Semiconductor Interconnect Air Gaps for Lower Parasitic Capacitance
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Solution Overview
Problem
Existing damascene processes face challenges in reducing parasitic capacitance in semiconductor interconnect structures as device scaling-down continues, particularly in achieving reduced parasitic capacitance at smaller sizes.
Innovation Solution
The method involves forming metal lines and vias in a semiconductor device using a masking structure with specific layering and etching processes, followed by recessing the structure to create openings filled with a sacrificial layer and capping liner, and then removing the sacrificial layer to form air gaps, which replace traditional low-k dielectric layers, thereby reducing dielectric constant and enhancing interconnect reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If low-k dielectric materials are used in traditional damascene processes, then parasitic capacitance is reduced, but the dielectric constant cannot be sufficiently lowered at smaller device sizes
Solution Approach 1:
The patent extracts the dielectric material from the air gap regions, removing it completely to create void spaces. This is achieved by forming sacrificial layers in desired air gap locations, building dielectric material over the structure, then selectively removing the sacrificial layers to leave empty spaces. The extracted dielectric material is replaced with air, achieving the lowest possible dielectric constant (approximately 1.0) and effectively eliminating parasitic capacitance between adjacent conductive interconnects.
Solution Approach 2:
The patent creates a porous interconnect structure by introducing air gaps between adjacent conductive interconnects. These air gaps form a porous architecture within the interlayer dielectric layer, where the pores are filled with air rather than solid dielectric material. This porous structure dramatically reduces the effective dielectric constant in the regions between conductors, thereby reducing parasitic capacitance while maintaining structural integrity through the surrounding dielectric material.
2Productivity
If device size is reduced to increase integration density, then production efficiency improves, but parasitic capacitance reduction becomes more difficult
Solution Approach 1:
The patent applies local quality by creating air gaps only in specific regions between adjacent conductive interconnects where parasitic capacitance needs to be reduced, rather than uniformly modifying the entire dielectric structure. The sacrificial layers are formed only in the spaces between conductors, and air gaps are created only where needed. This localized approach allows the interconnect structure to maintain high integration density with reduced parasitic capacitance in critical areas while preserving the integrity of the overall device architecture.
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 parasitic effects of line-to-line capacitance, improving device performance by replacing damaged low-k dielectric layers with air gaps that offer a lower dielectric constant, thus enhancing the reliability and performance of the interconnect structure.
Implementation Method 1
the sacrificial layer is removed to form air gaps
Data Source
AI summary
A method of forming a semiconductor device structure is provided. The method includes forming a masking structure with first openings over a semiconductor substrate and correspondingly forming metal layers in the first openings. The method also includes recessing the masking structure to form second openings between the metal layers and forming a sacrificial layer surrounded by a first liner in each of the second openings. In addition, after forming a second liner over the sacrificial layer in each of the second openings, the method includes removing the sacrificial layer in each of the second openings to form a plurality of air gaps therefrom.