally between the first conductive wire and the second conductive wire. The first cavity is defined by one or more surfaces of the first dielectric cap.