Semiconductor Interconnects with Air Gaps for RC Delay Reduction
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Solution Overview
Problem
As semiconductor devices evolve to smaller feature sizes, there is a need to reduce RC time delay and increase circuit speed, which existing technologies fail to achieve effectively due to limitations in dielectric materials and interconnect materials like aluminum.
Innovation Solution
The introduction of air gaps in a dielectric layer between metal patterns, formed by creating voids through a modifiable layer modification and removal process, reduces capacitance and dielectric constant, thereby decreasing RC delay and enhancing circuit speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional dielectric materials are used in interconnect structures, then manufacturing process is simple, but RC time delay is high and circuit speed is limited
Solution Approach 1:
The patent introduces air gaps (voids) within the dielectric layer to create a porous structure. This reduces the effective dielectric constant of the insulation material between conductive interconnect lines, thereby reducing capacitance and RC time delay, which directly improves circuit speed while minimizing time loss.
Solution Approach 2:
The patent creates a composite dielectric structure by combining solid dielectric material with air gaps (voids). This composite structure achieves a lower effective dielectric constant compared to traditional solid dielectric materials, reducing capacitance between interconnects and improving signal transmission speed.
2Productivity
If feature densities increase and conductive line widths are scaled smaller, then integration is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent changes the dielectric parameter (dielectric constant) by introducing air gaps, which allows for better electrical performance at higher feature densities. This parameter change enables continued scaling of conductive line widths while maintaining signal integrity and reducing interference, thus supporting higher productivity without proportionally increasing manufacturing precision requirements.
3Speed
If copper interconnects with low-k dielectric materials are used, then interconnect speed is increased, but device complexity increases
Solution Approach 1:
The patent uses air gaps (porous structure) within the dielectric layer to achieve lower effective dielectric constant. This approach reduces capacitance between copper interconnects, improving interconnect speed. The air gap formation through selective removal processes integrates with existing manufacturing workflows, managing device complexity while achieving speed improvement.
Data Source
AI summary
A semiconductor process includes the following steps. Metal patterns are formed on a first dielectric layer. A modifiable layer is formed to cover the metal patterns and the first dielectric layer. A modification process is performed to modify a part of the modifiable layer on top sides of the metal patterns, thereby top masks being formed. A removing process is performed to remove a part of the modifiable layer on sidewalls of the metal patterns but preserve the top masks. A dielectric layer having voids under the top masks and between the metal patterns is formed. Moreover, the present invention also provides a semiconductor structure formed by said semiconductor process.