Dielectric Capping Structure for Low-Capacitance Interconnects
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Solution Overview
Problem
As semiconductor integrated circuits are scaled down, the increased density and reduced spacing between conductive features lead to higher parasitic capacitance, increasing power consumption and time delay, which existing low-k dielectrics struggle to effectively mitigate due to damage from etching processes.
Innovation Solution
The implementation of a dielectric capping layer and self-assembled monolayer (SAM) to prevent damage from etchants during the formation of air-gaps between conductive wires, reducing capacitance and preventing metal ion diffusion, thereby enhancing the reliability and performance of the interconnect structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If low-k dielectrics are used to reduce parasitic capacitance, then power consumption and time delay are reduced, but the dielectric material suffers damage from etching processes
Solution Approach 1:
A capping layer is introduced as an intermediary protective structure between the etchant and the low-k dielectric material. The capping layer serves as a mediator that allows the etching process to proceed while protecting the underlying dielectric from damage, thus enabling capacitance reduction without compromising structural integrity
Solution Approach 2:
The capping layer is applied preliminarily before the etching process to prevent damage in advance. By preparing this protective barrier beforehand, the low-k dielectric is shielded from etchant exposure, allowing the etching to create air-gaps for capacitance reduction while maintaining dielectric integrity
2Productivity
If spacing between conductive features is reduced to increase density, then device integration is improved, but parasitic capacitance increases
Solution Approach 1:
Air-gaps with extremely low dielectric constant are created locally between adjacent conductive features while maintaining close spacing. This local modification of dielectric quality allows high device density to be achieved without the penalty of increased parasitic capacitance, as the low-k regions are precisely positioned where needed
Solution Approach 2:
The interconnect structure uses a composite approach combining conventional dielectric materials with air-gap regions. The air-gaps act as extreme low-k material inserts within the dielectric matrix, creating a composite structure that reduces parasitic capacitance while allowing close spacing of conductive features for high density
3Loss of energy
If air-gaps are created between conductive wires to reduce capacitance, then power consumption is reduced, but the conductive capping layer suffers etch damage
Solution Approach 1:
The dielectric capping layer serves as a protective intermediary that shields the conductive capping layer from etchant exposure during air-gap formation. This intermediary structure enables the etching process to create capacitance-reducing air-gaps while preventing damage to the underlying conductive layer
Solution Approach 2:
The dielectric capping layer is applied preliminarily over the conductive capping layer before the etching process. This preliminary protective coating allows subsequent etching to proceed without damaging the conductive material, enabling precise air-gap creation while maintaining manufacturing precision
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
This approach effectively reduces capacitance and RC delay while preventing damage to conductive capping layers and wires, improving the performance and reliability of the interconnect structure by maintaining the structural integrity and reducing etch damage.
Implementation Method 1
a self-assembled monolayer (SAM) is selectively deposited over an upper surface of the first inter-level dielectric (ILD) structure such that the SAM is laterally offset from a top surface of each conductive capping layer
Implementation Method 2
A dielectric capping layer is selectively deposited along a top surface of each conductive capping layer
Implementation Method 3
The dielectric capping layer is configured to prevent damage to the conductive capping layer and/or the plurality of conductive wires by a chlorine-based etchant
Implementation Method 4
air-gaps disposed laterally between adjacent conductive wires within the plurality of conductive wires... reduce parasitic capacitance and correspondingly improve device performance
Data Source
AI summary
Some embodiments relate to a semiconductor structure including a conductive wire disposed within a first dielectric structure. An etch stop layer overlies the first dielectric structure. A dielectric capping layer is disposed between an upper surface of the conductive wire and the etch stop layer. An upper dielectric layer is disposed along sidewalls of the conductive wire and an upper surface of the etch stop layer. The upper dielectric layer contacts an upper surface of the dielectric capping layer and has a top surface vertically above the etch stop layer.