Air Gap Interconnect Structure for Low-k Dielectric RC Reduction
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Solution Overview
Problem
As semiconductor device sizes decrease, capacitive coupling between metal interconnect layers increases, limiting chip speed and proper operation, necessitating an improved method for forming an interconnect structure with reduced RC time constants.
Innovation Solution
The implementation of an air gap-containing interconnect structure with low-k dielectric layers and conductive features, where spacers with rectangular shapes create an air gap between conductive features, reducing the effective dielectric constant and enhancing RC performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If device size is decreased to increase integration density, then productivity is improved, but capacitive coupling between interconnect layers increases which worsens signal integrity and speed
Solution Approach 1:
The patent extracts the harmful dielectric material between adjacent interconnect lines and replaces it with air gaps. By removing the solid dielectric (k≈3.9) and substituting it with air (k≈1.0), the capacitive coupling between conductive features is significantly reduced, allowing higher integration density without sacrificing signal integrity
Solution Approach 2:
The patent introduces porous air gap structures between conductive features instead of using solid dielectric materials. These air gaps create a porous interconnect architecture that reduces the effective dielectric constant from approximately 3.9 to below 2.5, thereby reducing capacitive coupling while maintaining structural integrity
2Ease of manufacture
If conventional dielectric materials are used between interconnect layers, then ease of manufacture is maintained, but RC time constants increase which limits chip speed
Solution Approach 1:
The patent changes the dielectric parameter (effective dielectric constant) from conventional values (k≥3.9) to reduced values (k<2.5) by introducing air gaps. This parameter change reduces the RC time constants of the interconnect structure, enabling faster signal propagation and higher chip speed while remaining compatible with existing fabrication processes
Solution Approach 2:
The patent creates a composite interconnect structure combining solid dielectric regions with air gap regions. This composite architecture achieves an effective dielectric constant lower than either material alone would provide, optimizing both electrical performance for high speed operation and manufacturability through established deposition and etch processes
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 significantly reduces the effective dielectric constant, improving RC performance by lowering the resistance and capacitance between signal lines, thereby enhancing the speed and operation of semiconductor devices.
Implementation Method 1
reduces the effective dielectric constant and enhancing RC performance
Data Source
AI summary
An interconnect structure and a method of forming an interconnect structure are disclosed. The interconnect structure includes a low-k (LK) dielectric layer over a substrate; a first conductive feature and a second conductive feature in the LK dielectric layer; a first spacer along a first sidewall of the first conductive feature; a second spacer along a second sidewall of the second conductive feature, wherein the second sidewall of the second conductive feature faces the first sidewall of the first conductive feature; an air gap between the first spacer and the second spacer; and a third conductive feature over the first conductive feature, wherein the third conductive feature is connected to the first conductive feature.